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Home > Home Wiring USA Archive: NEC 1999 > Accessory Structures to Dwellings > Wiring a Detached Garage (NEC 1999)

Wiring a Detached Garage (NEC 1999)

By Warren Goodrich
Wiring a Detached Garage (NEC 1999)

EXAMPLE OF WIRING A RESIDENTIAL DETACHED BUILDING DESIGNED AS A STORAGE AND / OR GARAGE.

No minimum electrical wiring is required in a detached garage at all, if you do not install electricity to that structure.

You have several options in the designs to supply power to the detached structure from your dwelling.

You should also refer to a link in this “Home Wiring” site called “WIRING A SERVICE” for details involving services and common services serving two or more buildings or structures. There is a detailed section included at that link providing the explanations that you may desire related to the service in the dwelling or in the detached structure or both.

If you are attempting to wire a garage that is detached as an accessory building to a dwelling, then the absolute minimum wiring that would meet the minimum safety standards set forth in the NEC would be suggested as follows:

MINIMUM WIRING REQUIRED IF ELECTRICITY SERVES THAT DETACHED STRUCTURE;

The minimum wiring required in a detached garage, that has electricity installed to the structure, would include switches at the service [human] door to control a light inside the structure, Article 210-70-A-2 and a light serving the stoop outside the garage service door. Vehicular doors of a garage are exempt from any lighting requirements. A minimum of one GFCI protected receptacle somewhere inside the attached garage is also required. Article 210-52 Article 210-8-A-2 The light that is installed to serve the inside of the garage, and controlled at the service door may be wired as a three way switch { two switches controlling the same lighting } to serve as any second switch located at a second service door controlling the same light. You may decide on an option to install two lights inside the garage, one inside light controlled at the service door and the second inside light controlled at the garage’s second service door. The first option { using a three way switch serving the same light } is the most common choice to reduce confusion in switching systems and a possible reduction in wiring cost. Any second switch at any second service door is only voluntary and not required to meet minimum safety standards. There is an exception available considering the stoop light. If you have a dusk to dawn light that is always on automatic such as a photo cell, then that dusk to dawn light may serve as that garage stoop light if that dusk to dawn light is left in automatic control and if that dusk to dawn light also lights that stoop area outside the garage service door. Article 210-70-A-2-Exception

If you desire to provide more wiring you might want to check the following electrical requirements, if present, in an attached garage:

All readily accessible receptacles in an attached garage must be GFCI protected.

Article 210-8-A-1

The following exceptions can apply, if they meet the requirements of the exceptions. If a duplex receptacle is located behind a large appliance such as a combination of any two, refrigerator, freezer, washer, gas dryer etc., making the duplex receptacle “not to be readily accessible” and if this duplex receptacle is located behind the large appliance, then the GFCI protection is not required to protect that duplex receptacle serving those two appliances. Article 210-8-A-2-Exc. 2 If a single receptacle is located behind a single appliance, and made not readily accessible, then a GFCI protection is also not required. Article 210-8-A-2-Exc. 2 If a receptacle serving that large appliance is located so that it is “readily accessible” then that receptacle must be a single receptacle, and not a duplex receptacle, and again is not required to be protected by a GFCI. Article 210-8-A-Exc. 2

If you have a washer and a gas dryer, and the receptacle is designed so that both appliances are going to be left plugged into the same duplex receptacle on a permanent basis, and this receptacle is located behind either the washer or dryer, then the GFCI protection is not required, in this particular scenario. If you have receptacles out of reach {not readily accessible} such as located on the wall or ceiling and located above approximately 8’, then the GFCI protection is not required. These receptacles would not be considered as readily accessible. If you use normal lighting fixtures that are constructed without a receptacle mounted on the fixture, then GFCI protection is not required. A light fixture with a receptacle mounted on the fixture must be GFCI protected, if readily accessible as described above. Article 210-8-A-2 Any receptacle dedicated as large appliance equipment, and that is not GFCI protected will not fulfill the one receptacle requirement serving that detached garage if power is installed in that detached garaged. Article 210-8-A-2

HAZARDOUS LOCATIONS INVOLVING GARAGES;

There is a statement in the NEC that says you must not have electrical wiring, or an open flame appliances within 18” of the floor because that area is considered as a Class 1 hazardous location. Article 511-3-A This NEC requirement applies only to commercial garages, not residential garages. Residential garages are exempt from this requirement. Code Mute Be careful of this rule. A detached garage may be declared by the “authority having jurisdiction” to be a commercial garage even if located in your back yard. Article 90-4 This ruling as to whether a detached garage is a commercial or a residential garage would depend on the design, size of the structure, or the apparent use of the structure, or even the master plan assigning the zoning classifications of your property.

SPECIAL CIRCUITS AND CONSIDERATIONS IN DESIGN;

Outside receptacles, basement receptacles, and garage receptacles can be run on the same circuits if found in the same structure, and those devices can be protected by the same GFCI device. If a kitchen or a bathroom is installed in this detached garage, then these receptacles in that kitchen or bathroom must be dedicated as their own circuits. Kitchen and bathroom receptacles must not be wired on the same circuits as the garage, basement or outside receptacle circuits, not even a combination including both the kitchen and bathroom are allowed. Kitchen and bathrooms must have their own 20 amp receptacle circuits. Article 210-52-B-2 and Article 210-11-C You should refer to wiring a kitchen or wiring a bathroom, in the heading of wiring a dwelling, if you have a kitchen or bath in this detached garage.

TYPE OF GFCI PROTECTIVE DEVICES TO CHOOSE FROM;

There are two forms of GFCI protective devices. You may use a receptacle style GFCI protective device, or a breaker style GFCI protective device. Both devices are designed to be installed at the beginning of the circuit to be protected, only. Do not install GFCI receptacles for more than the first receptacle on that certain circuit, just install one GFCI receptacle as the first receptacle on that circuit and then install a normal receptacle on all the rest of that circuit.

A breaker style GFCI protective device is designed to be both the overcurrent device [breaker or fuse], and the GFCI protective device incorporated as one unit, and installed in the distribution panel.

The receptacle style GFCI protective device is designed to serve as both the first duplex receptacle, and the GFCI protective device, incorporated as one unit and installed as the first receptacle on the circuit. The receptacle style GFCI protective device is designed to protect itself as a receptacle, and it is designed to also protect all receptacles located the loads side of that GFCI device installed on that same circuit coming from that same GFCI protective device located as the first receptacle on the circuit.

You might want to compare the cost factor between a breaker style GFCI protective device, and the receptacle style GFCI protective device. When you compare the difference in cost remember to price the normal breaker, and the receptacle style GFCI device compared to the breaker style GFCI protective device, and a normal receptacle as required in each wiring design you may choose. I suspect you will find the GFCI receptacle, and normal breaker to be much cheaper than the GFCI breaker. Both devices will do the job, and should meet the NEC minimum requirements. Its your choice.

SPECIAL RECEPTACLE CONFIGURATION DESIGNS EXEMPT FROM GFCI PROTECTION REQUIREMENTS;

If you are using a circuit that is rated 220 volts, or over 30 amp rated, or a circuit that is hard wired without a receptacle, then no GFCI protection is required.

NUMBER OF RECEPTACLES ALLOWED ON A BRANCH CIRCUIT;

Calculating the maximum number or receptacles allowed on a circuit in a garage

If you have a question as to how many receptacles are allowed on a circuit, then you may wire your dwelling’s garage by designing your general use receptacles in that garage with no more that 10 receptacles on a 20 amp circuit or no more than 8 receptacles on a 15 amp circuit. This is allowed in Article 220-13 for commercial style building or as a non dwelling design of receptacle circuits.

Actually if allowed by your Electrical Inspector you could discard the 80% rule required for continuous use on these circuits because they are really general use convenience receptacles located in a dwelling setting that should normally be considered as non- continuous use and should be allowed to be calculated at 100% of the circuits ampacity. If you discarded the 20% reduction as described for continuous use and design your receptacle circuits as residential use at 100%, then you could put 13 receptacles on a 20 amp circuit and 10 receptacles on a 15 amp circuit and still use the 180 volt amp rule calculated at 100% for residential use, instead of the 80% for continuous use design. Just consider what you plan to do in that garage and don’t install more than the 13 receptacles on a 20 amp circuit or 10 on a 15 amp circuit if you are allowed to calculate your general use receptacles in your garage at 100%. If your inspector requires the 20% reduction considering your general use receptacles, then you may install 10 on a 20 amp circuit or 8 on a 15 amp circuit using an 80% load calculation per circuit. Article 210-19

SPECIAL DESIGN REQUIREMENTS INVOLVING MOTORS;

Dedicated branch circuit design for motors only.

If you are utilizing motors, or other such equipment, then you would have to calculate the load on that circuit created by all motors {full load current rating}, plus any other equipment on that circuit called other loads, then add 25% of the full load current of the largest motor on that circuit, then divide that answer into either the 1,920 Va. for 12 ga., or 1,440 Va for 14 ga. for continuous use at 80%

Branch circuit conductors serving a single motor would be sized by Article 430-22 taking the full load current of that motor, and increasing that full load current rating times 125%. That answer will tell you the required ampacity of that dedicated motor branch circuit conductor then refer to Table 310-16, using the 60 degree column if smaller than a 1 awg conductor or the 75 degree column if larger than a 1 awg conductor and only if that conductor is rated at least in temperature rating of that column, to obtain the minimum size of the conductor required. Article 110-14-C Remember the ampacity of a circuit is rated by the smallest ampacity associated to that conductor. Also remember that Article 240-3-D is not exempt from consideration of its ampacity limitations of 14 amps on 14 awg, or 20 amps on 12 awg or 30 amps on 10 awg because if other loads are added to this motor circuit the exemption found in Article 240-3-D would not be allowed to be used. This exemption is for motors, only .

If you have more than one motor, or motors and other loads on that feeder circuit, then just take the largest motor’s full load current, and add 25% to that motors full load current, then add the connected load of utilization equipment, or full load current of each additional motor added onto that feeder circuit. The total amps you come up with would be the ampacity requirement of the conductor serving as that feeder circuit. Article 430-24 Also remember that using 15 or 20 amp circuits, when installing motors or motors and other loads or more than one motor on a branch circuit, no one motor may be sized in amps more than 50% of the total ampacity of that branch circuit. Article 210-23-A Remember, also, that for dwelling premises you are not allowed to install lighting on any circuit larger than 15 or 20 amp circuits. Article 210-23-B & C For single circuit motors only on a certain circuit, also remember that Article 240-3-D is exempt from consideration of its ampacity limitations of 14 amps on 14 awg, or 20 amps on 12 awg or 30 amps on 10 awg because motors are the when otherwise specifically mentioned in the Code. When dealing with motors you may use the actual ampacity rating found in Table 310-16 which is a bit higher in ampacity ratings for these smaller conductors. Remember these higher ampacity ratings found in Table 310-16 concerning these conductors are only valid if these conductors are used as a branch circuit conductor carrying a single motor that has an overload built into that motor, or is with a separate overload protection device designed for motors. Most single phase motors contain a built in overload protective device as required in Articles 430-32 and 430-34. Check the name plate of the motor, and you should find a block on that name plate that says thermal protection with a “T” in that block on the name plate, or check to see if that motor has a red reset button on that motor. If so, then you have a thermally protected motor. For circuits with more than one motor or motors, and other loads on the same circuit, 14 Ga. is good for 15 amps and 12 Ga. is good for 20 amps and 10 Ga. is good for 30 amps and 8 Ga. is good for 40 amps. Article 240-3-D

A single motor load using the larger ampacity of conductors 14 Ga.,12 Ga, or 10 Ga found in Table 310-16., would be air compressors, drill presses, small wood planers, table saws, etc.

An arc welder would usually be rated at 60 amp, and does not have any 120 volt loads on that arc welder unit. Therefore a 6 Ga. Romex with an equipment grounding conductor containing a black, white and bare conductor in that cable would fulfill the needs for that welder. No neutral would be used. Most wire style welders are much smaller in amp loads. Check you wire style welder such as a mig or tig for the amp rating on its name plate, and whether it has any 120 volt loads on that machine requiring a neutral conductor in its feeder. You can now find available a wire welder that is 240 volt rated with no 120 volt equipment in that machine that also requires only a 20 amp 240 volt circuit. A 20 amp breaker with 12/2wGrnd Romex installed as the garage wiring may be all that is needed for this type of wire welder. Just check your name plate, checking amp rating, and if 120 volt equipment is in that machine to decide what branch circuit size, and conductor is required.

A thought for future, if you build a detached garage try to keep in mind that you would often find yourself working just outside the overhead door in the driveway with you welder, or even hand tools requiring 120 volts. You might want to install your welder plug, and or a 120 volt GFCI protected convenience receptacle at your overhead door for this work practice, that you might be doing outside your garage.

Another thought, if you have a welder, that you may weld both inside and outside, and if your garage is large enough to make distance a consideration limiting your welder cord length, then a trick of the trade may be used. An article in the code allows you to install two welder plugs in opposite ends of your garage, and install both welder plugs on the same 60 amp circuit for an arc style welder, or even a 240 volt wire welder that is 20 amp rated. The reason you can do this is that you most likely would only have one welder, and one person welding. This should be considered as a non-coincidental load as referred in Article 220-21 allowing both welder plugs on the same circuit without consideration of making those two welder plug locations bigger but just considering them as one welder load as an either or scenario. Just an extra thought for you to ponder.

FORM OF DISCONNECT REQUIRED FOR MOTORIZED EQUIPMENT;

Please keep in mind that the Code requires a form of disconnect on all equipment. Article 422-30 There is an exception allowing the breaker of a panel to serve as a disconnect if that breaker is within sight. Article 422-31-B If you were to research, you should find the definition of “in sight” is only if you can see the breaker at that motor, and only if that motor is within 50’ of the breaker. Both requirements must be met to be considered as “within sight”. Article 100

A receptacle may serve as a form of disconnect, {if it is not a convenience style duplex receptacle, example would be a twist lock receptacle or a 220 volt style receptacle or a single receptacle located behind the equipment making that receptacle not readily accessible}.

A non-fused disconnect may serve as a disconnect Article 422-30, if the circuit is protected at the beginning of the circuit by an overcurrent device such as a fuse or breaker at the beginning of that branch circuit, and if that motor is with an overload such as a thermal device in the motor, or a red reset button on the motor. Article 240-21 A second fuse or breaker is not required on a circuit to serve as a form of disconnect, only a form of disconnect is required. Article 422-30

WIRING STYLE AND TYPE OF CONDUCTORS ALLOWED;

Non-metallic sheathed cable [Romex] is an accepted wiring practice, if not subject to physical damage in garages. Article 336-4 Most inspectors will consider type NMB cable [Romex] as not subject to physical damage, if ran within a wall space, whether dry walled or not. Most inspectors will react to a type NMB cable that is ran on the front edge surface of the studs or posts. The inspector will most likely consider this wiring method to be exposed to physical damage. Article 336-6-B You might lean a ladder, or similar item against that stud or post, and be laying against the cable. This, commonly, would be considered to be exposed to physical damage. Any wiring exposed to the outside elements, weather or sun, would be required to be approved for sunlight resistance and approved for a wet location. Article 310-8-C & D This sunlight resistant rated wire will commonly have the words “sunlight resistant” written on the cable itself. If you are installing a cable or wire underground in a conduit that cable must be approved for a wet location having an initial “W” in its classification initials. Article 310-8-C If you are installing wiring as direct buried wire, then that wire or cable must have a “U” rating in its classification initials, such as UF or USE or URD. Article 310-B-1-D

If you are passing a non-metallic sheathed cable through a metal siding or wall covering, then you must use a rubber grommet or chase nipple where it passes through the metal to protected the plastic sheath of the cable from being cut by the metal. Article 336-6-B.

DESIGNING THE SERVICE TO A DETACHED GARAGE / SEPARATE METER OR POWER FED FROM THE MAIN DWELLING ?

You have several options and / or decisions to make on the power source, and design, of a service to a detached structure. We might consider the power source first. You must consider the frequency of use and the amount of electrical usage before you should design the type of service you might pick to supply electricity to your detached structure. One thing that you might consider are the probability of a minimum bill sent to you each month by your serving Utility Company, if you opt to have a separate meter serving your detached structure. Most Utility Companies will charge you both a construction charge for supplying a separate service to your structure, and a minimum bill each month regardless whether you use electricity in the detached structure, that month or not. You might want to check to see if the per kilowatt charge for the detached structure, and the per kilowatt charge for your dwelling are the same. You might find a substantial increase in the per kilowatt charge for the detached structure, than what they charge for your dwelling. It may even be a commercial rate of charge per kilowatts used, and / or for a minimum bill if no electricity is used. If you opt to install a separate meter you most likely will be charged a minimum bill for that service whether you use any electricity or not for the rest of the time you own the property, or as long as you keep the electricity on the detached structure. You also should confirm with your serving Utility company whether there will be any construction cost charged to you, by them, during the installation of that Utility power source serving that new detached garage. This may be a rather substantial amount of cost involved in their construction charges for that Utility company to energize a new meter base serving that detached garage. You should confirm any questions you have with your local Electrical Inspector, and your local Utility company before you finalize the plans of your detached structure.

If you supply the detached structure from your original dwelling, then there would be no monthly minimum charge involved from the Utility company, concerning that detached garage. If you supply the detached structure from your dwelling, then you should be conscience of the load capacity of your dwelling’s service panel, and whether the dwelling’s service is strong enough to supply the detached structure considering the extra load expected to be added to that dwelling’s service. Most dwelling services will be large enough to serve a detached garage for personal use, considering it is common that very little actual sustained electrical load is actually added by the adding of that detached garage to your dwelling’s service, normally. Any construction cost would have to be absorbed by you, whether the Utility Company serves the detached structure considering construction charges that may be charged, or if your dwelling serves the detached structure.

If you are using the new detached garage for business use, then you would want to talk to your accountant about the tax advantages. Most often the accountant is reluctant to take a tax credit for a detached structure that is being served electrically from your dwelling. It is hard to defend the exact amount of electric usage tax credit when the electrical cost is absorbed into your dwelling’s total electrical cost. You might want to consider paying the minimum bill of the separate meter to use the electrical usage as a tax deduction. I am told that the separated services metered by the Utility company as two different services, would be much easier to defend a tax credit from that detached garage’s electrical usage on your commercial taxes. Please check with your accountant to help you make this decision.

SIZING THE SERVICE FOR YOUR DETACHED GARAGE;

The following is an attempt to provide several scenarios involving electric usage of a detached structure. The first thing to consider is what the maximum electrical loads are planned that will truly be utilized in the detached structure at any one given time. In deciding this maximum, you must consider, truly, how many people will be using electricity in that detached structure at the same time.

You could have a total of 600 amps or more worth of individual motor loads in the detached structure, and only need a 60 amp service considering the fact that only one person would be using the equipment at a time, therefore only one motor would be used at any given time, normally. You may have 600 amps or more worth of motors, but you most likely will only be using one motor at a time if you are the only one working in the structure.

You must keep in consideration any automatic start equipment such as air compressors etc. that would likely be running at the same time you may be using a second motor to perform work. When you size the service requirements involved to serve a detached structure, you should be truthful with yourself as to the likely maximum electrical load applied to that service at any one given time frame. How many machines are you going to operate at once ? Article 220-21

EXAMPLES DESCRIBED CONCERNING DIFFERENT SERVICE DESIGNS FOR A DETACHED GARAGE;

Most people over-wire their detached garage and spend money on a service 10 times larger than is needed, then don’t have the money to install the equipment they want in the structure when they have way more than enough electricity available to run that equipment. Don’t under rate, but also don’t over rate your detached garage power supply.

Example # 1 If you are only going to have several convenience outlets in the detached structure with some lighting to see while you work but nothing else is planned, you might consider a special application allowing for a single 12 Ga. 20 amp circuit coming from the dwelling to the detached garage. This 120 volt {1 circuit} could most likely run a freezer or refrigerator and lighting and maybe one power saw or power drill etc. Most detached garages would fit in this category.

Example # 2 If you are only going to have several convenience outlets in the detached structure with some lighting to see while you work, and maybe an air compressor, and / or an electric range or welder and maybe one power tool but nothing else planned, then a 220 volt 60 amp service would probably be plenty large enough to serve this type of load, considering the intermittent usage of the equipment.

Example # 3 If you are only going to have several convenience outlets in the detached structure with some lighting to see while you work, and maybe an automatically operated air compressor and an electric range and a welder and maybe some power tools but nothing else planned, and with a couple of people working at the same time, then a 100 amp service may be required.

Example # 4 If you are only going to have several convenience outlets in the detached structure with only some lighting to see while you work, and maybe an automatically controlled air compressor and / or an electric range or welder and maybe several power tools [like planers, table saws, etc.], and two or more people running the machinery at the same time then a 200 amp service may be required.

You just have to be honest with yourself and don’t spend money on a size service that you won’t use. If you have questions the section called “Calculating the demand load part two” explaining the use of Article 220 of the NEC and showing a format to perform that calculation will tell you the minimum service size. You may even be able to have an electrician or the local Inspector calculate the minimum service size for you.

If you have question as to whether your dwelling service is large enough to serve the detached structure, feel free to call the Code Enforcement Div., in your area, or ask for an estimate from an electrical contractor, and often times they will calculate the minimum service size for you for both the dwelling with the detached structure load added to that dwelling service, or for a separate service fed detached garage. Just be able to provide the square footage, a list of the fixed equipment you have in your dwelling and the type of heat, cooking range, and type clothes dryer, and often times they will calculate the minimum service size dwelling’s service size and for your detached structure.

Please keep in mind to have available for the calculations a list of only fixed appliances and single circuits involved. Convenience outlets and general lighting is already calculated in the demand load calculation as per Table 220/3/B of the NEC in direct relationship to the type of usage and the square footage of your structure. Be sure to inform he or she that is calculating that demand load including your detached garage as to how many people will be working in that detached garage as one given time.

If you opt to supply the detached structure with the utility company serving a meter base on the structure, then you might want to refer to the link in this site referring to wiring a Service or Meter base for that service design.

DESIGNING A SERVICE TO THE DETACHED GARAGE USING A COMMON SERVICE FROM THE MAIN DWELLING’S SERVICE;

If you opt to supply the detached structure from your dwelling’s service supply, then the following might be of some help to you.

Before you proceed further with this article. Please be informed that the white wire is either a grounded or neutral conductor. A neutral carries the unbalanced load of two hot feeders. A grounded conductor is only the return path back to the panel if only one hot conductor is served by that grounded conductor.

All grounded conductors or neutrals must be insulated and identified with a color of white or gray. Article 200-6-A

A Grounding conductor is the equipment grounding conductor or the grounding electrode conductor supplying the structure from the grounding electrode system. A grounding conductor must be identified with a color of green or be bare and without insulation. Article 250-119

An ungrounded [hot] conductor may be any color available except white, gray, green, or bare.

Special Notes: A grounded conductor [is a current carrying conductor] {white or gray} (neutral or return path of a circuit) must be insulated except that section of the conductor that is isolated in free air as a duplex, triplex, or quadraplex, and is a service entrance neutral conductor on the line side of a main service rated panel. Articles 230-30 & 230-41 & 250-140 & 250-184 and many more Articles in the NEC.

A grounding conductor [is a non-current carrying conductor] {green or bare} (bonding ground or equipment ground) Article 250-119

Special Notes: There are a few exceptions such as Article 547 for agricultural buildings concerning livestock requiring insulated grounding electrode conductors. Also special wiring considerations must be considered such as PVC conduit or NMC cable {UF cable} if concentrations of animal excrement are present. If you have this scenario or suspect you may have this scenario then contact your local AHJ {Electrical Inspector} to confirm your wiring style before you install wiring in that agricultural style building

DESIGNING THE SERVICE TO THAT DETACHED GARAGE WHETHER A SEPARATE METERED SYSTEM OR FED FROM A COMMON SERVICE OF THE MAIN DWELLING’S SERVICE;

You have several options in the designs to supply power to the detached structure from your dwelling.

You should also refer to a link in this site called “WIRING A SERVICE” for details involving services, and common services, serving two or more buildings or structures. There is a detailed section included at that link providing the explanations that you may desire related to the service in the dwelling or in the detached structure or both.

PICTORIAL EXAMPLE OF ONE SINGLE CIRCUIT 120 VOLT 15 OR 20 AMP BRANCH CIRCUIT WITH OVERHEAD CONDUCTORS SUPPLYING THE DETACHED STRUCTURE

Note # 1 – All risers with weather heads that is installed above a roof must be substantial in strength installed so that there is a minimum clearance of at least 18” between the point of attachment and the roof itself. Article 230-24-A-Exception 3 The riser may rise above the roof a maximum of 5’ without a form of support to the roof. Rigid = Article 346-12-A Intermediate metal conduit = Article 345-12-A If more than 5’ is above the roof, then a normal method used as support for that riser to the roof would be a pair of guy wires in a “V” pattern attached at the same point on the riser, and spread out in the “V” pattern going away from the direction the overhead wire to the Utility Company is installed. These guy wires would be attached to the riser with a pipe clamp style porcelain knob attached to the riser conduit, and then lag bolt style eye bolts screwed into solid wood, usually through the roofing into a rafter. Article 225-17 & 230-28 Remember to use a roof boot for the riser to seal out weather where that riser passes through your roof, and a type of pitch around those eye bolts penetrating that roofing.

Note # 2 – A grounding electrode conductor is the sole connection between the grounding electrode {usually a ground rod} and the main panel of that structure that grounding electrode serves. The minimum size grounding electrode conductor recognized as a grounding electrode conductor is a # 8 copper. Article 250-66 The maximum size grounding electrode conductor required for a made electrode is a # 6 copper. Article 250-66-A No aluminum conductor may be used for grounding in direct contact with the earth. Article 250-64-A The minimum grounding electrode {made electrode such as a commercially made ground rod} allowed is a ½” factory made grounding electrode that is ½” in diameter X 8’ in length Article 250-52.

Note # 3 – Over head conductors installed in the air {aerial wiring} must be a minimum of 10’ above finished grade at its lowest swag of the aerial wire, if no vehicular traffic can travel under that aerial conductor. Aerial wires must be a minimum of 12’ above finished grade at its lowest swag of the aerial wire, if vehicular traffic may pass under that aerial conductor, but only on private land. Aerial wires must be a minimum of 18’ above finished grade at its lowest swag, if that aerial wire is installed over any street or alley. Article 225-18.

If triplex is used as commonly installed for this purpose, then #6 aluminum is the smallest aluminum aerial conductor allowed to be installed that is ran a length of 50’ or more. Article 225-6

When aerial conductors are installed to feed a 120 volt service with an equipment grounding conductor installed with that feeder then one black wire must be used as a hot conductor, one black wire must be re-identified as a white or gray wire, identified at the ends of that black wire being used as the neutral conductor. Article 200-6-A-2 & 4 Then the bare wire must be used as the equipment grounding conductor. Article 250-119

Note # 4 – A non fused switching device such as a 20 amp single pole switch, or a garage disconnect is allowed to be used as the form of disconnect in this detached garage being fed by a single 120 volt feeder with an equipment grounding conductor installed with that feeder. This disconnect or switch may be installed either outside and weatherproof Article 225-32 and 373-2 or nearest the point of entrance of that feeder inside and not weatherproof. Article 225-32 and 225-39 and 225-31

Note # 5 – An Overhead feeder should be triplex when feeding a detached garage with a single circuit 120 volt with equipment grounding conductor. This triplex must have a steel core messenger cable to support the aerial conductors, if 50’ or more in length. Article 225-6 This triplex must be connected to a porcelain knob on both ends of that aerial conductor at both structure’s point of attachment. Article 225-17 & 225-27 A # 6 Ga. aluminum triplex is normally the smallest triplex available in the open market. This size conductor has plenty of ampacity capacity to serve as this feeder whether 120 volt and 15 amp, or 120 volt and 20 amp, or even 30 amps if with an overcurrent device in the detached garage panel is installed to fuse down that single circuit feeding that garage. Remember that 15 or 20 amps is the maximum ampacity allowed for that single circuit feeding that garage if a multi-outlet branch circuit or duplex receptacles are used on that single branch circuit allowed in this wiring scenerio. Maximum branch circuit size to a general use 15 or 20 amp duplex receptacle device is 20 amps. Article 210-21-B-3 No part of this feeder from the breaker in the dwelling to the disconnect form in that detached garage may be rated in ampacity that is smaller than the overcurrent device {breaker or fuse} protecting that feeder on its line side located in the dwelling’s panel. Article 210-19 & 215-2 & 220-3 & 220-10 & 240-3 & 240-6 The minimum size of a single 120 volt branch circuit serving that detached structure is 15 amps Article 230-79-A, and the maximum size of that single circuit would be 30 amps due to available breakers in single pole design. Article 230-79-B Remember 30 amps is not allowed on 15 or 20 amp duplex receptacles or multi-outlet circuits. Article 210-21-B-2 If you install two circuits, then you should refer to the 30 amp drawings found later in this article. Article 230-79-B If you install a 15 amp breaker in the dwelling, then you may use a 14/2wGrnd UF cable from that dwelling’s panel to that weather head, and then also from the detached garage weather head to the garage disconnect, you may use the same 14/2wGrnd UF cable. If a 20 amp breaker in the dwelling protecting that circuit, then 12/2wGrnd UF cable is used in both buildings. If 30 amp breaker in the dwelling protecting that circuit, then 10/2wGrnd UF cable is used in both buildings. Article 240-3-D for ampacity ratings and 310-8-D for sunlight resistant requirements.

DO NOT USE EMT {electrical metallic tubing} IN DIRECT CONTACT WITH EARTH. Article 331-4-A-5.

Note # 6 – When the detached garage disconnect is supplied by a feeder that has an equipment grounding conductor ran from the main structure {usually dwelling} to the detached garage then the neutral bar and equipment grounding bar must be kept separated. Article 250-32-B-1 The equipment grounding bar must have a main bonding jumper connecting that equipment grounding bar to the metal of the panel box. Article 250-104-E The neutral bar must be kept isolated from the metal of the panel box and also the equipment grounding bar. Article 250-32-B-1

Note # 7 - Special note; In this drawing with only one single circuit feeding that detached garage, then no new electrical grounding system {usually a ground rod} is required to be installed at that detached garage. Article 250-32-Exception

Note # 8 – Load side of disconnect serving the branch circuit wiring in detached garage itself. This switching device or disconnect is where you start wiring the inside of your garage from, normally using nonmetallic sheathed cable. However there are many wiring styles such as conduit etc. that is allowed to wire the inside of this detached garage.

PICTORIAL EXAMPLE OF ONE SINGLE CIRCUIT 120 VOLT 15 OR 20 AMP BRANCH CIRCUIT WITH UNDERGROUND CONDUCTORS SUPPLYING THE DETACHED STRUCTURE

Note # 1 – A grounding electrode conductor is the sole connection between the grounding electrode {usually a ground rod}, and the main panel of that structure that grounding electrode serves. The minimum size grounding electrode conductor recognized as a grounding electrode conductor is a # 8 copper. Article 250-66 The maximum size grounding electrode conductor required for a made electrode is a # 6 copper. Article 250-66-A No aluminum conductor may be used for grounding in direct contact with the earth. Article 250-64-A The minimum grounding electrode {made electrode such as a commercially made ground rod} allowed is a ½” factory made grounding electrode that is ½” in diameter X 8’ in length Article 250-52.

Note # 2 –A non fused switching device or a garage disconnect is allowed to be used as the form of disconnect in this detached garage being fed by a single 120 volt feeder, with an equipment grounding conductor installed, with that feeder. This disconnect or switch may be installed either outside and weatherproof Article 225-32 and 373-2 or nearest point of entrance of that feeder inside and not weatherproof. Article 225-32 and 225-39 and 225-31

Note # 3 – When the detached garage disconnect is supplied by a feeder that has an equipment grounding conductor ran from the main structure {usually dwelling} to the detached garage, then the neutral bar, and equipment grounding bar must be kept separated. Article 250-32-B-1 The equipment grounding bar must have a main bonding jumper connecting that equipment grounding bar to the metal of the panel box. Article 250-104-E The neutral bar must be kept isolated from the metal of the panel box, and also the equipment grounding bar. Article 250-32-B-1

Note # 4 - Special note; In this drawing with only one single circuit feeding that detached garage, then no new electrical grounding system {usually a ground rod} is required to be installed at that detached garage. Article 250-32-Exception

Note # 5 – Minimum burial depth, in a residential setting, must be at least 18” deep, >unless in rigid or IMC threaded conduit these two conduits must be a minimum of 6” deep, if buried. Table 300-5. Also if this feeder is a maximum of 20 amps, and is GFI protected at the beginning of that underground feeder then the minimum depth may be 12” deep. Table 300-5

Note # 6 - No part of this feeder from the breaker in the dwelling to the disconnect form in that detached garage may be rated in ampacity that is smaller than the overcurrent device {breaker or fuse} protecting it in the dwelling’s panel. Article 210-19 & 215-2 & 220-3 & 220-10 & 240-3 & 240-6 The minimum size of a single 120 volt branch circuit serving that detached structure is 15 amps Article 230-79-A, and the maximum size of that single circuit would be 30 amps due to available breakers in single pole design. Article 230-79-B If you install two branch circuits in that detached garage disconnect, then you should refer to the 30 amp drawings located later in this article. Article 230-79-B If you install a 15 amp breaker in the dwelling, then you may use a 14/2wGrnd UF cable from that dwelling’s panel, non stop, to that garage disconnect. If a 20 amp breaker in the dwelling protecting that circuit, then 12/2wGrnd UF cable may be used, non stop, between both buildings. If 30 amp breaker in the dwelling protecting that circuit, then 10/2wGrnd UF cable may be used, non stop, between both buildings. Article 240-3-D for ampacity ratings and 310-8-D for sunlight resistant requirements. Remember 30 amps is not allowed on 15 or 20 amp duplex receptacles or multi-outlet circuits. Article 210-21-B-2 The maximum amp rating of a branch circuit using general use duplex receptacles is 20 amps. Article 210-21-B-3 Approved wiring for underground can be but not limited to Type UF cable if direct buried Article 339-3, or Type THWN, or THW, or TW if protected by a conduit. Article 310-13 You may install PVC schedule 40 when underground Article 347-2-G, or schedule 80 when exposed to physical damage Article 347-3-C, or rigid Article 346-3, or IMC conduits Article 345-3. Seal tight may be used for burial if listed for underground use and sunlight resistant Article 351-4-A-3. Type 2 non metallic seal tight may be used if listed for underground use Article 351-23-3 & . 251-22-2 Type 2 non metallic seal tight is a seal tight that is as described {A smooth inner surface with integral reinforcement within the conduit wall, designated as Type LFNC-B} if approved for direct burial and sunlight resistant. ENT {electrical nonmetallic tubing} is not allowed to be used in direct sunlight or if buried Article 331-4. ENT {electrical nonmetallic tubing} is not allowed to be used in direct sunlight or if buried Article 331-4. DO NOT USE EMT {electrical metallic tubing} IN DIRECT CONTACT WITH EARTH. Article 331-4-A-5.

Note # 7 – Load side of disconnect serving the branch circuit wiring in detached garage itself. This switching device or disconnect is where you start wiring the inside of your garage from, normally using nonmetallic sheathed cable. However there are many wiring styles allowed to wire the inside of this detached garage.

PICTORIAL EXAMPLE OF A TWO CIRCUIT 240 VOLT 15, 20 OR 30 AMP BRANCH CIRCUIT WITH OVER HEAD CONDUCTORS WITH AN EQUIPMENT GROUNDING CONDUCTOR RAN WITH THE FEEDER SUPPLYING THE DETACHED STRUCTURE

Special Note; Any detached structure that has an existing non-current carrying metallic path such as water pipes installed between the main structure and the detached structure must have an equipment grounding conductor installed with the feeders installed between the two buildings. Article 250-32-B-1 & 2

Note # 1 – All risers and weather heads that pass above the roof must be substantial in strength installed so that there is a minimum clearance of at least 18” between the point of attachment and the roof itself. Article 230-24-A-Exception 3 The riser may rise above the roof a maximum of 5’ without a form of support to the roof. Rigid = Article 346-12-A Intermediate metal conduit = Article 345-12-A If the riser is more than the 5’ maximum, a normal method used as support to the roof to support the riser would be a pair of guy wires in a “V” pattern attached at the same point on the riser and spread out in the “V” pattern going away from the direction the overhead wire to the Utility Company is installed. These guy wires would be attached to the riser with a pipe clamp style porcelain knob attached to the riser conduit, and then lag bolt style eye bolts screwed into solid wood, usually through the roofing into a rafter. Article 225-17 & 230-28 Remember to use a roof boot for the riser to seal out weather where that riser passes through your roof, and a type of pitch around those eye bolts penetrating that roofing.

Note # 2 – A grounding electrode conductor is the sole connection between the grounding electrode {usually a ground rod}, and the main panel of that structure that grounding electrode serves. The minimum size grounding electrode conductor recognized as a grounding electrode conductor is a # 8 copper. Article 250-66 The maximum size grounding electrode conductor required for a made electrode is a # 6 copper. Article 250-66-A No aluminum conductor may be used for grounding in direct contact with the earth. Article 250-64-A The minimum grounding electrode {made electrode such as a commercially made ground rod} allowed is a ½” factory made grounding electrode that is ½” in diameter X 8’ in length Article 250-52.

Note # 3 – Over head conductors installed in the air {aerial wiring} must be a minimum of 10’ above finished grade at its lowest swag of the aerial wire, if no vehicular traffic can travel under that aerial conductor. Aerial wires must be a minimum of 12’ above finished grade at its lowest swag of the aerial wire, if vehicular traffic may pass under that aerial conductor, but only on private land. Aerial wires must be a minimum of 18’ above finished grade at its lowest swag, if that aerial wire is installed over any street or alley. Article 225-18.

If quadraplex is used as commonly installed for this purpose, then #6 aluminum is the smallest aluminum aerial conductor allowed to be installed, that is ran a length of 50’ or more. Article 225-6

When quadraplex aerial conductors are installed to feed a 240 volt service with an equipment grounding conductor installed with that feeder, then two black {insulated} wires must be used as the two required hot conductors, The third black {insulated} wire must be re-identified as a white or gray wire at the ends of that black wire, which must be used as the neutral conductor. Article 200-6-A-2 & 4 Then the bare wire must be used as the equipment grounding conductor. Article 250-119

Note # 4 – A branch circuit is the circuits installed within a structure to serve your luminaries, {light fixtures} and your switches, and your receptacles.

The garage disconnect, if 30 amps, is required to be installed with a maximum of two branch circuit overcurrent devices {fuses or breakers} installed within that detached garage disconnect. This disconnect is allowed to be used as the form of main disconnect and is expected to contain the branch circuit overcurrent device {fuses or breakers} used for the maximum of two branch circuits, if 30 amp service, installed inside the detached garage. This detached garage being fed by two 120 volt feeders, a neutral and an equipment grounding conductor is creating a 240 volt service to that detached garage. If 30 amp rated this service must be a maximum of a 30 amp rated two circuit disconnect. This disconnect may be installed either outside and weatherproof Article 225-32 and 373-2or nearest point of entrance inside and not weatherproof. Article 225-32 and 225-39 and 225-31

Note # 5 – The Overhead feeder should be quadraplex when feeding a detached garage with two 120 volt hot conductors, one neutral conductor, and with an equipment grounding conductor. This quadraplex must have a steel core messenger cable to support the aerial conductors, if 50’, or more, in length. Article 225-6 A quadraplex is an aerial wire that contains three insulated wire, and one steel centered, bare messenger cable. This quadraplex must be connected to a porcelain knob on both ends of that aerial conductor, at both structure’s point of attachment. Article 225-17 & 225-27 A # 6 awg. aluminum quadraplex is normally the smallest quadraplex available on the open market. This size conductor has plenty of ampacity to serve as this feeder serving 240 volts with an equipment grounding conductor that is protected by a disconnect in the detached garage, and overcurrent device in the dwelling that is rated for 30 amps maximum. No part of this feeder from the overcurrent device installed at this feeders line side inside the dwelling, service panel, to the two circuit 30 amp rated disconnect form, installed in that detached garage, may be rated in ampacity that is smaller than the amp rating of the overcurrent device {breaker or fuse} protecting that feeder located in the dwelling’s panel on that feeders line side. Article 210-19 & 215-2 & 220-3 & 220-10 & 240-3 & 240-6 If you install more than two branch circuits in that panel installed in the detached garage, then you should refer to the 60 amp drawings found later in this article. Article 230-79-B

If you install a 30 amp 240 volt overcurrent device {fuse or breaker} in the dwelling, then you may use a copper 10/3wGrnd UF cable from that dwelling’s panel to that weather head located outside that dwelling supporting that aerial wire to that detached garage. Then you may also use a copper 10/3wGrnd UF cable from the detached garage weather head to the garage disconnect. Article 240-3-D for ampacity ratings and 310-8-D for sunlight resistant requirements. Be careful to use an alloy type compression connector that has a divider in that connector separating copper and aluminum conductors in that connector, where joining this copper UF cable to the aluminum quadraplex. Copper and aluminum will react chemically to each other causing a bad connection if the proper connecting device is used designed for this multi- metal connection. Article 110-14 DO NOT USE EMT {electrical metallic tubing} IN DIRECT CONTACT WITH EARTH. Article 331-4-A-5.

Note # 6 – When the detached garage disconnect is supplied by a feeder that has an equipment grounding conductor ran from the main structure {usually dwelling} to the detached garage, then the neutral bar, and equipment grounding bar must be kept separated. Article 250-32-B-1 The equipment grounding bar must have a main bonding jumper connecting that equipment grounding bar to the metal of the panel box. Article 250-102-E The neutral bar must be kept isolated from the metal of the panel box and the neutral must be kept separated from the equipment grounding bar. Article 250-32-B-1

Note # 7 – If there is no grounding electrode system serving the detached garage, then you must install a new grounding electrode system as described in Article 250-50. If none of those listed in Article 250-50 is available, then you may use a made electrode as found in Article 250-52. Article 250-50 lists any metal water pipe in direct contact with earth, any rebar in concrete, any grounding rings, and many more as an approved grounding electrode to be combined as a grounding electrode system. If available all of those grounding electrode sources listed in Article 250-50 must be connected together to make the grounding electrode system. Most likely, if you have a metal water pipe ran underground between the two buildings, then you have a water pipe in direct contact with earth and that metal water pipe, and any other grounding method listed in Article 250-50 must be connected together to make that grounding electrode system. If that metal water pipe is installed between the two buildings, then you must use that as part of the grounding electrode system but you must also supply a supplemental grounding electrode to back up that water pipe in case that metal water pipe is removed at a later date. Article 250-50-A-2 If any non current carrying metal connection is existing between that main building, and that detached garage, then you must install that equipment grounding conductor between the two buildings, with that feeder and as a part of that feeder installed between the two buildings. Article 250-32-B-1 & 2

Note # 8 – Load side of disconnect serving the branch circuit wiring in the detached garage itself. This switching device or disconnect is where you start wiring the inside of your garage from, normally using nonmetallic sheathed cable. However there are many wiring styles allowed to wire the inside of this detached garage.

PICTORIAL EXAMPLE OF A TWO CIRCUIT 240 VOLT 15, 20 OR 30 AMP BRANCH CIRCUIT WITH OVER HEAD CONDUCTORS WITHOUT AN EQUIPMENT GROUNDING CONDUCTOR RAN WITH THE FEEDER SUPPLYING THE DETACHED STRUCTURE

Special Note; Any detached structure that has an existing non-current carrying metallic path such as water pipes installed between the main structure and the detached structure must have an equipment grounding conductor installed with the feeders installed between the two buildings. Article 250-32-B-1 & 2

Note # 1 – All risers and weather heads that are passing above the roof must be substantial in strength installed so that there is a minimum clearance of at least 18” between the point of attachment and the roof itself. Article 230-24-A-Exception 3 The riser may rise above the roof a maximum of 5’ without a form of support to the roof. Rigid = Article 346-12-A Intermediate metal conduit = Article 345-12-A A common method used as support to the roof to support the riser would be a pair of guy wires in a “V” pattern attached at the same point on the riser and spread out in the “V” pattern going away from the direction the overhead wire to the Utility Company is installed. These guy wires would be attached to the riser with a pipe clamp style porcelain knob attached to the riser conduit and then lag bolt style eye bolts screwed into solid wood, usually through the roofing into a rafter. Article 225-17 & 230-28 Remember to use a roof boot for the riser to seal out weather where that riser passes through your roof, and a type of pitch around those eye bolts penetrating that roofing.

Note # 2 – A grounding electrode conductor is the sole connection between the grounding electrode {usually a ground rod}, and the main panel of that structure that grounding electrode serves. The minimum size grounding electrode conductor recognized as a grounding electrode conductor is a # 8 copper. Article 250-66 The maximum size grounding electrode conductor required for a made electrode is a # 6 copper. Article 250-66-A No aluminum conductor may be used for grounding in direct contact with the earth. Article 250-64-A The minimum grounding electrode {made electrode such as a commercially made ground rod} allowed is a ½” factory made grounding electrode that is ½” in diameter X 8’ in length Article 250-52.

Note # 3 – Over head conductors installed in the air {aerial wiring} must be a minimum of 10’ above finished grade at its lowest swag of the aerial wire, if no vehicular traffic can travel under that aerial conductor. Aerial wires must be a minimum of 12’ above finished grade at its lowest swag of the aerial wire, if vehicular traffic may pass under that aerial conductor but only on private land. Aerial wires must be a minimum of 18’ above finished grade at its lowest swag if that aerial wire is installed over any street or alley. Article 225-18.

If triplex is used as normally installed, then #6 aluminum is the smallest aluminum aerial conductor allowed to be installed that is ran a length of 50’ or more. Article 225-6

When aerial conductors are installed to feed a 240 volt service without an equipment grounding conductor installed with that feeder then two black {insulated} wires must be used as the two required hot conductors, The bare {messenger cable} wire may be used as the neutral conductor. Article 224-4 & 250-184 Exception 2

Note # 4 – A branch circuit is the circuits installed within a structure to serve your luminaries {light fixtures}, and your switches, and your receptacles.

The garage disconnect, if 30 amps, is required to be installed with a maximum of two branch circuits overcurrent devices {fuses or breakers} installed within that detached garage disconnect. This disconnect is allowed to be used as the form of main disconnect, and is expected to contain the branch circuit overcurrent device {fuses or breakers} used for the branch circuits installed inside the detached garage. This detached garage being fed by two 120 volt hot conductors, and a neutral is creating a 240 volt service to that detached garage. If 30 amp, rated this service must be a maximum of a 30 amp rated two branch circuit disconnect. This disconnect may be installed either outside and weatherproof Article 225-32 and 373-2or nearest point of entrance inside and not weatherproof. Article 225-32 and 225-39 and 225-31

Note # 5 – >The Overhead feeder should be triplex when feeding a detached garage with two 120 volt hot conductors, one neutral conductor, and without an equipment grounding conductor. This triplex must have a steel core messenger cable to support the aerial conductors, if 50’ or more in length. Article 225-6 A triplex is an aerial wire that contains two insulated wire and one steel centered, bare messenger cable. This triplex must be connected to a porcelain knob on both ends of that aerial conductor at both structure’s point of attachment. Article 225-17 & 225-27 A # 6 Ga. aluminum triplex is normally the smallest triplex available on the open market. This size conductor is plenty heavy enough in ampacity to serve as this feeder serving 240 volts without an equipment grounding conductor that is protected by a disconnect, and overcurrent device, rated for 30 amps maximum. No part of this feeder from the overcurrent device installed at this feeders line side inside the dwelling, service panel, to the two branch circuit 30 amp rated disconnect form, installed in that detached garage, may be rated in ampacity that is smaller than the amp rating of the overcurrent device {breaker or fuse} protecting that feeder located in the dwelling’s panel on that feeders line side. Article 210-19> & 215-2> & 220-3> & 220-10> & 240-3> & 240-6> If you install more than two branch circuits in the panel installed in that detached garage, then you should refer to the 60 amp drawings found later in this article. Article 230-79-B

If you install a 30 amp 240 volt overcurrent device {fuse or breaker} in the dwelling, then you may use a 10/3 UF cable, discarding the bare conductor of that 10/3 UF cable, from that dwelling’s panel to that weather head located outside that dwelling supporting that aerial wire to that detached garage. Then you may also use 10/3 UF cable, again discarding that bare conductor in that UF cable, from the detached garage weather head to the garage disconnect. Article 240-3-D for ampacity ratings and 310-8-D for sunlight resistant requirements. Be careful to use an alloy type compression connector that has a divider in that connector separating copper and aluminum conductors in that connector, where joining this copper UF cable to the aluminum quadraplex. Copper and aluminum will react chemically to each other causing a bad connection if the proper connecting device is used designed for this multi- metal connection. Article 110-14 >DO NOT USE EMT {electrical metallic tubing} IN DIRECT CONTACT WITH EARTH. Article 331-4-A-5.

Note # 6 – >When the detached garage disconnect is supplied by a feeder that has no equipment grounding conductor ran with that feeder, from the main structure {usually dwelling} to the detached garage, then the neutral bar, and equipment grounding bar must be joined or married together as one entity, usually by a jumper bar attached between the two bars or by a jumper bar connecting the neutral bar to the metal of that panel box and the grounding bar bolted directly to that metal of that panel box. Article 250-32-B-2 & 250-102-E The neutral bar must married or joined together with the metal of the panel box and also the equipment grounding bar. Article 250-32-B-2

Note # 7 – >If there is no grounding electrode system serving the detached garage, then you must install a new grounding electrode system as described in Article 250-50. If none of those listed in Article 250-50 is available then you may use a made electrode as found in Article 250-52. >Article 250-50 >lists any metal water pipe in direct contact with earth, any rebar in concrete, any grounding rings and many more as an approved grounding electrode to be used as a grounding electrode system. If available all of those grounding electrode sources listed in Article 250-50 must be connected together to make the grounding electrode system. REMEMBER THAT IF A NON CURRENT CARRYING METAL PATH EXISTS BETWEEN THE TWO BUILDINGS CONNECTING THE TWO BUILDINGS THEN YOU MUST INSTALL AN EQUIPMENT GROUNDING CONDUCTOR WITH THE FEEDER INSTALLED SERVING THAT SECOND BUILDING FORM THAT MAIN BUILDING. IF THIS NON CURRENT CARRYING METAL PATH EXISTS THEN REFER TO THE SECTION EXPLAINING HOW TO WIRE A DETACHED STRUCTURE WITH 30 AMPS MAXIMUM AND WITH AN EQUIPMENT GROUNDING CONDUCTOR RAN WITH THE FEEDERS BETWEEN BUILDINGS. LOCATED JUST BEFORE THIS SECTION. If you have a metal water pipe ran underground, but does not make contact between the two buildings, and if your metal water pipe, located at that detached structure, is in direct contact with earth, then that metal water pipe, and any other grounding method listed in Article 250-50 must be connected together to make that grounding electrode system. If that metal water pipe is installed in direct contact with the earth, but that water pipe is not installed connecting the two buildings, then you must use that water pipe in direct contact with earth as part of the grounding electrode system, but you must also supply a supplemental grounding electrode to back up that water pipe in case that metal water pipe is removed at a later date. Article 250-50-A-2 Remember, If any metal connection is existing between that main building and that detached garage then you must install that equipment grounding conductor between the two buildings with that feeder and as a part of that feeder installed between the two buildings. Article 250-32-B-1 & 2

Note # 8 – >Load side of disconnect serving the branch circuit wiring in detached garage itself. This switching device or disconnect is where you start wiring the inside of your garage from, normally using nonmetallic sheathed cable. However there are many wiring styles allowed to wire the inside of this detached garage.

PICTORIAL EXAMPLE OF A TWO CIRCUIT 240 VOLT 15, 20 OR 30 AMP BRANCH CIRCUIT WITH UNDERGROUND CONDUCTORS WITH AN EQUIPMENT GROUNDING CONDUCTOR RAN WITH THE FEEDER SUPPLYING THE DETACHED STRUCTURE

Note # 1 – A grounding electrode conductor is the sole connection between the grounding electrode {usually a ground rod}, and the main panel of that structure that the grounding electrode serves. The minimum size grounding electrode conductor recognized as a grounding electrode conductor is a # 8 copper. Article 250-66 The maximum size grounding electrode conductor required for a made electrode is a # 6 copper. Article 250-66-A No aluminum conductor may be used for grounding in direct contact with the earth. Article 250-64-A The minimum grounding electrode {made electrode such as a commercially made ground rod} allowed is a ½” factory made grounding electrode that is ½” in diameter X 8’ in length Article 250-52.

Note # 2 – A garage disconnect is allowed to be used as the form of disconnect in this detached garage being fed by two 120 volt hot conductors in the feeder with an insulated neutral and a bare equipment grounding conductor installed with that feeder. This disconnect may be installed either outside and weatherproof Article 225-32 and 373-2, or nearest point of entrance of that feeder inside, and not weatherproof. Article 225-32 and 225-39 and 225-31

Note # 3 – >When the detached garage disconnect is supplied by a feeder that has an equipment grounding conductor ran from the main structure {usually dwelling} to the detached garage, then the neutral bar, and equipment grounding bar must be kept separated. Article 250-32-B-1 The equipment grounding bar must have a main bonding jumper connecting that equipment grounding bar to the metal of the panel box. Article 250-104-E> The neutral bar must be kept isolated from the metal of the panel box, and also the equipment grounding bar. Article 250-32-B-1

Note # 4 - >If there is no grounding electrode system serving the detached garage, then you must install a new grounding electrode system as described in Article 250-50. If none of those listed in Article 250-50> is available, then you may use a made electrode as found in Article 250-52. Article 250-50 lists any metal water pipe in direct contact with earth, any rebar in concrete, any grounding rings, and many more as an approved grounding electrode to be used together to make the grounding electrode system. If available, all of those grounding electrode sources listed in Article 250-50 must be connected together to make the grounding electrode system. REMEMBER THAT IF A NON CURRENT CARRYING METAL PATH EXISTS BETWEEN THE TWO BUILDINGS CONNECTING THE TWO BUILDINGS, THEN YOU MUST INSTALL AN EQUIPMENT GROUNDING CONDUCTOR WITH THE FEEDER INSTALLED, SERVING THAT SECOND BUILDING FROM THAT MAIN BUILDING. IF THIS NON CURRENT CARRYING METAL PATH EXISTS, THEN REFER TO THE SECTION EXPLAINING HOW TO WIRE A DETACHED STRUCTURE WITH 30 AMPS MAXIMUM AND WITH AN EQUIPMENT GROUNDING CONDUCTOR RAN WITH THE FEEDERS BETWEEN BUILDINGS. If you have a metal water pipe ran underground, but that metal water pipe does not make contact between the two buildings, and if your metal water pipe, located at that detached structure, is in direct contact with earth, then that metal water pipe, and any other grounding method listed in Article 250-50 must be connected together to make that grounding electrode system. If that metal water pipe is installed in direct contact with the earth, but not installed connecting the two buildings, then you must use that metal water pipe in direct contact with earth as part of the grounding electrode system, but you must also supply a supplemental grounding electrode to back up that water pipe in case that metal water pipe is removed at a later date. Article 250-50-A-2> Remember, If any metal connection is existing between that main building and that detached garage then you must install that equipment grounding conductor between the two buildings with that feeder and as a part of that feeder installed between the two buildings. Article 250-32-B-1 & 2

Note # 5 – Minimum burial depth, in a residential setting, must be at least 18” deep, unless in rigid or IMC threaded conduit these two conduits must be a minimum of 6” deep, if buried. Table 300-5.

Note # 6 - No part of this feeder from the breaker in the dwelling to the disconnect form in that detached garage may be rated in ampacity that is smaller than the overcurrent device {breaker or fuse} protecting that feeder in the dwelling’s panel. Article 210-19 & 215-2 & 220-3 & 220-10 & 240-3 & 240-6. The 30 amps feeder must have a maximum of two 120 volt branch circuits in that disconnect installed in the detached garage. If you install three or more branch circuits, then you should refer to the 60 amp drawings found later in this article. Article 230-79-B If you install a 30 amp breaker 240 volt in the dwelling, then you may use a 10/3wGrnd UF cable from that dwelling’s panel non stop to that garage disconnect. Approved wiring for underground can be but not limited to Type UF cable if direct buried Article 339-3, or Type THWN, or THW, or TW if protected by a conduit. Article 310-13 You may install PVC schedule 40 when underground Article 347-2-G, or schedule 80 when exposed to physical damage Article 347-3-C, or rigid Article 346-3, or IMC conduits Article 345-3. Seal tight may be used for burial if listed for underground use Article 351-4-A-3. Type 2 non metallic seal tight may be used if listed for underground use Article 351-23-3 & . 251-22-2 Type 2 non metallic seal tight is a seal tight that is as described {A smooth inner surface with integral reinforcement within the conduit wall, designated as Type LFNC-B} if approved for direct burial and sunlight resistant. ENT {electrical nonmetallic tubing} is not allowed to be used in direct sunlight or if buried Article 331-4. ENT {electrical nonmetallic tubing} is not allowed to be used in direct sunlight or if buried Article 331-4. DO NOT USE EMT {electrical metallic tubing} IN DIRECT CONTACT WITH EARTH. Article 331-4-A-5.

Note # 7 – Load side of disconnect serving the branch circuit wiring in detached garage itself. This switching device or disconnect is where you start wiring the inside of your garage from, normally using nonmetallic sheathed cable. However there are many wiring styles allowed to wire the inside of this detached garage.

PICTORIAL EXAMPLE OF A GARAGE PANEL WITH 3 OR MORE CIRCUITS 240 VOLT 60 AMP, 100 AMP, 200 AMP BRANCH CIRCUIT WITH OVER HEAD CONDUCTORS WITH AN EQUIPMENT GROUNDING CONDUCTOR RAN WITH THE FEEDER SUPPLYING THE DETACHED STRUCTURE

Special Note; Any detached structure that has an existing non-current carrying metallic path such as water pipes installed between the main structure and the detached structure must have an equipment grounding conductor installed with the feeders installed between the two buildings. Article 250-32-B-1 & 2

Note # 1 – All risers and weather heads that is passing above the roof must be substantial in strength installed so that there is a minimum clearance of at least 18” between the point of attachment and the roof itself. Article 230-24-A-Exception 3 The riser may rise above the roof a maximum of 5’ without a form of support to the roof. Rigid = Article 346-12-A Intermediate metal conduit = Article 345-12-A If the riser is more than the 5’ maximum, a normal method used as support to the roof to support the riser would be a pair of guy wires in a “V” pattern attached at the same point on the riser, and spread out in the “V” pattern going away from the direction the overhead wire to the Utility Company is installed. These guy wires would be attached to the riser with a pipe clamp style porcelain knob attached to the riser conduit and then lag bolt style eye bolts screwed into solid wood, usually through the roofing into a rafter. Article 225-17 & 230-28 Remember to use a roof boot for the riser to seal out weather where that riser passes through your roof, and a type of pitch around those eye bolts penetrating that roofing.

Note # 2 – A grounding electrode conductor is the sole connection between the grounding electrode {usually a ground rod}, and the main panel of that structure that grounding electrode serves. The minimum size grounding electrode conductor recognized as a grounding electrode conductor is a # 8 copper for 100 amps or less. Article 250-66 The maximum size grounding electrode conductor required for a made electrode is a # 6 copper for any size service. Article 250-66-A No aluminum conductor may be used for grounding in direct contact with the earth. Article 250-64-A The minimum grounding electrode {made electrode such as a commercially made ground rod} allowed is a ½” factory made grounding electrode that is ½” in diameter X 8’ in length Article 250-52.

Note # 3 – Over head conductors installed in the air {aerial wiring} must be a minimum of 10’ above finished grade at its lowest swag of the aerial wire, if no vehicular traffic can travel under that aerial conductor. Aerial wires must be a minimum of 12’ above finished grade at its lowest swag of the aerial wire, if vehicular traffic may pass under that aerial conductor, but only on private land. Aerial wires must be a minimum of 18’ above finished grade at its lowest swag, if that aerial wire is installed over any street or alley. Article 225-18.

If Qaudraplex is used as commonly installed for this purpose, then 3 awg aluminum for 60 amps Table 310-16, 2 awg aluminum for 100 amps Table 310-15-B-6 or 4/0 awg for 200 Table 310-15-B-6 amps is the smallest aluminum aerial conductor allowed to be installed.

When aerial conductors are installed to feed a 240 volt service with an equipment grounding conductor installed with that feeder, then two black {insulated} wires must be used as the two required hot conductors, The third black {insulated} wire must be re-identified as a white or gray wire at the ends of that black wire, which must be used as the neutral conductor. Article 200-6-A-2 & 4 Then the bare wire must be used as the equipment grounding conductor. Article 250-119

Note # 4 – A branch circuit is the circuits installed within a structure to serve your luminaries, {light fixtures} and your switches, and your receptacles.

The garage main panel, if 100 amps is allowed 24 branch circuits to be installed in that panel. If 200 amps is allowed 42 branch circuits in that panel. Article 384-15 This main panel may have a maximum of 6 single pole or 6 double pole breakers installed as a maximum in that panel without having a main disconnect for that panel. The 6 breakers whether single or double pole may act as six main disconnects as allowed serving a structure. Article 225-33 The main disconnect (s) serving this detached garage may be installed either outside and weatherproof Article 225-32 and 373-2or nearest point of entrance inside and not weatherproof. Article 225-32 and 225-39 and 225-31 These main disconnects must be grouped. Article 225-34

Note # 5 – The Overhead feeder should be quadraplex, when feeding a detached garage with two 120 volt hot conductors, one neutral conductor, and with an equipment grounding conductor. This quadraplex must have a steel core messenger cable to support the aerial conductors, if 50’, or more, in length. Article 225-6 A quadraplex is an aerial wire that contains three insulated wire, and one steel centered, bare messenger cable. This quadraplex must be connected to a porcelain knob on both ends of that aerial conductor, at both structure’s point of attachment. Article 225-17 & 225-27 A 3 awg aluminum for 60 amps, or a 2 awg aluminum for 100 amps or a 4/0 awg aluminum for 200 amps is normally the smallest quadraplex allowed for those size feeders and panels serving that detached garage. Please refer to the last picture in this article explaining an unlimited tap rule when designing your power source for any feeder serving a detached garage larger than 125 amps. A detached garage using a service larger than 125 amps will have to have its own power source coming from the main dwelling. The largest branch circuit overcurrent device designed to be installed in a normal house panel is 125 amp rated.

If you install an overcurrent device protecting that feeder to that detached garage that is over 125 amp in rating you have two points of interest that you should consider. Your overcurrent device most likely will be a second main disconnect installed inside that main structure, making two main disconnects in your main dwelling. The first disconnect would be your distribution main service panel for your dwelling, and the second would be the large disconnect for your feeder going to the detached garage. There is a main service rated panel that is rated for the main service rated panel serving your dwelling that you can install a component to the bottom of the buss of that panel that will accept the feeder going to your garage through your main dwelling’s main service rated panel. This would create a set of lugs at the bottom of your house panel’s buss bar located inside your house panel where you can install your garage feeder. However if you use this feed through type main dwelling panel then that feeder going to that garage would have to be sized equal to the ampacity of the main overcurrent device of that panel serving your dwelling. This main serving your house panel also protects that feeder fed through that main service rated panel.

If you opt for a second main disconnect to serve your large feeder to that detached garage, remember that the two mains must be grouped. You must not install a main outside on that structure then a main inside of that structure. You would be violating the grouping of main disconnects as required in Article 225-34 and 230-72. The above consideration of mains and size of feeder going to the detached garage is why I suggested you check out the last drawing in this article considering the unlimited tap rule found in Article 240-21-B-5>

No part of this feeder from the overcurrent device installed at this feeders line side inside the dwelling’s service panel, to the disconnect form, installed in that detached garage, may be rated in ampacity that is smaller than the amp rating of the overcurrent device {breaker or fuse} protecting that feeder located in the dwelling’s panel on that feeders line side. Article 210-19 & 215-2 & 220-3 & 220-10 & 240-3 & 240-6, unless you refer to that last picture in this article that I mentioned concerning an unlimited tap rule.

If you install a 60 amp 240 volt overcurrent device {fuse or breaker} in the dwelling, then you may use 3- 6 awg copper or 4 awg aluminum THWN, THW, OR XHHW conductors protected by a conduit such as seal tight or Electrical Non-metallic Tubing from that dwelling’s panel to that weather head located outside that dwelling supporting that aerial wire to that detached garage. Type 2 non metallic seal tight may be used if listed for a building wiring method and approved for sunlight resistant. Article 351-23-3 & . 251-22-2 Type 2 non metallic seal tight is a seal tight that is as described {A smooth inner surface with integral reinforcement within the conduit wall, designated as Type LFNC-B}. ENT {electrical nonmetallic tubing} is not allowed to be used in direct sunlight or if buried Article 331-4. ENT {electrical nonmetallic tubing} is not allowed to be used in direct sunlight or if buried Article 331-4. Then you may also use the same wiring method from the detached garage weather head to the garage disconnect. Table 310-16 for ampacity ratings and 310-8-D for sunlight resistant requirements. Remember that you must run a fourth wire to be used as your equipment grounding conductor sized by Article 250-122 calling for a 10 awg copper or 8 awg aluminum.

If you install a 100 amp 240 volt overcurrent device {fuse or breaker} in the dwelling, then you may use 3- 4 awg copper or 2 awg aluminum THWN, THW, OR XHHW conductors protected by a conduit such as seal tight or Electrical Non-metallic Tubing from that dwelling’s panel to that weather head located outside that dwelling supporting that aerial wire to that detached garage. Then you may also use the same wiring method from the detached garage weather head to the garage disconnect. Table 310-16 for ampacity ratings and 310-8-D for sunlight resistant requirements. Remember that you must run a fourth wire to be used as your equipment grounding conductor sized by Article 250-122 calling for a 8 awg copper and a 6 awg aluminum.

If you install a 200 amp 240 volt overcurrent device {fuse or breaker} in the dwelling, then you may use a 3- 2/0 awg copper or 4/0 awg aluminum THWN, THW, OR XHHW conductors protected by a conduit such as seal tight or Electrical Non-metallic Tubing from that dwelling’s panel to that weather head located outside that dwelling supporting that aerial wire to that detached garage. Then you may also use the same wiring method from the detached garage weather head to the garage disconnect. Table 310-16 for ampacity ratings and 310-8-D for sunlight resistant requirements. Remember that you must run a fourth wire to be used as your equipment grounding conductor sized by Article 250-122 calling for a 6 awg copper and a 4 awg aluminum.

NOW THERE IS HEAVY CONTROVERSY WHETHER YOU MAY USE TABLE 310-15-B-6 WHILE INSTALLING FEEDERS TO A DETACHED RESIDENTIAL GARAGE. YOU SHOULD CONFIRM WITH YOUR LOCAL ELECTRICAL INSPECTOR TO CONFIRM IF YOU MUST USE TABLE 310-16 OR TABLE 310-15-B-6 WHEN INSTALLING A FEEDER BETWEEN THE MAIN DWELLING AND THE DETACHED GARAGE. TABLE 310-16 CALLS FOR THE FOLLOWING SIZES; 60 amp copper = 6 awg or 4 awg aluminum Table 310-16 & 240-3-B. 100 amp copper = 3 awg or 1 awg aluminum Table 310-16. 200 amp copper = 3/0 awg or 4/0 awg aluminum Table 310-16 & 240-3-B.

Be careful, here, you will find many nonmetallic sheathed cables installed between the house panel and the weather head outside supporting that overhead garage feeder. However you will be hard pressed finding a type NM or type SE cable that is approved both inside a dwelling without protection and exposed to the weather or sunlight while outside. You will either have to make an extra junction in the attic to go outside, or refer to what I suggested to meet minimum standards required as mentioned in the NEC. Don’t know that they make such a product that has all the ratings for sunlight and weather exposure, in a sheathed cable not requiring protection of a conduit, and still have three insulated conductors, and a bare equipment grounding conductor.

Also if you install copper conductors inside the structures, and are connecting to aluminum aerial conductors, then be sure to use a type split bolt that is an alloy style with a divider to separate the copper and aluminum at those bi-metal electrical connections. Copper and aluminum tend to react to each other and promote corrosion if they are in physical contact with each other. Article 110-14

DO NOT USE EMT {electrical metallic tubing} IN DIRECT CONTACT WITH EARTH. Article 331-4-A-5.

Note # 6 – When the detached garage service panel is supplied by a feeder that has an equipment grounding conductor ran from the main structure {usually dwelling} to the detached garage, then the neutral bar, and equipment grounding bar must be kept separated. Article 250-32-B-1 The equipment grounding bar must have a main bonding jumper connecting that equipment grounding bar to the metal of the panel box. Article 250-102-E The neutral bar must be kept isolated from the metal of the panel box and the neutral must be kept separated from the equipment grounding bar. Article 250-32-B-1

Note # 7 – If there is no grounding electrode system serving the detached garage, then you must install a new grounding electrode system as described in Article 250-50. If none of those listed in Article 250-50 is available, then you may use a made electrode as found in Article 250-52. Article 250-50 lists any metal water pipe in direct contact with earth, any rebar in concrete, any grounding rings, and many more as an approved grounding electrode to be combined as a grounding electrode system. If available all of those grounding electrode sources listed in Article 250-50 must be connected together to make the grounding electrode system. Most likely, if you have a metal water pipe ran underground between the two buildings, then you have a water pipe in direct contact with earth and that metal water pipe, and any other grounding method listed in Article 250-50 must be connected together to make that grounding electrode system. If that metal water pipe is installed between the two buildings, then you must use that as part of the grounding electrode system but you must also supply a supplemental grounding electrode to back up that water pipe in case that metal water pipe is removed at a later date. Article 250-50-A-2 If any non current carrying metal connection is existing between that main building, and that detached garage, then you must install that equipment grounding conductor between the two buildings, with that feeder and as a part of that feeder installed between the two buildings. Article 250-32-B-1 & 2

Note # 8 – Load side of disconnect serving the branch circuit wiring in the detached garage itself. This service panel installed inside your detached garage is where you start wiring the branch circuits serving the inside of your garage from, normally using nonmetallic sheathed cable. However there are many wiring styles allowed to wire the inside of this detached garage.

PICTORIAL EXAMPLE OF A GARAGE PANEL WITH 3 OR MORE CIRCUITS 240 VOLT 60 AMP, 100 AMP, 200 AMP BRANCH CIRCUIT WITH OVER HEAD CONDUCTORS WITHOUT AN EQUIPMENT GROUNDING CONDUCTOR RAN WITH THE FEEDER SUPPLYING THE DETACHED STRUCTURE

Special Note; Any detached structure that has an existing non-current carrying metallic path such as water pipes installed between the main structure, and the detached structure must have an equipment grounding conductor installed with the feeders installed between the two buildings. Article 250-32-B-1 & 2

Note # 1 – All risers and weather heads that pass above the roof must be substantial in strength installed so that there is a minimum clearance of at least 18” between the point of attachment and the roof itself. Article 230-24-A-Exception 3 The riser may rise above the roof a maximum of 5’ without a form of support to the roof. Rigid = Article 346-12-A Intermediate metal conduit = Article 345-12-A A common method used as support to the roof to support the riser would be a pair of guy wires in a “V” pattern attached at the same point on the riser and spread out in the “V” pattern going away from the direction the overhead wire to the Utility Company is installed. These guy wires would be attached to the riser with a pipe clamp style porcelain knob attached to the riser conduit, and then lag bolt style eye bolts screwed into solid wood, usually through the roofing into a rafter. Article 225-17 & 230-28 Remember to use a roof boot for the riser to seal out weather where that riser passes through your roof, and a type of pitch around those eye bolts penetrating that roofing.

Note # 2 – A grounding electrode conductor is the sole connection between the grounding electrode {usually a ground rod} and the main panel of that structure that grounding electrode serves. The minimum size grounding electrode conductor recognized as a grounding electrode conductor is a 8 awg copper for 100 amps or less and 4 awg copper for 200 amps. Article 250-66 The maximum size grounding electrode conductor required for a made electrode is a 6 awg copper, no matter how large the service is. Article 250-66-A No aluminum conductor may be used for grounding in direct contact with the earth. Article 250-64-A The minimum grounding electrode {made electrode such as a commercially made ground rod} allowed is a ½” factory made grounding electrode that is ½” in diameter X 8’ in length Article 250-52.

Note # 3 – Over head conductors installed in the air {aerial wiring} must be a minimum of 10’ above finished grade at its lowest swag of the aerial wire, if no vehicular traffic can travel under that aerial conductor. Aerial wires must be a minimum of 12’ above finished grade at its lowest swag of the aerial wire, if vehicular traffic may pass under that aerial conductor but only on private land. Aerial wires must be a minimum of 18’ above finished grade at its lowest swag if that aerial wire is installed over any street or alley. Article 225-18.

If triplex is used as commonly installed for this purpose, then 3 awg aluminum for 60 amps Table 310-16, 2 awg aluminum for 100 amps Table 310-15-B-6 or 4/0 awg for 200 Table 310-15-B-6 amps is the smallest aluminum aerial conductor allowed to be installed.

When aerial conductors are installed to feed a 240 volt service, without an equipment grounding conductor installed with that feeder, then two black {insulated} wires must be used as the two required hot conductors, The bare {messenger cable} wire may be used as the neutral conductor. Article 224-4 & 250-184 Exception 2

Note # 4 – A branch circuit is the circuits installed within a structure to serve your luminaries {light fixtures}, and your switches, and your receptacles.

The garage main panel, if 100 amps is allowed 24 branch circuits to be installed in that panel. If 200 amps is allowed 42 branch circuits in that panel. Article 384-15 This main panel may have a maximum of 6 single pole or 6 double pole breakers installed as a maximum in that panel without having a main disconnect for that panel. The 6 breakers whether single or double pole may act as six main disconnects as allowed serving a structure. Article 225-33 The main disconnect (s) serving this detached garage may be installed either outside and weatherproof Article 225-32 and 373-2or nearest point of entrance inside and not weatherproof. Article 225-32 and 225-39 and 225-31 These main disconnects must be grouped. Article 225-34

Note # 5 – The Overhead feeder should be triplex when feeding a detached garage with two 120 volt hot conductors, one neutral conductor, and without an equipment grounding conductor. This triplex must have a steel core messenger cable to support the aerial conductors, if 50’ or more in length. Article 225-6 A triplex is an aerial wire that contains two insulated wire and one steel centered, bare messenger cable. This triplex must be connected to a porcelain knob on both ends of that aerial conductor at both structure’s point of attachment. Article 225-17 & 225-27 A 3 awg aluminum for 60 amps, or a 2 awg aluminum for 100 amps or a 4/0 awg aluminum for 200 amps is normally the smallest triplex allowed for those size feeders and panels serving that detached garage. Please refer to the last picture in this article explaining an unlimited tap rule when designing your power source for any feeder serving a detached garage larger than 125 amps. A detached garage using a service larger than 125 amps will have to have its own power panel coming from the main dwelling. The largest branch circuit overcurrent device designed to be installed in a normal house panel is 125 amp rated.

If you install an overcurrent device protecting that feeder to that detached garage that is over 125 amp in rating you have two points of interest that you should consider. Your overcurrent device most likely will be a second main disconnect installed inside that main structure, making two main disconnects in your main dwelling. The first disconnect would be your distribution main service panel for your dwelling, and the second would be the large disconnect for your feeder going to the detached garage. There is a main service rated panel that is rated for the main service rated panel serving your dwelling that you can install a component to the bottom of the buss of that panel that will accept the feeder going to your garage through your main dwelling’s main service rated panel. This would create a set of lugs at the bottom of your house panel’s buss bar located inside your house panel, where you can install your garage feeder. However if you use this feed through type main dwelling panel, then that feeder going to that garage would have to be sized equal to the ampacity of the main overcurrent device of that panel. This main serving your house panel also protects that feeder fed through that main service rated panel.

If you opt for a second main disconnect to serve your large feeder to that detached garage, remember that the two mains must be grouped. You must not install a main outside on that structure, then a main inside of that structure. You would be violating the grouping of main disconnects as required in Article 225-34 and 230-72. The above consideration of mains and size of feeder going to the detached garage is why I suggested you check out the last drawing in this article considering the unlimited tap rule found in Article 240-21-B-5

No part of this feeder from the overcurrent device installed at this feeders line side inside the dwelling, service panel, to the disconnect form, installed in that detached garage, may be rated in ampacity that is smaller than the amp rating of the overcurrent device {breaker or fuse} protecting that feeder located in the dwelling’s panel on that feeders line side. Article 210-19 & 215-2 & 220-3 & 220-10 & 240-3 & 240-6, unless you refer to that last picture in this article that I mentioned.

If you install a 60 amp 240 volt overcurrent device {fuse or breaker} in the dwelling, then you may use 3- 6 awg copper or 4 awg aluminum THWN, THW, OR XHHW conductors protected by a conduit such as seal tight or Electrical Non-metallic Tubing. Type 2 non metallic seal tight may be used if listed for underground use and sunlight resistant Article 351-23-3 & . 251-22-2 Type 2 non metallic seal tight is a seal tight that is as described {A smooth inner surface with integral reinforcement within the conduit wall, designated as Type LFNC-B}. ENT {electrical nonmetallic tubing} is not allowed to be used in direct sunlight or if buried Article 331-4. from that dwelling’s panel to that weather head located outside that dwelling supporting that aerial wire to that detached garage. Then you may also use the same wiring method from the detached garage weather head to the garage disconnect. Table 310-16 for ampacity ratings and 310-8-D for sunlight resistant requirements.

If you install a 100 amp 240 volt overcurrent device {fuse or breaker} in the dwelling, then you may use a 3- 4 awg copper or 2 awg aluminum THWN, THW, OR XHHW conductors protected by a conduit such as seal tight or Electrical Non-metallic Tubing from that dwelling’s panel to that weather head located outside that dwelling supporting that aerial wire to that detached garage. Then you may also use the same wiring method from the detached garage weather head to the garage disconnect. Table 310-16 for ampacity ratings and 310-8-D for sunlight resistant requirements.

If you install a 200 amp 240 volt overcurrent device {fuse or breaker} in the dwelling, then you may use 3- 2/0 awg copper or 4/0 awg aluminum THWN, THW, OR XHHW conductors protected by a conduit such as seal tight or Electrical Non-metallic Tubing from that dwelling’s panel to that weather head located outside that dwelling supporting that aerial wire to that detached garage. Then you may also use the same wiring method from the detached garage weather head to the garage disconnect. Table 310-16 for ampacity ratings and 310-8-D for sunlight resistant requirements.

NOW THERE IS HEAVY CONTROVERSY WHETHER YOU MAY USE TABLE 310-15-B-6 WHILE INSTALLING FEEDERS TO A DETACHED RESIDENTIAL GARAGE. YOU SHOULD CONFIRM WITH YOUR LOCAL ELECTRICAL INSPECTOR TO CONFIRM IF YOU MUST USE TABLE 310-16 OR TABLE 310-15-B-6 WHEN INSTALLING A FEEDER BETWEEN THE MAIN DWELLING AND THE DETACHED GARAGE. TABLE 310-16 CALLS FOR THE FOLLOWING SIZES; 60 amp copper = 6 awg or 4 awg aluminum Table 310-16 & 240-3-B. 100 amp copper = 3 awg or 1 awg aluminum Table 310-16. 200 amp copper = 3/0 awg or 4/0 awg aluminum Table 310-16 & 240-3-B.

Be careful, here, you will find many nonmetallic sheathed cables installed between the house panel and the weather head outside supporting that overhead garage feeder. However you will be hard pressed finding a type NM or type SE cable that is approved both inside a dwelling without protection and exposed to the weather or sunlight while outside. You will either have to make an extra junction in the attic to go outside or refer to what I suggested to meet minimum standards required as mentioned in the NEC. Don’t know that they make such a product that has all the ratings for sunlight and weather exposure, in a sheathed cable not requiring protection of a conduit, and still have three insulated conductors and a bare equipment grounding conductor. Notice that the bare of an SE cable must not be used as a grounded or neutral conductor while inside a building or structure. Article 383-3-B

Also if you install copper conductors inside the structures, and are connecting to aluminum aerial conductors, then be sure to use a type split bolt that is an alloy style with a divider to separate the copper and aluminum at those bi-metal electrical connections. Copper and aluminum tend to react to each other and promote corrosion if they are in physical contact with each other. Article 110-14

DO NOT USE EMT {electrical metallic tubing} IN DIRECT CONTACT WITH EARTH. Article 331-4-A-5.

Note # 6 – When the detached garage main panel is supplied by a feeder that has no equipment grounding conductor ran with that feeder, from the main structure {usually dwelling} to the detached garage, then the neutral bar, and equipment grounding bar must be joined or married together as one entity, usually by a jumper bar attached between the two bars or by a jumper bar connecting the neutral bar to the metal of that panel box and the grounding bar bolted directly to that metal of that panel box. Article 250-32-B-2 & 250-102-E The neutral bar must married or joined together with the metal of the panel box and also the equipment grounding bar. Article 250-32-B-2

Note # 7 – If there is no grounding electrode system serving the detached garage, then you must install a new grounding electrode system as described in Article 250-50. If none of those listed in Article 250-50 is available then you may use a made electrode as found in Article 250-52. Article 250-50 lists any metal water pipe in direct contact with earth, any rebar in concrete, any grounding rings and many more as an approved grounding electrode to be used as a grounding electrode system. If available all of those grounding electrode sources listed in Article 250-50 must be connected together to make the grounding electrode system. REMEMBER THAT IF A NON CURRENT CARRYING METAL PATH EXISTS BETWEEN THE TWO BUILDINGS CONNECTING THE TWO BUILDINGS THEN YOU MUST INSTALL AN EQUIPMENT GROUNDING CONDUCTOR WITH THE FEEDER INSTALLED SERVING THAT SECOND BUILDING FORM THAT MAIN BUILDING. IF THIS NON CURRENT CARRYING METAL PATH EXISTS THEN REFER TO THE SECTION EXPLAINING HOW TO WIRE A DETACHED STRUCTURE WITH 3 OR MORE BRACH CIRCUITS 60, 100, OR 200 AMP RATED AND WITH AN EQUIPMENT GROUNDING CONDUCTOR RAN WITH THE FEEDERS BETWEEN BUILDINGS. LOCATED JUST BEFORE THIS SECTION. If you have a metal water pipe ran underground, but does not make contact between the two buildings, and if your metal water pipe, located at that detached structure, is in direct contact with earth, then that metal water pipe, and any other grounding method listed in Article 250-50 must be connected together to make that grounding electrode system. If that metal water pipe is installed in direct contact with the earth, but that water pipe is not installed connecting the two buildings, then you must use that water pipe in direct contact with earth as part of the grounding electrode system, but you must also supply a supplemental grounding electrode to back up that water pipe in case that metal water pipe is removed at a later date. Article 250-50-A-2 Remember, If any metal connection is existing between that main building and that detached garage then you must install that equipment grounding conductor between the two buildings with that feeder and as a part of that feeder installed between the two buildings. Article 250-32-B-1 & 2

Note # 8 – Load side of disconnect serving the branch circuit wiring in detached garage itself. This switching device or disconnect is where you start wiring the inside of your garage from, normally using nonmetallic sheathed cable. However there are many wiring styles allowed to wire the inside of this detached garage.

PICTORIAL EXAMPLE OF A GARAGE PANEL WITH 3 OR MORE CIRCUITS 240 VOLT 60 AMP, 100 AMP, 200 AMP BRANCH CIRCUIT WITH UNDERGROUND CONDUCTORS WITH AN EQUIPMENT GROUNDING CONDUCTOR RAN WITH THE FEEDER SUPPLYING THE DETACHED STRUCTURE

Special Note; Any detached structure that has an existing non-current carrying metallic path such as water pipes installed between the main structure and the detached structure must have an equipment grounding conductor installed with the feeders installed between the two buildings. Article 250-32-B-1 & 2

Note # 1 – A grounding electrode conductor is the sole connection between the grounding electrode {usually a ground rod}, and the main panel of that structure that grounding electrode serves. The minimum size grounding electrode conductor recognized as a grounding electrode conductor is a # 8 copper for 100 amps or less. Article 250-66 The maximum size grounding electrode conductor required for a made electrode is a # 6 copper for any size service. Article 250-66-A No aluminum conductor may be used for grounding in direct contact with the earth. Article 250-64-A The minimum grounding electrode {made electrode such as a commercially made ground rod} allowed is a ½” factory made grounding electrode that is ½” in diameter X 8’ in length Article 250-52.

Note # 2 – A branch circuit is the circuits installed within a structure to serve your luminaries, {light fixtures}, and your switches, and your receptacles.

The garage main panel, if 100 amps is allowed 24 branch circuits to be installed in that panel. If 200 amps is allowed 42 branch circuits in that panel. Article 384-15 This main panel may have a maximum of 6 single pole or 6 double pole breakers installed as a maximum in that panel, without having a main disconnect installed in that panel. The 6 breakers whether single or double pole may act as six main disconnects as allowed serving a structure. Article 225-33 The main disconnect (s) serving this detached garage may be installed either outside and weatherproof Article 225-32 and 373-2 or nearest point of entrance inside and not weatherproof. Article 225-32 and 225-39 and 225-31 These main disconnects must be grouped. Article 225-34

Note # 3 – When the detached garage service panel is supplied by a feeder that has an equipment grounding conductor ran from the main structure {usually dwelling} to the detached garage, then the neutral bar, and equipment grounding bar must be kept separated. Article 250-32-B-1 The equipment grounding bar must have a main bonding jumper connecting that equipment grounding bar to the metal of the panel box. Article 250-102-E The neutral bar must be kept isolated from the metal of the panel box and the neutral must be kept separated from the equipment grounding bar. Article 250-32-B-1

Note # 4 - If there is no grounding electrode system serving the detached garage, then you must install a new grounding electrode system as described in Article 250-50. If none of those listed in Article 250-50 is available, then you may use a made electrode as found in Article 250-52. Article 250-50 lists any metal water pipe in direct contact with earth, any rebar in concrete, any grounding rings, and many more as an approved grounding electrode used connected together to make the grounding electrode system. If available, all of those grounding electrodes listed in Article 250-50 must be connected together to make the grounding electrode system. REMEMBER THAT IF A NON CURRENT CARRYING METAL PATH EXISTS BETWEEN THE TWO BUILDINGS CONNECTING THE TWO BUILDINGS, THEN YOU MUST INSTALL AN EQUIPMENT GROUNDING CONDUCTOR WITH THE FEEDER INSTALLED, SERVING THAT SECOND BUILDING FROM THAT MAIN BUILDING. IF THIS NON CURRENT CARRYING METAL PATH EXISTS, THEN REFER TO THE SECTION EXPLAINING HOW TO WIRE A DETACHED STRUCTURE WITH 30 AMPS MAXIMUM AND WITH AN EQUIPMENT GROUNDING CONDUCTOR RAN WITH THE FEEDERS BETWEEN BUILDINGS. If you have a metal water pipe ran underground, but that metal water pipe does not make contact between the two buildings, and if your metal water pipe, located at that detached structure, is in direct contact with earth, then that metal water pipe, and any other grounding method listed in Article 250-50 must be connected together to make that grounding electrode system. If that metal water pipe is installed in direct contact with the earth, but not installed connecting the two buildings, then you must use that metal water pipe in direct contact with earth as part of the grounding electrode system, but you must also supply a supplemental grounding electrode to back up that water pipe in case that metal water pipe is removed at a later date. Article 250-50-A-2 Remember, If any metal connection is existing between that main building and that detached garage then you must install that equipment grounding conductor between the two buildings with that feeder and as a part of that feeder installed between the two buildings. Article 250-32-B-1 & 2

Note # 5 – Minimum burial depth in a residential setting must be at least 18” deep unless in rigid or IMC threaded conduit these two conduits must be a minimum of 6” deep, if buried. Table 300-5.

Note # 6 - No part of this feeder from the breaker in the dwelling to the disconnect form in that detached garage may be rated in ampacity that is smaller than the overcurrent device {breaker or fuse} protecting that feeder in the dwelling’s panel. Article 210-19 & 215-2 & 220-3 & 220-10 & 240-3 & 240-6 If you install a 60 amp breaker 240 volt in the dwelling, then you may use a 6/3wGrnd UF copper cable from that dwelling’s panel to that garage disconnect. If you install a 100 amp breaker 240 volt in the dwelling, then you may use a 2 awg four wire URD aluminum cable from that dwelling’s panel to that garage disconnect. Article 338-3 If you install a 200 amp breaker 240 volt in the dwelling, then you may use a 2/0 awg four wire URD aluminum cable from that dwelling’s panel to that garage disconnect. Article 338-3 Approved wiring for underground can be but not limited to Type UF cable or URD cable if direct buried Article 338-3, or Type THWN, or THW, or TW if protected by a conduit. Article 310-13 You may install PVC schedule 40 when underground Article 347-2-G, or schedule 80 when exposed to physical damage Article 347-3-C, or rigid Article 346-3, or IMC conduits Article 345-3. Seal tight may be used for burial if listed for underground use Article 351-4-A-3. Type 2 non metallic seal tight may be used if listed for underground use as direct burial and sunlight resistant. Article 351-23-3 & . 251-22-2 Type 2 non metallic seal tight is a seal tight that is as described {A smooth inner surface with integral reinforcement within the conduit wall, designated as Type LFNC-B}. ENT {electrical nonmetallic tubing} is not allowed to be used in direct sunlight or if buried Article 331-4. ENT {electrical nonmetallic tubing} is not allowed to be used in direct sunlight or if buried Article 331-4. If you install the above conductors with a conduit protection then you must install two black wires, one white or gray wire and one green of bare wire. If the conduit is metal the metal the metal conduit may be used instead of the green or bare wire as the equipment grounding conductor. The minimum size conductors are as follows; 60 amp copper = 6 awg or 4 awg aluminum Table 310-16 & 240-3-B. 100 amp copper = 4 awg or 2 awg aluminum Table 310-15-B-6. 100 amp copper = 2/0 awg or 4/0 awg aluminum Table 310-15-B-6.

NOW THERE IS HEAVY CONTROVERSY WHETHER YOU MAY USE TABLE 310-15-B-6 WHILE INSTALLING FEEDERS TO A DETACHED RESIDENTIAL GARAGE. YOU SHOULD CONFIRM WITH YOUR LOCAL ELECTRICAL INSPECTOR TO CONFIRM IF YOU MUST USE TABLE 310-16 OR TABLE 310-15-B-6 WHEN INSTALLING A FEEDER BETWEEN THE MAIN DWELLING AND THE DETACHED GARAGE. TABLE 310-16 CALLS FOR THE FOLLOWING SIZES; 60 amp copper = 6 awg or 4 awg aluminum Table 310-16 & 240-3-B. 100 amp copper = 3 awg or 1 awg aluminum Table 310-16. 200 amp copper = 3/0 awg or 4/0 awg aluminum Table 310-16 & 240-3-B.

DO NOT USE EMT {electrical metallic tubing} IN DIRECT CONTACT WITH EARTH. Article 331-4-A-5.

Note # 7 – Load side of disconnect serving the branch circuit wiring in the detached garage itself. This service panel installed inside your detached garage is where you start wiring the branch circuits serving the inside of your garage from, normally using nonmetallic sheathed cable. However there are many wiring styles allowed to wire the inside of this detached garage.

PICTORIAL EXAMPLE OF A GARAGE PANEL WITH 3 OR MORE CIRCUITS 240 VOLT 60 AMP, 100 AMP, 200 AMP BRANCH CIRCUIT WITH UNDERGROUND CONDUCTORS WITHOUT AN EQUIPMENT GROUNDING CONDUCTOR RAN WITH THE FEEDER SUPPLYING THE DETACHED STRUCTURE

Special Note; Any detached structure that has an existing non-current carrying metallic path such as water pipes installed between the main structure and the detached structure must have an equipment grounding conductor installed with the feeders installed between the two buildings. Article 250-32-B-1 & 2

Note # 1 – A grounding electrode conductor is the sole connection between the grounding electrode {usually a ground rod}, and the main panel of that structure that grounding electrode serves. The minimum size grounding electrode conductor recognized as a grounding electrode conductor is a 8 awg copper for 100 amps or less. Article 250-66 The maximum size grounding electrode conductor required for a made electrode is a 6 awg copper for any size service. Article 250-66-A No aluminum conductor may be used for grounding in direct contact with the earth. Article 250-64-A The minimum grounding electrode {made electrode such as a commercially made ground rod} allowed is a ½” factory made grounding electrode that is ½” in diameter X 8’ in length Article 250-52.

Note # 2 – A branch circuit is the circuits installed within a structure to serve your luminaries, {light fixtures}, and your switches, and your receptacles.

The garage main panel, if 100 amps is allowed 24 branch circuits to be installed in that panel. If 200 amps is allowed 42 branch circuits in that panel. Article 384-15 This main panel may have a maximum of 6 single pole or 6 double pole breakers installed as a maximum in that panel, without having a main disconnect installed in that panel. The 6 breakers whether single or double pole may act as six main disconnects as allowed serving a structure. Article 225-33 The main disconnect (s) serving this detached garage may be installed either outside and weatherproof Article 225-32 and 373-2 or nearest point of entrance inside and not weatherproof. Article 225-32 and 225-39 and 225-31 These main disconnects must be grouped. Article 225-34

Note # 3 – When the detached garage main panel is supplied by a feeder that has no equipment grounding conductor ran with that feeder, from the main structure {usually dwelling} to the detached garage, then the neutral bar, and equipment grounding bar must be joined or married together as one entity, usually by a jumper bar attached between the two bars or by a jumper bar connecting the neutral bar to the metal of that panel box and the grounding bar bolted directly to that metal of that panel box. Article 250-32-B-2 & 250-102-E The neutral bar must married or joined together with the metal of the panel box and also the equipment grounding bar. Article 250-32-B-2

Note # 4 - If there is no grounding electrode system serving the detached garage, then you must install a new grounding electrode system as described in Article 250-50. If none of those listed in Article 250-50 is available, then you may use a made electrode as found in Article 250-52. Article 250-50 lists any metal water pipe in direct contact with earth, any rebar in concrete, any grounding rings, and many more as an approved grounding electrode used connected together to make the grounding electrode system. If available, all of those grounding electrodes listed in Article 250-50 must be connected together to make the grounding electrode system. REMEMBER THAT IF A NON CURRENT CARRYING METAL PATH EXISTS BETWEEN THE TWO BUILDINGS CONNECTING THE TWO BUILDINGS, THEN YOU MUST INSTALL AN EQUIPMENT GROUNDING CONDUCTOR WITH THE FEEDER INSTALLED, SERVING THAT SECOND BUILDING FROM THAT MAIN BUILDING. IF THIS NON CURRENT CARRYING METAL PATH EXISTS, THEN REFER TO THE SECTION EXPLAINING HOW TO WIRE A DETACHED STRUCTURE WITH 3 OR MORE BRANCH CIRCUITS THAT IS 60, 100, or 200 AMP RATED, AND WITH AN EQUIPMENT GROUNDING CONDUCTOR RAN WITH THE FEEDERS BETWEEN BUILDINGS. If you have a metal water pipe ran underground, but that metal water pipe does not make contact between the two buildings, and if your metal water pipe, located at that detached structure, is in direct contact with earth, then that metal water pipe, and any other grounding method listed in Article 250-50 must be connected together to make that grounding electrode system. If that metal water pipe is installed in direct contact with the earth, but not installed connecting the two buildings, then you must use that metal water pipe in direct contact with earth as part of the grounding electrode system, but you must also supply a supplemental grounding electrode to back up that water pipe in case that metal water pipe is removed at a later date. Article 250-50-A-2 Remember, If any metal connection is existing between that main building and that detached garage then you must install that equipment grounding conductor between the two buildings with that feeder and as a part of that feeder installed between the two buildings. Article 250-32-B-1 & 2

Note # 5 – Minimum burial depth in a residential setting must be at least 18” deep unless in rigid or IMC threaded conduit these two conduits must be a minimum of 6” deep, if buried. Table 300-5.

Note # 6 - No part of this feeder from the breaker in the dwelling to the disconnect form in that detached garage may be rated in ampacity that is smaller than the overcurrent device {breaker or fuse} protecting that feeder in the dwelling’s panel. Article 210-19 & 215-2 & 220-3 & 220-10 & 240-3 & 240-6 If you install a 60 amp breaker 240 volt in the dwelling, then you may use a 6/3 without Ground UF cable from that dwelling’s panel to that garage disconnect. If you install a 100 amp breaker 240 volt in the dwelling, then you may use a 2 awg three wire URD cable from that dwelling’s panel to that garage disconnect. Article 338-3 If you install a 200 amp breaker 240 volt in the dwelling, then you may use a 2/0 awg three wire URD cable from that dwelling’s panel to that garage disconnect. Article 338-3 Approved wiring for underground can be but not limited to Type UF cable or URD cable if direct buried Article 338-3, or Type THWN, or THW, or TW if protected by a conduit. Article 310-13 You may install PVC schedule 40 when underground Article 347-2-G, or schedule 80 when exposed to physical damage Article 347-3-C. [SPECIAL NOTE; No metal conduit may be installed between the dwelling and detached garage, if you ran metal conduit you just made a non-current carrying metal path between the two buildings and you would have to refer to the drawing concerning wiring with an equipment grounding conductor instead of this drawing that is without an equipment grounding conductor.] Seal tight must not be used for burial using this drawing for the same metal path of the metal inside spiral as a part of that seal tight again you would have a non-current carrying metallic path between the two buildings. Type 2 non metallic seal tight may be used if listed for underground use and sunlight resistant. Article 351-23-3 & . 251-22-2 Type 2 non metallic seal tight is a seal tight that is as described {A smooth inner surface with integral reinforcement within the conduit wall, designated as Type LFNC-B}. ENT {electrical nonmetallic tubing} is not allowed to be used in direct sunlight or if buried Article 331-4. If you install the above conductors with a conduit protection then you must install two black wires and one white or gray wire in that conduit and the minimum size conductors are as follows; 60 amp copper = 6 awg or 4 awg aluminum Table 310-16 & 240-3-B. 100 amp copper = 4 awg or 2 awg aluminum Table 310-15-B-6. 100 amp copper = 2/0 awg or 4/0 awg aluminum Table 310-15-B-6.

NOW THERE IS HEAVY CONTROVERSY WHETHER YOU MAY USE TABLE 310-15-B-6 WHILE INSTALLING FEEDERS TO A DETACHED RESIDENTIAL GARAGE. YOU SHOULD CONFIRM WITH YOUR LOCAL ELECTRICAL INSPECTOR TO CONFIRM IF YOU MUST USE TABLE 310-16 OR TABLE 310-15-B-6 WHEN INSTALLING A FEEDER BETWEEN THE MAIN DWELLING AND THE DETACHED GARAGE. TABLE 310-16 CALLS FOR THE FOLLOWING SIZES; 60 amp copper = 6 awg or 4 awg aluminum Table 310-16 & 240-3-B. 100 amp copper = 3 awg or 1 awg aluminum Table 310-16. 200 amp copper = 3/0 awg or 4/0 awg aluminum Table 310-16 & 240-3-B.

DO NOT USE EMT {electrical metallic tubing} IN DIRECT CONTACT WITH EARTH. Article 331-4-A-5.

Note # 7 – Load side of disconnect serving the branch circuit wiring in the detached garage itself. This service panel installed inside your detached garage is where you start wiring the branch circuits serving the inside of your garage from, normally using nonmetallic sheathed cable. However there are many wiring styles allowed to wire the inside of this detached garage.

RECAP ON SOME ITEMS OF INTEREST

SPECIAL NOTE;

Article 240-21-B-5 allows a one time tap located on the outside of a structure, then feeding a second structure without any disconnect or overcurrent device required, until you reach the load side of that tapped feeder located at the second structure. This overcurrent device, and disconnect, may be installed either outside or at nearest point of entrance of that second structure. This feeder disconnect with the overcurrent device {fuse or breaker} installed on the load side of that tapped feeder is allowed to be installed as a tapped feeder, while using an unlimited length of that tap, in your wiring design. Check with your Electrical Inspector and your serving Utility Company, to ensure that you can use this unlimited tap rule. If they do not have special local rules forbidding this wiring design, then you can exchange your existing meter base to a larger meter base that is usually called a 325 amp meter base with double lugs on the load side in that meter base. These double lugs will allow one set of lugs in that meter base on the load side of the meter, to serve as your dwelling connection, and a second set of lugs in that meter base, on the load side of the meter, to serve as your detached garage connection.

If this unlimited tap rule is used, then no overcurrent device {breaker or fuse} or disconnect is required on the line side of that feeder. This over current device or disconnect is only required once you get to your detached structure on the load side of that feeder. That overcurrent device, and disconnect, or panel installed on the load side of that feeder must be sized equal to the ampacity of the feeder installed between that meter base, and that detached structure that the disconnect, and overcurrent device protects, from the load side of that feeder.

No disconnect, or overcurrent device, would be required on the line side of that garage feeder found between the garage, and the load side of your meter base.

Your garage load would not be carried through your dwelling’s panel load. That detached garage amperage load would only be found on the Utility company’s feeder, through the meter itself, and then the detached garage feeder, but not through your house affecting your house panel.

SPECIAL NOTE;

If you find a metallic path, such as a water pipe etc. connecting those two structures, then you must use the option found in 250-32-B-2, only, including an equipment grounding conductor with that feeder from the main dwelling to that detached structure whether overhead or underground feed to that detached structure.

A quadraplex, or triplex or duplex must have a steel core messenger cable to support the overhead service conductor that is running in the air between the two structures if more than 50’ long and smaller than # 8 copper or # 6 aluminum. Article 225-6 Most commonly a # 6 or larger duplex, triplex, or quadraplex is used for this overhead cable for loads 60 amps or smaller. 2 awg aluminum is allowed for 100 amp loads, and 2/0 aluminum is allowed for 200 amp loads normally. You may use the steel messenger cable as your neutral source if the grounding source is supplied new at the detached structure and a main panel is installed within the detached structure. This is true only if you do not install an equipment grounding conductor with the feeder from the dwelling, or as long as your grounding source is not using that bare messenger cable if the grounding is supplied from the dwelling and not at the detached structure as allowed in Article 250-32. If an equipment grounding conductors is installed with the over head feeder to the detached garage, then that bare messenger cable must be used as the equipment grounding conductor and the neutral must be insulated.

SPECIAL NOTE;

You must install a knob on the detached structure to attach the over head conductors in order to support the quadraplex, triplex, or duplex in the air. Article 225-12 The over head conductors are connected to the knob by what is called a triplex hanger.

SPECIAL NOTE;

You must not run quadraplex, triplex, or duplex feeders inside a structure.p

RESIDENTIAL BURIAL DEPTH REQUIREMENTS

If you opt to go underground, and if it is for residential use, and if you are going to direct bury the feeder, then you must be 18” deep Table 300-5 with conduit protection installed where subject to physical damage such as rocks while crossing a driveway. If you opt to go underground, and if you are installing the feeder in a rigid conduit, then you must be 6” deep if rigid conduit or IMC conduit is buried to protect the feeder the full length. If you are installing the feeder in a PVC conduit then you must be 18” deep, if PVC conduit is run protecting the feeder the full length. Table 300-5 If you are installing the feeder in a PVC conduit, and where buried under 4” of concrete then you must be 4” deep if PVC conduit is run protecting the feeder and the conduit is under at least 4” of concrete the full length. Table 300-5

COMMERCIAL BURIAL DEPTH REQUIREMENTS

If you opt to go underground and if it is for commercial use and if you are going to direct bury the feeder then you must be 24” deep with conduit protection where subject to damage such as rocks while crossing a driveway. Table 300-5

If you opt to go underground and if you are installing the feeder in a rigid conduit then you must be 6” deep if rigid conduit is buried to protect the feeder the full length., Table 300-5 If you are installing the feeder in a PVC conduit then you must be 18” deep if PVC conduit is run protecting the feeder the full length. Table 300-5 If you are installing the feeder in a PVC conduit and where buried under 4” of concrete then you must be 4” deep if PVC conduit is run protecting the feeder and the conduit is under at least 4” of concrete the full length. Table 300-5

SPECIAL NOTE;

The neutral must be insulated if buried underground.

A good rule of thumb is if you are using PVC as protection of a conductor you can use schedule 40 if not subject to physical damage {inside a building or above 6’} or schedule 80 PVC is subject to physical damage {outside a building or below 6’}

SPECIAL NOTE;

A service panel must be at the nearest point of entrance of the structure and may be located inside and not be required to be a weatherproof panel, or may be located outside but is required to be a weather proof panel.

PICTORIAL EXAMPLE OF AN UNLIMITED TAP RULE SUPPLYING POWER FROM HOUSE METER ONLY TO A GARAGE PANEL AND NOT APPLYING INCREASED LOAD THROUGH YOUR HOUSE PANEL.

Article 240-21-B-5

This unlimited tap rule does not require any disconnects or overcurrent devices except on the load side of that tapped feeder located either outside or at nearest point of entrance inside the detached garage. This unlimited tap rule allows you to omit any form of disconnect or overcurrent device located at your dwelling, as long as this tap rule is located outside and not inside your dwelling. There is no minimum or maximum reduction in size allowed or required considering the tapped feeder size compared to the feeder size supplying this tap.

This unlimited tap rule may normally be used with 3 or more circuits in a garage panel, 240 volt, 60 amp, 100 amp, 200 amp feeder circuit with underground conductors without an equipment grounding conductor ran with the feeder supplying the detached structure, and using what is called an unlimited tap rule connecting only inside the meter base installed on the outside of your dwelling, but not using the detached garage load through your dwelling’s main service rated panel. Using a common meter base yet not applying the load of the detached garage to your house panel. This wiring method only requires replacing your meter base with a larger amp rated meter base that is designed with double lugs. This wiring design would not affect the amp load of your house panel at all while installing power to your detached garage. Use this unlimited tap rule found in Article 240-21-B-5 only if it is allowed in your area by your local Utility Company and your local Electrical Inspector. The NEC allows this wiring design, yet you may have local rules forbidding this wiring style using that unlimited tap rule to be used in your area. Please confirm approval in your area before you finalize your wiring design.

UNLIMITED TAP RULE APPLIED Article 240-21-B-5

Note # 1 – When using the unlimited tap rule you, and if approved by your Electrical Inspector and your Utility Company, you may install the tapped feeder directly to the load side lugs located inside your double lug meter base. Then install that feeder to the detached structure and then install your main disconnect or overcurrent device either outside the detached structure or nearest point of entrance inside the detached structure. The main service rated panel and main overcurrent device {fuse or breaker} must be sized to protect the ampacity of that tapped feeder and located on the load side of that feeder. No overcurrent device {fuse or breaker} is required on the line side of that tapped feeder while installed outside any structure.

If the Utility Company forbids the use of this tap rule, then usually the authority of the Utility Company stops once the feeders leave the meter base on the load side of that meter base. Once you have the feeders beyond the meter then, again you would have to inquire with your Electrical Inspector whether he has a local law, or ordinance, forbidding the use of this unlimited tap rule allowed in the NEC. If you are not forbidden by a local law then you may install a weather proof junction box, using what is called a key tap, you may run a single feeder from your meter base using the 10’ tap rule then install a feeder from that key tap to the house panel and a second feeder using the unlimited tap rule to serve your detached structure in the same manner as described in the first paragraph of the Note 1. If you opt to use a key tap, then this key tap that I have in mind is built in a manner designed to be installed in a 6” X 6” weather proof duct. This key tap can be bought to accept almost any size of conductors, almost any number of conductors, and can tap up to 4 different type of conductors. This is true whether three phase with three hot conductors and one neutral conductor, or single phase with two hot conductors and one neutral conductor. This key tap looks like a unit built with three “U” shaped cavities with bakelite separations between the three or four “U”s. There are slide on caps with set screws in these caps to tighten down all conductors to be installed within this key tap. One word of warning is that you must not mix copper and aluminum in the same “U” channel of that key tap without an approved alloy style separator that is supplied with the Key tap.

This unlimited tapped conductor must be protected from physical damage when installed.

Remember that if you install an unlimited tap as described above you are essentially installing an non-fused conductor same as a Utility Company installs while installing the feeder to you dwelling. This tapped conductor, while using the unlimited tap conductor is not fused, and without a disconnect until you get to the end of that conductor. Be sure this wiring style is protected from any physical damage.

Note # 2 – When installing this panel using the unlimited tap rule in that detached garage please refer to the section wiring a service associated to these articles. This panel in this detached garage would be under the same rules as a new panel in a new structure. When using the unlimited tap rule the panel in the garage is a main service rated panel, which requires its own grounding electrode system, the neutrals and equipment grounding bars to be married together and the main service rated panel must have a main disconnect and main overcurrent device {fuse or breaker}. This wiring design while using the unlimited tap rule is not considered as two structures using a common service, as you have been reading before this unlimited tap pictured section.

Note # 3 – If you are allowed to tap into the Utility company’s meter base on the load side using double lugs, then one section of each lug {the two hot lugs and the neutral lug} will connect to the tapped feeder serving the main service rated panel in the garage, and the second part of each lug {the two hot lugs and the neutral lug} will connect that tapped feeder serving your dwelling’s main service rated panel.

Note # 4 – These two larger lugs are the Utility Company’s line side lugs that they connect to in an underground 325 amp rated meter base.

Note # 5 – This double lug is your neutral lug in an underground 325 amp rated meter base.

Note # 6 – This double lug is your Load side # 1 hot phase conductor that you must install the #1 hot phase conductor of each your dwelling’s panel and your detached garage panel to in an underground 325 amp rated meter base.

Note # 7 – This double lug is your Load side # 2 hot phase conductor that you must install the #2 hot phase conductor of each your dwelling’s panel and your detached garage panel to in an underground 325 amp rated meter base.

Note # 8 – Check with your Utility Company and your Electrical Inspector to confirm whether that Utility Company requires the grounding electrode conductor to be connected inside their meter base, or in the main dwelling’s service rated panel. {wire coming from your ground rod or other grounding electrodes listed in Article 250-50 to serve the structure’s grounding electrode system connected at its main connection} The NEC allows this grounding electrode conductor to be connected anywhere from the weather head at the Utility Company’s connections to your service entrance conductors to and including inside the main service rated panel. This rule varies as per locality. Please confirm the proper wiring style the Inspector and the Utility Company requires in your area.

This document is based on the 1999 national electrical code and is designed to give you an option, as a self-help, that should pass minimum code requirements. While extreme care has been implemented in the preparation of this self-help document, the author and/or providers of this document assumes no responsibility for errors or omissions, nor is any liability assumed from the use of the information, contained in this document, by the author and / or provider.

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