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Common Wiring Methods Used Concerning Wiring an Attached Garage (NEC 2002)

By Warren Goodrich
Common Wiring Methods Used Concerning Wiring an Attached Garage (NEC 2002)

The following article talks about common wiring methods and procedures used concerning wiring an attached garage or a new dwelling. Based on the 2002 edition of the National Electrical Code.

If you are attempting to wire a garage that is attached to a dwelling the absolute minimum wiring that is required in order to be within the minimum safety standards set forth in the NEC would be as follows.

The minimum wiring required in an attached garage would require at least one wall mounted switch designed to control an area luminaireinside the garage. NEC Article 210.70.A.2.A A wall mounted switch installed at each service door designed to control a luminaire serving the stoop outside the garage service door, or one switch at one of the service doors to control all the luminaire required to be installed outside each service door. NEC Article 210.70.A.2.BVehicular doors of a garage are exempt from any lighting requirements NEC Article 210.70.A.2.B. A 15 or 20 amp rated GFCI protected receptacle shall be installed somewhere at a readily accessible location inside the attached garage in addition to any laundry receptacle circuits, if with laundry in that garage, is also required NEC Article 210.52.G. The luminaire installed to serve the inside of the garage and that is controlled at the service door can be wired as a three way switch system if so desired, .{two switches controlling the same luminaire} to serve as the required second switch at the attached garage’s dwelling entrance.

You may also decide on an option to install two luminaire controlled separately inside the garage, one controlled at the service door and the second luminaire controlled at the garage’s dwelling entrance. The first option {using a three way switch serving the same luminaire or more luminaire on the same switch system} is the most common choice to reduce confusion in switching systems and a possible reduction in wiring cost.

If you desire to provide more electrical wiring in your attached garage, 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 GFI protected.NEC Article 210.8.A

Exceptions

The following exceptions can apply concerning your GFI protection of receptacles in an attached garage, if these attached garage receptacles meet the requirements of these exceptions. If a duplex receptacle is located behind a large appliance such as a refrigerator, freezer, washer, dryer etc., making the duplex receptacle “not to be readily accessible”, and if this duplex receptacle is located behind the large appliance, then the GFI protection is not required to protect that non-readily accessible receptacle that is serving that appliance and located behind that appliance. NEC Article 210.8.A.Exception.1 If a receptacle serving a large appliance is located so that it is not located behind the large appliances in a manner so that it“is readily accessible” then that receptacle that is serving that appliance but is not installed behind that appliance must be a single receptacle and not a duplex receptacle. If this receptacle serving that appliance is a single receptacle and not a duplex receptacle then this single receptacle can still be without GFCI protection. NEC Article 210.8.A..2.Exception.2 If you have a washer and a gas dryer, and the duplex 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 serves both the washer or dryer, and this duplex receptacle serving both appliances is locate between these two large appliances then the GFCI protection is not required, in this particular scenario as long as it is installed between the large appliances or is installed behind one of the large appliances. NEC Article 210.8.A.2.Exception.2If you have receptacles that are installed so that they are 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 to serve that receptacle. NEC Article 210.8.A.2.Exception.1

If you use a normal luminaire that is constructed without a receptacle mounted on that luminaire or built into that luminaire, then the GFCI protection is not required. A luminaire with a receptacle mounted on the luminaire or built into that luminaire must be GFCI protected, if readily accessible as described above. NEC Article 210.8.A.2

Residential Garages

There is a statement in the NEC that says you must not have electrical wiring, or open flame appliances within 18”of the floor. This NEC requirement applies only to commercial garages. This 18”requirement does not apply to any residential garages. NEC Article 511 This article applies only to commercial garages, and does not apply to residential garages. Residential garages are exempt [mute] from this requirement. Be careful of this rule. A detached garage may be declared by the “authority having jurisdiction which is normally your electrical inspector” as a commercial garage, even if this garage located in your back yard. This ruling, as to whether a detached garage is a commercial or a residential garage, would normally depend on the design, size of the structure, or the apparent use of the structure as pertaining to the Plan Commission’s zoning rules. However it is within the “authority having jurisdiction’s” powers of ruling to declare a garage located in a residential setting to be a commercial garage in design.

Outside receptacles, basement receptacles, and garage receptacles can be run on the same circuits whether 15 amp rated 14 awg branch circuit conductors or 20 amp rated on 12 awg branch circuit conductors, and can be protected by the same GFCI device again not mattering whether the GFCI receptacle if used is a 15 amp rated GFCI receptacle on a 15 or 20 amp rated branch circuit or 20 amp rated GFCI receptacle on a 20 amp rated branch circuit. NEC Article 210.8 and Article 210.21.B.2 Kitchen NEC Article 210-52.B.2 and Article 210.11.C.1 and bathroom NEC Article 210.11.C.3 receptacles must be dedicated as their own circuits, therefore kitchen and bathroom receptacles must not be wired on the same circuits as the garage, basement or outside receptacle circuits regardless the fact that they are required to be installed with GFCI protection.

GFCI Protective Devices

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. A breaker style GFCI protective device is designed to be both the overcurrent device and the GFCI protective device incorporated as one unit and installed in the distribution panel. The receptacle style GFCI protective device is designed to be both the first duplex receptacle and the GFCI protective device incorporated as one unit and installed as the first receptacle box 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 on the same circuit on the load side of that GFCI coming from that same GFCI protective device located as the first receptacle on that 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 as one price to compare then compared to the breaker style GFCI protective device as the second price to compare in your comparison prices. I suspect you will find the GFCI receptacle combined with a normal breaker to be much cheaper than single the GFCI breaker. Both devices will do the job and should meet the NEC minimum requirements. Its your choice.

Non-Living versus Living Areas

Please do not confuse non-living areas, such as a commercial area, with a living area inside of a dwelling such as a living or bedrooms basements garages. The general use receptacles associated to a dwelling unit would be calculated by multiplying the square footage of the dwelling {minus the garage or unfinished basement}times 3 volt amps per square foot found in NEC Table 220-3-A of the NEC and then dividing that by 100% of the ampacity of the conductor that you are wiring. In order to find the Va. of a 20 amp conductor you would multiply the amps times the voltage this would be the Va. capacity of that conductor or 15 amp conductor times the voltage on a 15 amp circuit. If you are using 20 amp rated branch circuit conductors, to wire the dwelling, then you would take the answer of the square footage times 3 Va. and divide that answer by the 2,400 Volt amps for a 20 amp rated conductor. That would tell you the total number of 20 amp rated general lighting branch circuits required for the living areas of your dwelling. You must install all of the general use receptacles, found in the living areas of the dwelling, equally on that number of 20 amp general lighting branch circuits using 12 awg branch circuit conductors. NEC Article 210.3.A and NEC Article 220.3.B.10 and NEC Article 210.11.BIf you are using 14 amp rated branch circuit conductors, to wire the dwelling, then you would take the answer of the square footage times 3 Va. and divide that answer by the 1,800 Volt amps for a 15 amp rated conductor. That would tell you the total number of 15 amp rated general lighting branch circuits required for the living areas of your dwelling. You must install all of the general use receptacles, found in the living areas of the dwelling, equally on that number of 15 amp general lighting branch circuits using 14 awg branch circuit conductors. NEC Article 210.3.A and NEC Article 220.3.B.10 and NEC Article 210.11.B

Receptacles found in commercial setting such as repair garages, etc. that are not associated to dwellings and are used as a commercial basis would be considered as for continuous use therefore requiring the use of the 180 Va. per receptacle rule. You are allowed to install either 15 amp rated receptacle branch circuits or 20 amp rated receptacle branch circuits in a Commercial garage. Either must be calculated by using the 180 volt amps per receptacle to find the number of receptacles allowed on the circuit whether 15 amp or 20 amp rated in commercial garages. [Just for your information]. NEC Article 210.3.B.9

If you are utilizing motors or other such equipment as a single dedicated branch circuit in your dwelling’s attached garage, then you would have to calculate the load on that circuit created by all motors or other equipment 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%. NEC Article 210.23.A.1

Receptacles

If you are using a circuit that is rated 220 volts or if you are using special utilization equipment requiring specialty plugs, or a circuit that is hard wired without a receptacle, then no GFCI protection is required. “NEC Code mute” Please keep in mind that the Code requires a form of disconnect on all equipment. NEC Article 430.102.B There is an exception allowing the breaker of a panel to serve as a disconnect if that breaker is within sight. NEC Article 430.102.B Upon research, you should find the definition of “in sight” is if you can see breaker and if it is within 50’from the breaker. NEC Article 100 definitions A receptacle may serve as a form of disconnect, {if it is not a convenience style receptacle, example would be a twist lock receptacle or a 220 volt style receptacle it may not be GFI protected} {or if it is a convenience style receptacle then it must be GFI protected}. NEC Article 210-8 and 430.109.FCode mute concerning GFI protection of the above described receptacles other than in an attached garage, detached garage, bathroom, outside receptacles, and basements. A non-fused disconnect may serve as a disconnect if the circuit is protected at the beginning of the circuit by an overcurrent device such as a fuse or breaker. A second fuse or breaker is not required on a circuit, only a form of disconnect is required.

Sheathed Cable

Type Non-metallic sheathed cable [Romex] is an accepted wiring practice if not subject to physical damage. NEC Article 336.10 Most inspectors will consider type NM cable [Romex] as not subject to physical damage if ran within a stud space, whether dry-walled or not. Most inspectors will react to a type NM cable that is ran on the surface of the studs or posts. The inspector probably will consider this wiring method to be exposed to physical damage. You might lean a ladder or similar item against the stud or post and be laying against the cable. This would often be considered to be exposed to physical damage. Any wiring exposed to the outside elements would be required to be approved for sunlight resistance and approved for a wet location. NEC Article 336.12.A.10.D If you are installing a non-metallic sheathed cable through a metal siding or wall covering then you must us 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. NEC Article 334.15.B

Buried Wiring

If any wiring is direct buried, then the letter U must be labeled on the wire approving the use as direct buried. If any wiring is buried within a conduit, then the letter W must be labeled on the wire approving the use as a wet location. NEC Table 310.13

This document is based on the 2002 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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