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Home > Home Wiring USA Archive: NEC 1999 > Main Dwelling Design and Options > Common Wiring Methods Used Concerning Wiring an Attached Garage (NEC 1999)

Common Wiring Methods Used Concerning Wiring an Attached Garage (NEC 1999)

By Warren Goodrich
Common Wiring Methods Used Concerning Wiring an Attached Garage (NEC 1999)


If you are attempting to wire a garage, that is attached to a dwelling, the absolute minimum wiring that should meet the minimum safety standards set forth in the NEC would be as follows:

The minimum wiring required in an attached garage would be switches at the service door to control a light both inside 210-70-A-2 and a light serving the stoop outside the garage service door 210-70-A-2. Vehicular doors of a garage are exempt from any lighting requirements 210-70-A-2.

A GFCI protected receptacle somewhere inside the attached garage is also required 210-52-G. The light 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, { two switches controlling the same lighting } to serve as the required second switch at the garage / dwelling entrance. You may decide on an option to install two lights inside the garage, one controlled at the service door and the second light controlled at the garage / dwelling entrance. The first option { using a three way switch serving the same light or more lights 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 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 GFI protected. 210-8-A

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 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 serving that appliance. 210-8-A-Exc.1 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 can still not be GFCI protected.210-8-A-Exc.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, then the GFCI protection is not required, in this particular scenario as long as it is located behind one of the appliances. 210-8-A-Exc.2 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 GFI protection is not required.210-8-A-Exc.1 If you use a normal lighting fixture that is constructed without a receptacle mounted on the fixture, then the GFCI protection is not require the GFCI protection. A lighting fixture with a receptacle mounted on the fixture must be GFCI protected, if readily accessible as described above.210-8-A

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, not residential garages.511-3 Residential garages are exempt [mute] from this requirement. Be careful of this rule. A detached garage may be declared by the “authority having jurisdiction” as a commercial garage even if located in your back yard. 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 as pertaining to the Plan Commission’s zoning rules.

Outside receptacles, basement receptacles, and garage receptacles can be run on the same circuits, and can be protected by the same GFCI device. 210-8 Kitchen 210-52-B-2 and bathroom 210-11-3 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.210-52-B-2 and 210-11-3

There are two forms of GFCI protective devices. You may use a receptacle style GFCI protective device, or a breaker style GFI 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 compared to the breaker style GFCI protective device. 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.

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 table 220-3-b 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 it is a 20 amp conductor, you are using to wire the dwelling, then you would take the answer of the square footage times 3 Va. and divide that answer by the 2400 Va. for a 20 amp conductor. That would tell you the total number of 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 branch circuits. Table 210-3 and 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.

If you are utilizing motors or other such equipment 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%. 210-23

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. Code mute Please keep in mind that the Code requires a form of disconnect on all equipment. 430-102-B There is an exception allowing the breaker of a panel to serve as a disconnect if that breaker is within sight.430-102-B and exception Upon research, you should find the definition of “in sight” is if you can see breaker and if it is within 50’ of the breaker. 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}.430-110-F Code mute concerning GFI protection of the above described receptacles. 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.

Type Non-metallic sheathed cable [romex] is an accepted wiring practice if not subject to physical damage. 336-4 Most inspectors will consider type NM cable [romex] as not subject to physical damage if ran within a stud space, whether drywalled 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. 310-8-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.300-4-B-1

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.

Tables 310-13

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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