wiring residential detached garage

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howardrichman

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I'll be wiring a detached garage w/unfinished walls, used as a shop and storage shed, no cars. and as far as I know in attached garage, I'd plan on running romex as I'd wire any other room in the house. There will be a sub panel, lighting and receptacle outlets. Are there any additional provisions to be aware of, other than protection from physical damage?

HR...
 
The subpanel will require connection to a GES, could be 2 ground rods if the structure is existing or has no 1/2" or larger rebar in the footing.
 
I have seen many garage areas wired with exposed nm cable that were drilled across the joist. Heck, I had done some myself many moons ago. Art. 334.15 gives you guidance

334.15 Exposed Work. In exposed work, except as provided in 300.11(A), cable shall be installed as specified in 334.15(A) through (C).


(A) To Follow Surface. Cable shall closely follow the surface of the building finish or of running boards.

(B) Protection from Physical Damage. Cable shall be protected from physical damage where necessary by rigid metal conduit, intermediate metal conduit, electrical metallic tubing, Schedule 80 PVC conduit, Type RTRC marked with the suffix -XW, or other approved means. Where passing through a floor, the cable shall be enclosed in rigid metal conduit, intermediate metal conduit, electrical metallic tubing, Schedule 80 PVC conduit, Type RTRC marked with the suffix -XW, or other approved means extending at
least 150 mm (6 in.) above the floor.


Type NMC cable installed in shallow chases or grooves in masonry, concrete, or adobe shall be protected in accordance with the requirements in 300.4(F) and covered with plaster, adobe, or similar finish.
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Another requirement is you will probably need a main breaker in the panel. I usually use a main lug panel and install a breaker and back wire it-- back fed breaker (art. 408.36(D)). You will need a hold down kit for the breaker. Not all panel can be done this way so make sure it can use a hold down kit.

You may also be able to use the 6 breaker rule and not have a main breaker depending on the code cycle. IMO, for an extra $15 the main breaker is a better install.
 
+1 on the panel with a main. The panel and main CB could be 100 amp even if the feeder is of a lower ampacity.
 
Dennis Alwon said:
I have seen many garage areas wired with exposed nm cable that were drilled across the joist. Heck, I had done some myself many moons ago. Art. 334.15 gives you guidance
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Depending on what code cycle the OP is under running exposed NM in a detached garage is a violation. (15 min wall finish required)

If I was under that code cycle I would use MC however my own garage is NM. :cool:
 
iwire said:
Depending on what code cycle the OP is under running exposed NM in a detached garage is a violation. (15 min wall finish required)

If I was under that code cycle I would use MC however my own garage is NM. :cool:
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That is true however I believe most inspectors allow it as the 2014 does. 8f the building is associated with a residence they generally use the dwelling rules. I assume that is done in many other areas. Something to ask the ahj about.:thumbsup:
 
Thanks for replies; I will use a panel w/ main and 2 ground rods. I'll either use romex of MC. I guess it depends what it will be used for. if working on equipment w/ gas/oils, use MC, used for just storage, Romex.

HR...
 
The panel does not have to come with a main breaker, you can back feed a breaker and that will be your main disconnect. However, that breaker has to be tied down.

Don't forget all of your receptacles have to be GFCI protected and GFCI device be accessible. There may be some energy code regarding the lighting. Also without checking the NEC book, you may need a light by the man door entry of the garage.
 
norcal said:
MC & NM cable both have the same requirements for protection from physical damage.
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Again, that depends on which code cycle he is under. In some code cycles NM cannot be run exposed at all in a detached garage. While MC can always be run exposed.
 
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