Electrical to Detached Garage

Old 04-19-18, 09:23 AM
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Electrical to Detached Garage

I have a relative that wishes to expand the existing electrical circuit to his detached garage. Its been several months since I have seen it, so I need to go verify what he has, but had a question ahead of time. From my memory several months ago, I believe he has one 12/2 cable (w/ ground) coming from the main panel at the house using a 20A circuit breaker. I am not sure if this is direct burial or in conduit.

I seem to remember comments that current code will only allow 1 electrical circuit to be ran to a detached structure such as this garage. If you wish to have 2 or more circuits or higher capacities, then a subpanel is required. Of course I know I can place a new subpanel in the garage and would follow the proper codes accordingly.

However his needs are small, as he does not expect to have a full fledged workshop in the garage. But he would like a 2nd circuit ran to add a few outlets for convenience and possibly separate outlets from lights & garage door opener. Can I run another 12/2 cable, thus making 2 separate circuits in the garage? If I can, I will then investigate my best way getting it there.

If I cannot, then I may just install a new exterior outlet on the corner of the house. It's only 20 - 30' from the house to the garage. Then tell him to run an extension cord if he wishes to run multiple tools at the same time, or a tool that has a heavy draw.
Thanks I appreciate your help. Mike
Old 04-19-18, 09:58 AM
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You're right on the single circuit per outbuilding. Code would not allow two active circuits to the garage. A midway point between the single circuit and subpanel is a multiwire branch circuit MWBC. You could abandon the old run to the garage and install a new 12-3/g (black, red, white, bare) UF-B from a double-pole 20A breaker. It behaves just like two 20A circuits, but from the code point of view it is considered one circuit.
Old 04-19-18, 10:30 AM
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Or i wonder if a new 12/2 wg uf to feed outlets outside the garage? Does it count if not inside?
Old 04-19-18, 10:40 AM
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Ben's suggestion of a Multi-Wire Branch Circuit (MWBC) is probably your best bet. A 12/3 cable will give you two 20A circuits at the garage to do with what you need.

40A is sufficient for just about any one-man shop operation (barring any larger tools; welder, large table saw; etc). How many times would you use a drill, saw, shop vac, and garage door opener all at the same time.

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