Garage Re-Wire


Old 09-13-00, 11:18 AM
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I re-wired my detached garage this spring and felt pretty confident that it was properly done. After reading responses to GreggM's posting, where references were made to a panel (load center) requirement, I'm not so sure now.

I'm aware of the minimum NEC requirement of one GFCI receptacle, and all I use out there are power tools. Since the largest anticipated load is my 1 HP table saw, which is rated at 16 FLA, I installed two 20 amp GFCI duplex receptacles above the workbench and hung the whole circuit off a 30 amp breaker in my house panel. I ran # 10 THHN in EMT to a JB inside the garage, (via a single 1/2" EMT at 8' above grade across a 3' span between house & garage)and distributed power to lighting and receptacles from there via # 12 THHN in EMT.

Also, I did not place a light switch by the service door. I know BOCA and NEC wrote code on this topic so people don't break their neck crossing a dark interior space, and I tackled this problem another way. Since my wife and kids usually leave the garage lights on all night I put the switch to the main overhead garage lights inside the house with a red indicator light on it. I installed a 9 watt PL fixture inside the service door, a stoop light and driveway spot all on a motion/photocell which of course times out automatically when nobody's around. I was trying to save energy and provide safety at the same time.

Please point out anything I may have done improperly.
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Old 09-13-00, 12:31 PM
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It sounds like you have the # 10 wires going
to the garage protected wth 30A breakers in
the house, which is okay, but nothing protecting the wiring down to 15 or 20A,
which is bad. You should install a small 4
circuit service panel where the #10 wire ends, and the #12 begins, or replace the 30A
breakers with 20A ones.
Old 09-13-00, 05:40 PM
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Are the lights in the garage on the same circuit as the GFCI's? I recommend at least (2) 20A receptacle circuits and 1 15A circuit for the lights. A garage door opener should be put on its own 15A or 20A circuit. It might be wise to install a 6 space subpanel instead of a 4 space. Use Square D QO series. If this is not available, GE or Cutler Hammer are the next best.
Install a 3-way switch inside the house and garage to control the exterior lights, and a single pole switch to control the interior lights.
Is the circuit breaker (existing 30A) a single pole or double pole? For a subpanel you will need a 120/240V 4-wire setup to supply the subpanel located in the garage.
Old 09-13-00, 07:16 PM
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I suspect that my reply is the one that alarmed you on your garage wiring. I tend to get to technical at times for laymen's terms. Sorry bout that!

You are correct about the minimum requiring only on receptacle in the garage gfi protected.

From what I understand you have only plug connected equipment. 16 amps is ok on a 20 amp circuit.

It sounds like the two twenty amp circuits are adequate for your needs. The demand that I was referring to was for connected loads. The plug in style appliances are considered convenience outlet style appliances and are used incidentally. They are not used in a demand load calculation. Just connected loads, permenant with a Romex connector style equipment.

As the previous replies questioned, I question a 30 amp breaker in the house serving two twenty amp circuits in the garage without a distribution panel. As the previous replies said 4 or 6 circuit panel would do fine.

I also question the solid emt between the buildings. The NEC requires flexibility between buildings for movement to be allowed between the two building. You left no room for natural movement of the two buildings. Something will have to give there possibly causing a hazard.
Your stoop light design should be adequate. Again I failed only this time I was not in enough detail. A light such as a dusk to dawn light that lights that stoop is allowed by the NEC as an exception to the stoop light on a switch.

Old 09-15-00, 06:52 AM
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Yes, WG, it was your reply. I'm glad now the topic came up, though. And thanks for the advice. I toiled to wire it initially, but I want it done right and I have no problem fussing to re-do it. Now that I think about it, a 30 amp breaker isn't going to protect any individual circuit out there. I suppose I could reduce the breaker to 20 amps, but I get a sense from your reply that the lighting (a couple fluorescent fixtures) and a (future) garage door opener should have separate protection from the receptacle circuit, and that this is the reasone a panel is recommended (or required?).

If I go with a sub-panel out there the only trouble I'll have is replacing the feeder from the house panel. I took 10/2wg from the house panel at the front of the house in the basement to the back of the house and up through 12" of concrete slab, then up and out to a JB in the canopy of my rear entrance stoop, and ran the EMT from there out to the garage. I'll have to replace all that with 10/3wg to bring 240 out to a new sub-panel in the garage, and that's gonna be time consuming! Oh well, live and learn. What I have now is 1,000 times safer than what the previous owner did (I won't elaborate here, you'll have nightmares!), but once I know something isn't right, it bugs me until I correct it.

As far as the solid EMT, can I use expansion couplings, or do I need flexible non-matalic type? I like the durability of the solid metallic, especially since the previous owner strung a piece of romex between the structures.

Thanks again for your help. (All of you.)


[This message has been edited by JuiceHead (edited September 15, 2000).]

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