Wiring a Garage

Old 10-10-03, 10:16 AM
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Wiring a Garage

I read many great posts here but none are exactly what I need.

I have a 200A panel which is full. I added the last few breakers for various projects over the 14 years in the house and I'm sure many of those are not used to their full potential.

I now want to wire my garage. I will be installing two garage door openers, probably four overhead double flourescent lights, and lots of outlets for convenience. A work bench with a small grinder but no major machinery. I do have a table saw and compressor that are 110V but draw pretty good current. I think I would prefer to have a sub-panel in the garage so I will have room for expansion. The garage is detached with no metal connections to the house but I anticipate putting a phone out there.

Should I put a smaller sub-panel beside the 200A (because its full) just for the garage or would I be better off to consolidate a few circuits to open up a slot? I'd like 220V out there (you never know).

What is typically a good size panel for a garage as described - 50A - 100A?

I know there is a diffent approach when there is a metal connection between the two buildings. My guess is I need three wire cable plus ground - not sure of the gauge. Do I need to ground with electrode(s).

Please point me in the right direction. Sorry this is so long!
Old 10-10-03, 10:47 AM
Join Date: Sep 2003
Location: Central New York State
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Several suggestions.

Depending on the breaker panel, you can sometimes combine two separate breakers into a single mini breaker. A min breaker contains two separate connectors and two separate switches. Each half is an independent breaker. Depending on the number of breakers already in the panel, you can do this to free up enough circuits for the entire garage, or to just free up enough space to install a 220 breaker to feed the garage.

A word of caution. Do not simply combine existing circuits on an existing breaker, unless the breaker is specifically designed to have more than one wire connected to it.

You can place the new panel either in the garage or right next to the existing panel. Placing the panel in the agrage means you have less distance to walk if you trip a circuit. Placing the panel next to the existing panel means you have less distance to run your four conducter cable to feed the sub panel.

100 amps is a lotof power for what you indicate will be in the garage. The bigger question is, what devices will be run at the same time? It is ulikely that you will be running the saw, the grinder and the compressor at exactly the same time, but you may be running the grinder and the compressor or the saw and the compressor at the same time.

Remember that the outlets in the garage must be GFCI ptotected, either at the outlet or at the breaker.
Old 10-10-03, 11:54 AM
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The panel is GE. I'll try to find if mini-breakers are available for it. That way I can have the sub-panel in the garage. That seems to be the best solution for me.

If I run into problems once I start the job I'll reply to this post>

Thanks again.
Old 10-10-03, 11:59 PM
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yes, put grounding rod @ gar
Old 10-13-03, 12:59 PM
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Ok! Grounding rod at the garage panel (connected to the ground bus in the panel?)

And what about bonding vs not? I will have metal connecting the two buildings via a telephone line and I am guessing that makes the difference. And what gets bonded to what - neutral to ground?

Also, I suspect I need a 220 breaker in the main panel and another of the same size in the sub-panel acting as a disconnect for it. Is this the proper configuration?

The thread above states to run "four conducter cable to feed the sub panel". That's four including the bare ground wire or is there a special cable to feed a subpanel with four insulated wires? (I never think of the bare ground wire as a conducting wire)

What is the proper cable size for a 100A sub panel?

I'm starting to realize this isn't as simple as adding a new circuit for my basement workshop with 12/2 and a GFCI breaker.

Please be as technical as you want. I'm not stupid, just not informed. I'll catch on quick.

By the way, great site and forum.

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