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deere2440 03-01-2008 03:08 PM

New garage
Im building a new garage and need some electrical advice. First I'm wanting to eventually put a welder in it and want to know if 100 amp is good enough. Second the garage is about 40 feet from my meter and I want to bury the line, how deep should I bury it, what size wire to use, and what should I cover the wire with.

Any advise would be helpful

gregzoll 03-01-2008 03:20 PM

nap 03-01-2008 05:01 PM

100 amp would be adequate unless you are using an industrial sized welder and have a lot of additional loads.

wire size #3 copper (USE or THHW) or #1 aluminum ( USE or THHW)

if direct burial- 24"

rigid metal conduit- 6 "

PVC conduit- 18"

deere2440 03-01-2008 05:41 PM

Thanks for that input, it helps a lot!!!

nap 03-01-2008 06:23 PM

Do not forget you must have a main breaker panel or use a disconnect. You also will need a grounding electrode system and that now includes tying to the rebar in the foundation.

It helps to install a conduit through the forms when pouring the footer. Be sure to bring that up through the floor before you pour the floor.

Oh, and don't even bother with anything other than a 4 wire feed. A 3 wire may still be legal in your area (2005 code- ok, 2008 code-not) but it is simply less hassle to simply put the 4 wire in to start with.

deere2440 03-01-2008 07:19 PM

That is great info! I plan on a deep footer and havent planed on rebar in the foundation. The footer is going to be at least 30" deep and 1' wide all the way around the garage with the floor poured inside of that seperately. Plans are subject to change if needed. I am still learning how to do it the right way.

deere2440 03-01-2008 07:32 PM

Also, when I get to wiring the light/outlets should I use 12-2 with ground or 14-2 with ground?

handyman78 03-01-2008 07:35 PM

For residential I use 14-2wg for lights and 12-2wg for receptacles but in a garage I would probably just go with all 12-2.

deere2440 03-01-2008 07:41 PM


but in a garage I would probably just go with all 12-2
That is what I was thinking.

goose134 03-01-2008 07:42 PM

Brick garages are sweet.
Another thing to remember is that the largest size panel you can put in your garage is a function of the size of your main.

deere2440 03-01-2008 07:50 PM

I think that a 100 amp box is plenty for my garage. I bought a Square D Home line 100 amp box with main and 5 breakers today. I dont need it for awhile but it was on sale for 50 bucks. I like the square d's. I replaced my old Federal Pacific box in my house last year with a square d.

frenchelectrican 03-02-2008 01:50 AM

the other thing if you are on 08 code cycle you have everything in the garage to be GFCI'ed that including the lighting circuit and Garage door opener.

the 240 volts equiment is not need a GFCI unless the manufacter required for it. [ i doubt it but only one i know they do use the GFCI on 240 v unit is pressure washer that is the item i know of.]

Merci, Marc

deere2440 03-02-2008 01:28 PM


wire size #3 copper (USE or THHW) or #1 aluminum ( USE or THHW)

if direct burial- 24"

rigid metal conduit- 6 "

PVC conduit- 18"
What way should I go copper or aluminum? Should I use conduit, if so what size?

deere2440 03-03-2008 05:47 PM

Anyone have any preferences? Conduit is on sale this week and I am thinking plastic. Just because it sounds easier to work with. Copper or aluminum?

gregzoll 03-03-2008 07:24 PM

Check with local codes.

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