Rewiring a Garage


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Old 05-01-14, 03:43 PM
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Rewiring a Garage

Alright everyone, I am going to try and be as detailed here as I possibly can. I am rewiring my detached garage. The garage is roughly 40 feet from the house. The garage is currently wired, with 2 random breakers in my house breaker box. It only has 14 gauge wire going through to the garage, and since my house is old (it was built in the 50s) and the wiring color from the breaker to the garage is different I am certain I can't just run new wire through to the garage.

So the plan is I would like to dig out a new trench and lay down conduit, I have heard for outdoor use I need to use PVC 40, however I have no idea what kind of wire I should run. The garage currently has a fuse box with 2 circuits in it, I would like to put up a new breaker box with a 60amp service. I am planning on using an electric heater which requires a 220 line, and my air compressor which also requires a 220 line, then I would like to have a 120v/20amp circuit for the lights/outlets and then I would like to have a 120v/15amp circuit for the garage door opener itself, or would you guys say putting a garage door opener on its own circuit a little excessive? I am aiming to start doing the work in early June before the heat of a Chicago summer hits.

Is there anything else I am not thinking of here? It should just be run a certain amount of new wire from a 60amp breaker in my house to a new breaker box in the garage. I am a mechanic for a living and I do a lot of odd jobs out of my garage shop. I plan on having roughly 6 florescent lights, but those don't pull that heavy of a load. I am more concerned about the heater, and the compressor. I don't use a lot of power based tools, and I generally use pneumatic and I only have a 30 gallon compressor currently, which I may upgrade to a 60 gallon, so it runs pretty much nonstop. I hope I didn't ramble too much here and you guys can help me out, I do know an electrician who is willing to help me but his mother in law just died and I won't really see him for the next month or so. Any help would be greatly appreciated. I have a Northwest Electric fairly close to home so I should be able to get everything I need easily.

David
 
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Old 05-01-14, 04:36 PM
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Your panel sounds good for a start. You can search this forum for "sub panel" for many examples and diagrams to give you a basis to start.
 
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Old 05-01-14, 04:39 PM
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I have heard for outdoor use I need to use PVC 40, however I have no idea what kind of wire I should run.
You would run four THWN individual wires. Two #6 black (or one black and one red), one #6 white, and one #10 green From a 60 amp two pole breaker in your main panel. At least ¾" PVC conduit but 1" will make pulling easier. It need to be buried at least 18".

Simplest/cheapest for a subpanel will probably be a main breaker panel*. They come in kits that include the main breaker and a few branch circuit breakers. You need to buy and add a ground bar to it. A 100amp 12 space panel should give you enough room. (The 100amp main breaker serves as your required disconnect switch only not a breaker.) You will also need a ground rod at the subpanel. If the #6 is too small for the main breaker you will pigtail larger wire to them.

*A main lug panel could be used instead of a main breaker panel but if you have more than space for six circuits in the panel than a disconnect such as a back fed 60 amp breaker in the subpanel is required and a hod down used on the back fed breaker.
 
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Old 05-04-14, 09:24 AM
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Thank you so much guys! I need to start pricing stuff out and gathering supplies. Looks like I'll have to head to the electrical supplies store.
 
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Old 05-04-14, 12:04 PM
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This all might depend on how big of an electric heater you are thinking of installing. You might need to bump up the feeder to #4 or #3 copper. Are we talking about a couple 2000 watt heaters, or a 10KW heater?

The 100 amp sub panel should still work out for you though.
 
 

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