Well, we finally closed and moved in to our new home. I called around and the electrical contractors in my neck of the woods are ridiculously expensive. So Off to Lowes I went. I bought a Eaton 100 amp panel with a 100 amp breaker + 5-20 amp breakers for like $60.00. 250 feet of 12/2 wire, 20 amp outlets, covers, wire staples etc.. I'm going to get my permit tomorrow to install this myself. I have two spaces in my main breaker panel in the house which is a good thing.My trouble is this: It's just that after doing an exhaustive search on youtube and the internet, I cannot for the life of me find out what cable I need to run from my main breaker in the house underground in schedule 40 pipe to my garage. Yes, I know what I'm doing, just wanted an electrician to do it for me. I'm old and lazy,but the prices for electricians were out of this world.Any help would be greatly appreciated.

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    I think you should pick up a copy of the NEC. Not knowing what to put in the conduit is at odds with "knowing what I'm doing". – whatsisname Aug 26 '15 at 4:29

Have you tried searching the site? The panel feeder size question has been answered many times. Here's one such example.

Is you're planning to pull a cable, you'll use 3-3-3-5 USE cable with copper conductors (1-1-1-3 for aluminum). If you're pulling individual wires, you'll want four 3 AWG THWN wires (hot, hot, neutral, ground)(black, red, white, green) (1 AWG for aluminum). If the run is going to be really long, you'll want to calculate the voltage drop and adjust the conductor size accordingly.

If you use the 3-3-3-5 USE cable, you don't need conduit. If you want to install it in conduit, you'll need 1 1/4" schedule 40 PVC. If you use individual THWN wires, you'll also use 1 1/4" schedule 40 PVC.

You'll have to keep the grounded (neutral), and grounding bars separate in the secondary panel.

You'll have to install a grounding electrode system at the garage, and bond the equipment and grounding conductor to it.

NOTES: This is a very broad, and generalized overview, which lacks specific details for your particular situation. You may need the advice of a licensed Electrician, to provide a more detailed plan based on the actual job site.


For powering a sub-panel through a conduit I'd use any stranded THHN cable. Code states you need to run 3 wires and a ground. Remember at the sub-panel the neutral and ground busses are separated.

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