Wire type/size for 80 amp sub panel

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  #1  
Old 07-02-12, 07:15 PM
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Wire type/size for 80 amp sub panel

I am running a 80 amp sub panel to a attached garage off a 200amp service, approx length will be 40 ft . House is a concrete slab so main box in on the first floor, I plan on running it above to a crawl space above which allows plenty of room to run it.

I am planning to go with a #4/3 copper but would like to hear any other opinions.
 
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Old 07-02-12, 07:30 PM
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I believe that 4-3 with ground is only good for 70 amps.
You will have to step up your conductor to a #3 Copper. If you go aluminum it will be cheaper, but you would have to go larger. You may be able to get away with a #2 Al SE cable, but you would have to limit your load to 75 amps.
 

Last edited by SeaOn; 07-02-12 at 07:50 PM. Reason: Added Alum
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Old 07-02-12, 08:41 PM
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I plan on running it above to a crawl space above
Just a note houses on slabs don't have crawl spaces. I know you mean attic but it is just one of those things that bug me. A crawl space is between the floor and ground. When in the heck did someone decide an attic is a crawl space? Okay back to your regularly scheduled program.
 
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Old 07-03-12, 03:51 AM
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4/3 NM cable is only good for 70 amps. #4 THHN in conduit is good for 90 amps.
 
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