100 amp sub panel. what do i need to do for wire?

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Old 12-01-15, 07:03 AM
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100 amp sub panel. what do i need to do for wire?

i have 200 amp main in basement. what i'd like to do is just drill holes through my joists and out into the garage to 100 amp sub in attached garage. so i guess what i am wondering is what wire can i use for this? i'd rather not run it in conduit if i don't have too. it will be a finished basement.
 
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Old 12-01-15, 10:57 AM
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Why do you think you need a full 100 amps in the garage? Is the subpanel rated at 100 amps? I wouldn't install more than a 60 amp circuit with 6-3 NM-B cable to the subpanel fed from a 60 amp 2 pole breaker in the basement main panel and that would be gobs of power for any garage.
 
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Old 12-01-15, 11:11 AM
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i more then likely don't need 100 amps. i have the 100 amp panel i'd like to wire it for 100 amps. i have a few things out there that will draw some power. it will also feed my cloths dryer. your idea for the 60 amp circuit would more then likely work. i'm just wondering how much more $ and trouble the 100 amp would be. so i just need to know if there is a wire i can use inside in this application.
 
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Old 12-01-15, 11:24 AM
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For a full 100 amps I would install 1 1/4" conduit and use 3 - #3 copper conductors and 1 - #8 ground, but you wanted to run cable. My first cable choice would be 2-3 NM-B cable, if you can find it or #1 aluminum SER cable. These cables would be pretty difficult to pull through holes bored in the joists.
 
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Old 12-01-15, 11:32 AM
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thanks, i want to finish the basement and don't want to see the conduit on the bottom of the joists.
unless you're saying you'd put the conduit in the joists. that seems like it'd be harder then pilling wire, and i'm not even sure you can do that? am i missing something there?
 
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Old 12-01-15, 11:40 AM
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I agree with Joe, you should definitely consider running a 60A feeder. Wire is pretty expensive and the larger gauges are even more difficult to run. A 60A garage subpanel is likely more than enough for a well-furnished one or two-person shop.

I installed a 100A subpanel in a basement and dealing with the Al feeder cable was like wrestling a python (or at least what I'd imagine wrestling a python would be like). There was no way that cable was going through any bored holes, it was hard enough to just get it attached to the bottom of the joists. Copper would of course be a bit easier and downgrading to 6ga wire.
 
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Old 12-01-15, 11:52 AM
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If you have a helper to unroll the cable correctly and if you use hole saws or a decent size forstner bit to bore the joists, you can pull SER cable through framing. You can't make any tight corners -- at least a 1' radius or so will be required. The #1 aluminum SER for 100A will probably be about the same cost as #6 copper for 60A, but it will be more work to install.
 
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Old 12-01-15, 12:18 PM
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so my choices are 1-3 alum ser cable with a 2 awg ground, or some kind of 2-3 copper nm-b with 8 awg ground. now i will see what i can find. thanks again guys

troy
 
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Old 12-01-15, 03:19 PM
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I suppose we all assumed this was an attached garage. If it is detached, please post back as the answers are different.
 
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Old 12-01-15, 03:42 PM
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and out into the garage to 100 amp sub in attached garage....it will also feed my cloths dryer
Since it is attached it wouldn't cost much more and be easier to run one 10-3 for the dryer and a 8-3 or 6-3 for the subpanel. 8-3 on a 40 amp breaker may be enough unless Santa is bringing you a plasma welder or big honking air compressor.
 
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Old 12-02-15, 06:14 AM
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attached,

i am ok with the added cost for the 100 amp breaker. alum looks like its not really that spendy. i should be able to get a few people to help my wrestle it through...
 
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