Subpanel wiring dilemma


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Old 07-01-16, 07:44 AM
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Subpanel wiring dilemma

My attached garage is my shop. I would like to put in a 100 amp subpanel for my compressor and welders. Wiring the panel, outlets, and breakers isn't the issue. The issue is that my garage is on the opposite corner of the main panel, and my basement is finished with a drywall ceiling. Its going to be about a 80-90 foot run, either way. It would be easier to run conduit along the top of the foundation around to the garage, but I'm not sure what my options are for wire size when it comes to feeding the sub panel. I can fish it above the drywall if its going to be a lot cheaper.

Any thoughts on pros and cons, and wire size would be greatly appreciated.

Thanks in advance,

Matt
 
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Old 07-01-16, 08:48 AM
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Conduit would be a little more expensive, but it a perfectly valid option, and probably the method I would advise. In that case, you would use four individual conductors with THWN or XHHW insulation. If you choose to fish the cable through the basement ceiling you'll want SER -- however 100A cable will not fish all that easily, it's stiff and heavy.

On the conduit route, go with 1-1/4". The conductor size for 100A would be #1 aluminum or #3 copper.

On the cable route if you can live with 90A instead of 100A, the cable can be #2 aluminum which is a very common size. For the full 100A, go with #2 copper or #1/0 aluminum (you may only be able to find the larger #2/0).
 
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Old 07-01-16, 09:09 AM
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Definitely cheaper to pull cable instead of pipe but what a nightmare job that could turn into. That cable is not easy to work with.

I'd certainly opt for the conduit method.
 
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Old 07-01-16, 01:19 PM
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For 100A, SER cable does come in #1 Al or #3 Cu. It may have to be special ordered.
 
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Old 07-01-16, 03:04 PM
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The AL SER cable will be much cheaper than the copper. You may not even have the copper option.
 
 

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