Wire Gauge


  #1  
Old 06-28-04, 05:01 PM
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Wire Gauge

I am looking to install a 100 amp sub panel in a shed/workshop. The distance from the service panel to the sub panel is roughly 30 feet and my question is what is the proper gauge of wire for a 100 amp project? I have both seen and been told by "pros" that #4 copper will do the trick. IF that is correct, what configuration is best suited for a short distance project with 15 or so feet below ground, a wife that wants a clean looking installation, and will require 5 90 degrees bends. I figure 1 1/2 inch grey PVC should allow for ease of wire pulling. Does THWN come in #4, because pulling one wire at a time might be much easier. Thanks for any assistance you can provide

Leslie
 
  #2  
Old 06-28-04, 05:15 PM
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You might consider using UF insulated wire and it will direct bury - That allows you to only use conduit where it comes out of the ground.
 
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Old 06-28-04, 06:08 PM
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Using #4 copper for a 100A subpanel is a very common error. Table 310.15(B)(6) of the NEC permits the use of #4 copper for the _main_ feed to a dwelling.

At a minimum you will need #3 copper, and this only if you are certain to use 75C conductors and terminations. Otherwise you will need to use #2 copper.

You are permitted a maximum of 360 degrees of bend between 'pull points', so your 5 90 degree bends will require that at least some of your bends be some sort of conduit body so that you can do an intermediate pull of the conductors.

Do not pull one conductor at a time; pull them all at once. Otherwise one wire rubbing against the other could damage the insulation.

Make sure to use wire-pulling lubricant.

THHN (dual rated to THWN) or XHHW should be available as individual #3 or #2 conductors.

1.5" conduit is more than large enough even for the #2 Cu conductors.

-Jon
 
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Old 06-28-04, 07:05 PM
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Wire Gauge

Thanks for the quick response and useful information, just wish our electrical inspector was as helpful.

Thanks

Leslie
 
 

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