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kbc 09-30-2012 07:48 AM

sub panel
i want a new 100 amp sub panel for an addition i was thinking of running three #1 coppers, a black, red, and white, and a #8 green ground, but i do not know what type of insulation thhn or what, and is 1- 1/4 emt suitable i would run the pipe inside

k_buz 09-30-2012 08:52 AM

How far away is this subpanel? By code, you would only need to run #3's CU to a 100A sub. If you are increasing the wiresize due to voltage drop, you must increase the equipment grounding conductor the same percentage.

1 1/4" will be fine, but if you are pulling a long distance, you may want to upsize to 1 1/2" to make the pull easier. You need a insulation type that is rated for wet locations, THWN is what you should be looking for, however, most THHN you buy is dual rated THHN/THWN.

k_buz 09-30-2012 08:52 AM

If this is a detached structure, don't forget the ground rods.

kbc 09-30-2012 08:56 AM

i thought #3 copper was rated for 85 amps and it is 60 feet away from main panel

k_buz 09-30-2012 08:58 AM

You thought wrong, at least according the NEC. #3 CU will be fine for your installation.

kbc 09-30-2012 08:59 AM

isnt #3 rated for 85 amps its 60 feet from main panel

k_buz 09-30-2012 09:10 AM

#3 THHN/THWN is rated for 100A

rjniles 09-30-2012 10:02 AM


Originally Posted by kbc (Post 1020377)
isnt #3 rated for 85 amps its 60 feet from main panel

You are confusing the ratings of a NM cable assembly with the ratings for individual THHN/THWN conductors.

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