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8/3wg romex #172030
12/11/07 09:57 AM
12/11/07 09:57 AM
sparkync  Offline OP
Joined: Oct 2002
Posts: 830
According to the wire table 310-16 ( 99 Code Book, I don't have my new book with me) # 8 wire is good for 50 amps in the 75 degree column, and I know this is good only if the terminals are rated 75 degrees, which they are. Does
8/3 with ground romex qualify for this rating also? I had an inspector tell me once that it didn't, but I can't find where he would have got that from unless it was in an old code at the time. Thanks, Steve...

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Re: 8/3wg romex [Re: sparkync] #172031
12/11/07 10:30 AM
12/11/07 10:30 AM
earlydean  Offline
Joined: Dec 2003
Posts: 751
Griswold, CT, USA
He is maybe refering to 334.80, which limits the ampacity of NM cables to that of the 60 degree column.

Re: 8/3wg romex [Re: earlydean] #172034
12/11/07 12:37 PM
12/11/07 12:37 PM
gfretwell  Offline

Joined: Jul 2004
Posts: 9,187
Yup that is what he is talking about and you can't get away with the "round up" trick you can with #6 since 40 is a standard breaker size. Even if you decide to go for SE/SER you still can't use the 75c column because of 338.10(B)(4)

Greg Fretwell
Re: 8/3wg romex [Re: gfretwell] #172072
12/11/07 11:45 PM
12/11/07 11:45 PM
KJay  Offline
Joined: Nov 2007
Posts: 763
Hi Greg,
I could be wrong, but I thought 338.10(B)4 excluded 334.80 Ampacity. confused

Re: 8/3wg romex [Re: KJay] #172079
12/12/07 01:36 AM
12/12/07 01:36 AM
gfretwell  Offline

Joined: Jul 2004
Posts: 9,187
You are right. I should try to read a little better before I speak. My original thought was that it was OK, then I looked it up. wink

Greg Fretwell


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