Wire Derating - 30 Amps


Old 03-17-14, 06:17 AM
Thread Starter
Join Date: Jul 2009
Location: NYC
Posts: 302
Received 0 Votes on 0 Posts
Wire Derating - 30 Amps

When wiring 30 amps for a generator, whether it be for the portable cord or the *inlet* run, am I supposed to derate and use 8 AWG versus 10.

All the *off the shelf * generator cables all seem to be using 10AWG
Sponsored Links
Old 03-17-14, 07:32 AM
Justin Smith's Avatar
Join Date: Dec 2010
Location: Cressona, Pa, USA
Posts: 2,546
Received 0 Votes on 0 Posts
You are not required to, however I usually try to.
Old 03-17-14, 07:37 AM
Thread Starter
Join Date: Jul 2009
Location: NYC
Posts: 302
Received 0 Votes on 0 Posts
Axis of Overkill or not

The L14 won't work with 6 Wire
However, buy once cry one.

I've been thinking I might just pull 6/3-8/1 for the inlet.
I'll have to splice it to a smaller wire gauge for the L14.
Maybe to *some eyes*, it might look hodge-podged.

The bigger gauge wire will always be there, IF I need to upsize once more.

Bad Idea ?
Old 03-17-14, 09:50 AM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 57,123
Received 841 Votes on 788 Posts
The portable line set is in free air.

Inside the house under 35' I use #10. Over that and I'll upsize to #8.
#6 would be overkill for a portable generator connection.

Derating comes into effect with more than three current carrying conductors.
Old 03-17-14, 06:29 PM
Forum Topic Moderator
Join Date: Sep 2005
Location: USA
Posts: 5,135
Received 84 Votes on 79 Posts
Also remember 30A @ 240v = 7200 watts. Many generators with 30A outlets are under 7200w running watts. Since derating is based on power (watts), it's rare that you'd need to derate to a larger than 10ga wire for a reasonably sized generator.

Unless you have a long run, I don't think it's worth upsizing the wire from the generator, especially with the termination issues you'll run into.
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Thread Tools
Search this Thread
Ask a Question
Question Title:
Your question will be posted in: