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Joined: Jul 2004
Posts: 9,687
Likes: 10
... when they moved good old table 310.16 that has been around since electricity that they changed the ampacity of 14ga and 12ga in the 60c column? (Table 310.15(B)(16) now)

Or am I just missing something?
It is insignificant in regular branch circuits because of 240.4(D) but that will affect motor circuits.
I am a bit ashamed it took me 4 years to see that (the 14 was actually only adopted here this year) but I am retired and not looking at this every day.

Greg Fretwell
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Joined: Jan 2018
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Changes were made in the 2011 NEC. Found the following explanation (extracted from a longer article about the 2011 changes).

"The ampacity of some conductors in Table 310.15(B)(16) (formerly 310.16) didn’t match those found in the Canadian Electrical Code and were therefore changed. While no technical evidence was submitted showing insulation failure of the conductors, this proposal was passed. The end result was a change to the ampacities of:

Copper conductors: 14, 12, 3, and 1 AWG, and 600kcmil, 1,500kcmil and 2,000kcmil.

Aluminum conductors: 12, 8, and 6 AWG, and 300kcmil, 700kcmil, and 800kcmil."

Joined: Jul 2004
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I am really surprised I didn't hear much about that. It certainly changes the answer to that question on the inspector test about a 120v 1HP motor with 14ga wire.

Greg Fretwell
Joined: Apr 2002
Posts: 7,296
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No, you are not alone on this. I just ‘discovered’ this today. (Frown)

Joined: Jul 2004
Posts: 9,687
Likes: 10
Like I say, this certainly throws a monkey wrench into what you can do in motor circuits. I keep thinking there is an exception I haven't found. I got my CEUs online 4 years ago based on the 11 code and I do not remember this being brought up. I did know 310.16 was moved but I never heard it was changed. That is the problem with being retired. I am not really paying that much attention these days. I didn't even renew my license last year so I didn't take the 14 updates. I really miss the face to face classes tho. I am sure the seminar guys were talking about this.

Greg Fretwell
Joined: Oct 2000
Posts: 5,390
Proof old dogs rule Greg

go you!


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