Using #14 wire for one light on 20A breaker

[Don Klipstein]

I did state that my "does not increase at all" was a code matter, on which I would concede on appliance cords but I insist remains the case with romex.

So you have cited a data point opposing my point as well as a data point supporting my point (200C single conductor in free air good for 45 amps).

Sure is true with most wiring, such as permanently installed wiring! Code says 15 amps for AWG 14 regardless of temperature rating for permanently installed wiring!

I google for that and find a nice chart:

I see close to the top a line entry for 14 AWG, with no ampacities being the 15 amps for 14 AWG permanently installed wiring, and I have already conceded on the specific issue of appliance cords. Along with this chart showing higher ampacities for specific cable types of which I think 97% or so is not "permanently installed wiring". In addition, the code's limits for "permanently installed wiring" do not appear to me to be increased above 15 amps for 14 AWG or 20 amps for 12 AWG on the basis of such wiring being allowed for "permanently installed wiring" (most of these cable types are not) and such cable types having special ampacity higher than 15 amps for 14 AWG and 20 amps for 12 AWG.

But does the Code allow AWG 14 with THNN insulation to be used in permanently installed wiring in a building in circuits protected by fuses or breakers of more than 15 amps? Since I conceded on appliance cords, I still consider the issue of permanently installed wiring to be valid!

Starting to sound like what I am saying, especially in terms of code?

- Don Klipstein ( [e-mail])

[Professional]

[Doug Miller]

Yes, you did -- and I have repeatedly pointed out that this is not correct, that the Code absolutely does recognize increased ampacity with increasing conductor temperature.

The entire Code is online here:

I refer you to Table 310.16.

You're commenting in a vacuum, based on a lack of knowledge. Read the Code. You're wrong.

Read the Code. You're wrong. Table 310.16.

Read the Code. You're wrong. Table 310.16.

Read the Code. You're wrong. Table 310.16.

No -- but that's because the Code builds the "80% rule" into the overcurrent protection limits for 10, 14, and 12ga conductors, not because of any limits on the conductor's ability to carry current. It's for additional safety. But if you would actually READ THE CODE, you'd find out that the ampacities are in fact considerably higher than the permitted overcurrent protection. It's two separate issues.

Read the Code. You're wrong. Table 310.16.

No, it's NOT starting to sound like what you're saying. You said that, according to Code, conductor ampacity "does not increase at all" with increased conductor temperature rating, and that simply is not true. Not for fixture wires. Not for appliance cords. Not for permanently installed wiring. Not true at all.

READ THE CODE.

Table 310.16.

[terry]

. Exactly:

Had one situation where we realzed that a circuit extended out to shed from a 20 amp circuit included some #14AWG.

We quickly changed out the 20 amp breaker to 15 amp not because of any problems but a) to meet code b) Demonstrate for an in impending insurance inspection (the first in the 36 years since house was built!) that wiring was built and maintained to standard.

Reminds me got one cracked duplex at the bench must change it. And although its indoors think I'll make the first one on that run a GFI.

[Don Klipstein]

In , Doug Miller wrote in part:

OK, I learned something here - the issue that I was thinking of, where

15 amps is the limit for AWG 14 permanently installed wiring regardless of its temperature rating, is called "permitted overcurrent protection".

- Don Klipstein ( [e-mail])

[John]

This is a do-it-yourself NG. What are you doing here?

John