UL E18679 and NM ampacity

[yreme]

Where does it say what insulation/wire type is used for the conductors in NM cable ?

 

[Dennis Alwon]

Where does it say what insulation/wire type is used for the conductors in NM cable ?

Going from memory 334.100?

 

[chris kennedy]

334.104 for starters.

 

[chris kennedy]

Going from memory 334.100?

Insert old age joke here.

I'll give you a break.:smile:

 

[SEO]

334.112 insulation.

 

[Dennis Alwon]

Insert old age joke here.

I'll give you a break.:smile:

Hey I was close--- Not by the book and too lazy to go upstairs. Or perhaps too old to go upstairs. :smile:

 

[chris kennedy]

334.112 insulation.

I see my memory is in question also.:smile:

 

[chris kennedy]

Hey I was close--- Not by the book and too lazy to go upstairs. Or perhaps too old to go upstairs. :smile:

My elbow was resting on mine and I was too lazy to open it. I will repent.

 

[SEO]

I see my memory is in question also.:smile:

My memory is very good but it is also very short.:smile:

 

[Dennis Alwon]

Let's be clear that art.334.112 states the wire must be 90C not any particular insulation type.

 

[SEO]

I agree with that.:smile:

 

[celtic]

I don't think the question has been answered....

334.112 Insulation.
The insulated power conductors shall be
one of the types listed in Table 310.13 that are suitable for
branch circuit wiring or one that is identified for use in these
cables. Conductor insulation shall be rated at 90?C (194?F).

That really doesn't tell us too much, does it?


I wonder what the OP is really asking?

 

[tom baker]

While the conductors in NM are 90 Deg C rated, they have no markings. They are not intended to be used as individual conductors in a raceway.

 

[e57]

I'm sure to be corrected if wrong:

Nylon jacketed PVC, not listed in 310.16 or as an insulation type. Actually rated at either 60 or 75, but 90 table allowed for derating.....

Wait:

NM-B: Nonmetallic-Sheathed Cable. The "B" denotes that individual conductor insulation is rated 90?C; however, ampacity is limited to that for a 60?C conductor (see NEC Section 336-26, 1999 edition). Thermoplastic (PVC) conductor insulation-nylon jacketed, with overall PVC cable jacket.

Ref: (See "ampacity" in NM, in whatever code you happen to be on)

 

[yreme]

maybe i didn't ask...

maybe i didn't ask...

the correct question

if the wire was marked, what would it be, thhn , rhw... ? and i know 334. the wire internal to the outer sheath doesn't have any reference to any of the types listed in table 310.16 and i dodn't recall finding it on the packaging of the coil. what are we using to determine it's rating other than someone at sometime in the beginning of you electrical career said, ok, use the 14-2 for that 15 amp circuit.

 

[raider1]

what are we using to determine it's rating

Take a look at 334.80.

Chris

 

[celtic]

maybe i didn't ask...the correct question

if the wire was marked, what would it be, thhn , rhw... ? and i know 334. the wire internal to the outer sheath doesn't have any reference to any of the types listed in table 310.16 and i dodn't recall finding it on the packaging of the coil.

...and you won't.
It is a mystery ~ seriously.

what are we using to determine it's rating other than someone at sometime in the beginning of you electrical career said, ok, use the 14-2 for that 15 amp circuit.

334.80

Use T310.16 and the 90? column for derating, as long as your calculated result does not exceed the 60? column.

Also...don't forget 240.4(D)