UF cable table 310.16?

[panhandle444]

Why is UF cable rated a 60 degrees celcius column?

Wouldn't being in the ground be cooler and have a lower ambient temperature. Or does the heat not dissipate?

 

[Hv&Lv]

Why is UF cable rated a 60 degrees celcius column?

Wouldn't being in the ground be cooler and have a lower ambient temperature. Or does the heat not dissipate?

It isn't always in the ground. it has to come to the panel somewhere. it can be used in the structure just like NM also for flooding houses.

 

[Dennis Alwon]

I agree that it is often run inside a building but they could rate it 75C when it is underground and not entering a structure or going thru insulation

 

[kwired]

I think it is to be used at 60^o C rating for same reason NM cable is, although I really don't know what that reason is.

You can still use 90^o C rating for a starting point for derating just like NM, unless dealing with an older cable that does not have individual 90^o C conductors.

 

[jumper]

I think it is to be used at 60^o C rating for same reason NM cable is, although I really don't know what that reason is.

You can still use 90^o C rating for a starting point for derating just like NM, unless dealing with an older cable that does not have individual 90^o C conductors.

You sure about that............


340.80 Ampacity. The ampacity of Type UF cable shall be
that of 60?C (140?F) conductors in accordance with 310.15.

 

[kwired]

You sure about that............


340.80 Ampacity. The ampacity of Type UF cable shall be
that of 60?C (140?F) conductors in accordance with 310.15.

Well maybe I'm not so sure. 340.80 is pretty simple compared to 334.80 isn't it?

Guess I should look before saying such things.

 

[CONDUIT]

Evidently there is a "UF-B". Look at the link below.

http://www.southwire.com/products/UFBOEM.htm

 

[infinity]

Shouldn't all UF be manufactured with 90? C conductors?

340.112 Insulation. The conductors of Type UF shall be
one of the moisture-resistant types listed in Table
310.104(A) that is suitable for branch-circuit wiring or one
that is identified for such use. Where installed as a substi-
tute wiring method for NM cable, the conductor insulation
shall be rated 90?C (194?F).

 

[fmtjfw]

2012 UL White Book

2012 UL White Book

UNDERGROUND FEEDER AND BRANCH CIRCUIT CABLE (YDUX)
GENERAL
This category covers underground feeder and branch circuit cable, rated 600 V, in sizes 14 to 4/0 AWG inclusive, copper, and 12 to 4/0 AWG inclusive, aluminum or copper-clad aluminum, for single and multiple conductor cables. It is designated as Type UF cable and is intended for use in accordance with Article 340 of ANSI/NFPA 70, ??National Electrical Code??
(NEC).
Some multi-conductor cable is surface marked with the suffix ??B?? immediately following the type letters to indicate the usage of conductors employing 90?C rated insulation.
Such cable may also be installed as Nonmetallic-sheathed Cable, per Section 340.10(4) of the NEC. The ampacities of Type UF cable, with or without the suffix ??B,?? are those of 60?C rated conductors as specified in the
latest edition of the NEC.

 

[infinity]

So I'm guessing that any installation of UF cable in dry locations would require the -B marking and 90? conductors.

 

[fmtjfw]

Don't know

Don't know

340.112 Insulation. The conductors of Type UF shall be one of the moisture-resistant types listed in Table 310.104(A) that is suitable for branch-circuit wiring or one that is identified for such use. Where installed as a substitute wiring method for NM cable, the conductor insulation shall be rated 90?C (194?F).

I don't know if a continuous length of UF from "outside" would be allowed at 60?C, it would meet the ampacity and as long as it didn't got to something like a 90?C lighting fixture (rather to a switch or CB) I'd have no problem with it.

I had a similar argument about NM versus NM-B in an earlier post.