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#97879 - 04/11/06 10:38 AM URD
Tripp Offline

Registered: 09/20/05
Posts: 101
Does URD (aluminum direct burial cable) go by a different name in the NEC? I'm looking for it in 310.16 and in ch.9 Tables 5 and 8 to calculate the proper size to use.

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#97880 - 04/11/06 11:55 AM Re: URD
feather Offline

Registered: 02/28/06
Posts: 25
Loc: Santa Maria CA USA
Here at the plant, URD is underground residential distribution cable. Typically, MV rated 15kv and up sold to POCO. Do you mean USE underground service entrance cable? Then table B.310.9 plays, I hope I haven't confused the issue. Chuck

#97881 - 04/11/06 02:48 PM Re: URD
Tom Offline

Registered: 01/01/01
Posts: 1069
Loc: Shinnston, WV USA
URD is not one of the conductor constuctions that is recognized by the NEC. Unless it has some other marking such as "XHHW" "RHW" then it would be a code violation to use it anywhere the NEC applies. See 310.13

Typically, the URD that I've run across is purchased because it is much less expensive than one of the correct cables or conductors. I've had to give the sad news to a lot of mobile home owners about this cable. Word has finally gotten around & the hardware stores are no longer selling it and it has been some time since I've seen a new piece of URD.
Few things are harder to put up with than the annoyance of a good example.

#97882 - 04/11/06 07:46 PM Re: URD
Tripp Offline

Registered: 09/20/05
Posts: 101
Well, this is confusing. I've worked in this locale for 7 years and everyone I know refers to this as URD. I shop at an electrical distibutor(wholesale house), not at a BigBox store or ma-n-pa hardware store, and they sell it as "URD". This is direct burial cable consisting of three aluminum conductors entwined with each other (I think one of the conductors has a reddish stripe, perhaps to distinguish it as the neutral). I've always wondered exactly what USE looked like, so maybe this is it. I guess I'll just stop by the wholesale house tomorrow and look closely at the wire itself to see exactly how it is labeled.
In the meantime, anyone else have an opinion?

#97883 - 04/11/06 07:56 PM Re: URD
Tripp Offline

Registered: 09/20/05
Posts: 101
Feather: I'm further confused by your mention of "table B.310.9." In this in the NEC? Not in my book. Just wondering.

#97884 - 04/12/06 01:57 AM Re: URD
iwire Offline

Registered: 01/05/03
Posts: 4343
Loc: North Attleboro, MA USA
B.310.9 is in Annex B at the rear of the code book.

Those tables are not for general use, they are for use by engineers.

B.310.15(B)(1) Formula Application Information.
This annex provides application information for ampacities calculated under engineering supervision.

Bob Badger
Construction & Maintenance Electrician

#97885 - 04/12/06 08:18 AM Re: URD
raider1 Offline

Registered: 07/08/05
Posts: 46
Loc: north logan, utah, US
I believe that at least some of the cable that we call "URD" is in actuality a cable comprised of USE-2 conductors.

Here is a link to a cable company site for USE-2 cable


#97886 - 04/12/06 11:03 AM Re: URD
Tripp Offline

Registered: 09/20/05
Posts: 101
Went to the wholesale house today and found that what we all here refer to as URD is in fact labeled USE-2,RHH,RHW-2.

Apologies to Feather: Table B.310.9 is indeed in my codebook (thanks, Bob, for reminding of the annex I never visit).


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