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What's a nipple?? #37129
04/22/04 05:59 AM
04/22/04 05:59 AM
electure  Offline
OP
Member
Joined: Dec 2000
Posts: 4,263
Fullerton, CA USA
OK,
NEC'99 310-15(b)(2)(a)

Exception No. 3: Derating factors shall not apply to conductors in nipples having a length not exceeding 24 in. (610 mm).

So what exactly constitutes a nipple??

Work Gear for Electricians and the Trades
Re: What's a nipple?? #37130
04/22/04 06:24 AM
04/22/04 06:24 AM
G
George Corron  Offline
Member
Joined: May 2001
Posts: 717
Lorton, Va USA
A pipe not over 24" is a nipple.

Re: What's a nipple?? #37131
04/22/04 10:07 AM
04/22/04 10:07 AM
D
DougW  Offline
Member
Joined: Jun 2003
Posts: 1,143
North Chicago, IL
<<CENSORED>>

Never mind. George's answer is probably more appropriate for this forum!

Re: What's a nipple?? #37132
04/22/04 12:12 PM
04/22/04 12:12 PM
R
Ryan_J  Offline
Moderator
Joined: Aug 2003
Posts: 1,374
West Jordan, Utah, USA
I like George's answer. It is easy to overthink this. A 90 degree bend can be a nipple if it is less than 24".


Ryan Jackson,
Salt Lake City
Re: What's a nipple?? #37133
04/22/04 02:39 PM
04/22/04 02:39 PM
I
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
At first read you say why?

Why can I stuff 24" of pipe with wires and not derate?

I believe the answer lies in coppers ability to readily conduct heat.

Say you have a 24" nipple between a panel and a contactor enclosure, you will have conductors hanging out of both sides of the nipple acting like heat sinks limiting how hot the conductors in the nipple will get.

That's my story and I am sticking to it. [Linked Image]

After all there has to be logic behind this exception.

Bob


Bob Badger
Construction & Maintenance Electrician
Massachusetts
Re: What's a nipple?? #37134
04/22/04 03:37 PM
04/22/04 03:37 PM
F
frenchelectrican  Offline
Member
Joined: Feb 2003
Posts: 939
Wi/ Paris France { France for ...
i am leaing more to bob's answer there .

yes any pipes included the ell sweep[s] if 24 inch or less but i am still consering about the abilty of heat build up in there.

and for short pipe nipples 24 inch or less.

I have see few place some peoples did use 24 inch pipes and jamed many romax[s] wire in the pipe and i have one call not too long ago and have to replace bunch of romax wire they were brittle in few spots.

Really IMO,, i dont know if they did change the code or not about derating the wires in the nipples at all but i wish they change the length limit to more like 4 inch or less that can clear up some of the mess we have to deal with it ..

merci , marc


Pas de problme,il marche n'est-ce pas?"(No problem, it works doesn't it?)

Re: What's a nipple?? #37135
04/23/04 07:36 AM
04/23/04 07:36 AM
electure  Offline
OP
Member
Joined: Dec 2000
Posts: 4,263
Fullerton, CA USA
I like both George and Ryan's descriptions.
(the elbow was what I was looking for).

We had an inspector proclaim that by (his own) definition a nipple must be a straight piece of rigid conduit. (Although he couldn't explain the term "offset nipple")

Thanks...S

Re: What's a nipple?? #37136
04/23/04 09:00 AM
04/23/04 09:00 AM
T
ThinkGood  Offline
Member
Joined: Aug 2002
Posts: 1,081
Milwaukee, WI
Elbow and nipple:

[Linked Image]

[This message has been edited by ThinkGood (edited 04-23-2004).]

Re: What's a nipple?? #37137
04/23/04 10:05 AM
04/23/04 10:05 AM
Trumpy  Offline

Member
Joined: Jul 2002
Posts: 8,231
SI,New Zealand
Guy's if you want my input into the frey, a nipple as I understand it is a Male-Male Threaded coupling.
Ask any plumber what a nipple is, provided they are civilised, that will be thier answer.
Cue Russ!. [Linked Image]

Re: What's a nipple?? #37138
04/23/04 06:45 PM
04/23/04 06:45 PM
G
ga.sparky56  Offline
Member
Joined: Nov 2002
Posts: 558
young harris georgia usa
That would be my thought too Trumpy.

If it doesn't have threads at both ends most plumbers wouldn't call it a nipple,just a 24" length of pipe.

Russell

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