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#44454 11/04/04 04:18 PM
Joined: Jun 2003
Posts: 1,143
DougW Offline OP
OK... We all know what the Code says:

A general term including material, fittings, devices, appliances, fixtures, apparatus, and the like used as a part of, or in connection with, an electrical installation.
An accessory such as a locknut, bushing, or other part of a wiring system that is intended primarily to perform a mechanical rather than electrical function.
The conductor and equipment required or permitted by this Code shall be acceptable only if approved.

OK, it's a long intro for this:

(Sorry for the link - not sure how to post pic)

I remembered one of my foremen when I first started who had a tray of nipples similar to this one - a tray of 1/2", and a tray of 3/4". All galvanized, varying in lengths from close to 6". We used them for going through exterior walls for A/C disconnects and exterior W/P receptacle boxes, as it tool less time (and a smaller hole) than messing around with compression fittings.

Thinking back now, I don't remember them being UL listed (no little blue & silver sticker), and I now wonder if he was using regular "plumbing" nipples instead of UL "electrical" nipples. We made sure the ends were reamed smooth and everything was secure, and I don't remember getting red tagged on it.

Does anybody have a supplier who offer a pre-sorted "selection" of Listed nipples of various lengths like they have for plumbers? Has anybody used a plumbing nipple in a pinch?

Just being curious.

[This message has been edited by DougW (edited 11-04-2004).]

Joined: Apr 2001
Posts: 518
Don't hardly ever use nipples- use 'running thread' instead. It's always the right length!

Joined: Dec 2003
Posts: 524
... I thought "running threads" were a violation.I remember reading in the "good book",.."no running threads,and no more than a 3/4"/ft taper on threads...What exactly are running threads, it like a long close nipple??
Honestly,I'm confused, I don't do much work with rigid pipe,but I'd still like to know....Thanx,

.."if it ain't fixed,don't break a Licensed Electrician"
Joined: Sep 2004
Posts: 86
342.42(B) and 344.42(B) states that running thread is only prohibited when used to connect couplings. Must mean running thread can be used anywhere else. I may just look into using running thread. Nice to learn new techniques through this site.

Joined: Dec 2000
Posts: 4,294
I have to confess to using plumbing nipples occasionally when I was "needy". They were always reamed carefully to take off the nasty sharp edge.

What exactly are running threads, it like a long close nipple??

Russ, running threads are sometimes called "allthread", too. It's just a piece of GRc with a continuous thread. It's usually sold in 3 foot sections (and costs a lot).
Standard pipe threads have a taper of 3/4" per foot. Running thread has no taper, the threads are straight.
It's great stuff for cutting into short lengths for use with locknuts for connecting enclosures together, etc.; an "adjustable nipple", so to speak.
Conduit couplings, unlike plumbing fittings, are also made with a straight thread. You can take one and spin it all the way up and down a piece of running thread much like a nut would run up a piece of threaded rod.

Joined: Apr 2004
Posts: 156
Nipples can be bought per size or made to fit. Rigid metal conduit is UL approved, you just have to cut to length and make sure it is reamed and threaded properly.

Now using black steel pipe has been a big no-no every place I have ever worked. I have done alot of work on Explosion Proof and just using nipples to get through walls. I don't use continous threads, especially on mobile equipment where vibration can cause couplers/locknuts to walk off of the fitting.

Joined: Mar 2001
Posts: 2,056

When I first started "Expolsion-Proof" work in 1984, I remember there being a "UL" sticker on each and every nipple (Galvanized Rigid Steel) that we bought.
At the time, it seemed excessive.
I guess the manufacturers thought so too, because come to think of it, I don't recall seeing the stickers for at least several years.

Joined: Jan 2003
Posts: 4,391
Nipples can be bought per size or made to fit. Rigid metal conduit is UL approved, you just have to cut to length and make sure it is reamed and threaded properly.

Yes you can cut and thread RMC in the field however making short nipples in the field is tough.

The cutting die ends up hitting the vice or chuck supporting the short length of RMC.

Bob Badger
Construction & Maintenance Electrician
Joined: Mar 2001
Posts: 2,056

A "nipple chuck" attachment is necessary to field thread short nipples.
You can even thread close nipples with it.
If you do a lot of threaded rigid, you should try to get one.

Joined: Mar 2003
Posts: 97
To make a short nipple without a nipple chuck.

Run a long thread say 6 inches or so, long enough so the threader will not hit it from the other side.

Flip pipe over and clamp it on the threaded part.

Measure, cut and thread the other side.

Flip over again and cut the excess thread off.

Yeah, its wasteful but if you need ONE 2 inch long nipple to finish the job on a weekend when they will inspect on monday....

Can also use a long piece of pipe with the nipple coupled to it. Problem is after threading the coupling will either be broken or real hard to get off.

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