Modifying the length of an RMC nipple

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Carultch

Senior Member
Location
Massachusetts
I'd like to ask if it is possible to modify the length of an RMC nipple, such that the new length will still contain the factory threads. And then afterwards, the threads would need to be re-cut in alignment with the existing threads.

Is it practical to expect an electrician to be able to do this?
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
I'd like to ask if it is possible to modify the length of an RMC nipple, such that the new length will still contain the factory threads. And then afterwards, the threads would need to be re-cut in alignment with the existing threads.

Is it practical to expect an electrician to be able to do this?

Well you could probably cut the nipple in the middle and use a compression union, but this won't work with a pipe full of wire without pulling them first.
 

ADub

Senior Member
Location
Midwest
Occupation
Estimator/Project Manager
Modifying the length of an RMC nipple

I'd like to ask if it is possible to modify the length of an RMC nipple, such that the new length will still contain the factory threads. And then afterwards, the threads would need to be re-cut in alignment with the existing threads.

Is it practical to expect an electrician to be able to do this?

Trying to cut a piece in the threads and then re-thread is a pain but far from impossible. I would expect every electrician that's spent some time running rigid could handle this task easily. Obviously you're better off cutting and threading your own piece the first tine
 

jusme123

Senior Member
Location
NY
Occupation
JW
...you could explain it a little bit better, why not just make new nipple
 
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ActionDave

Chief Moderator
Staff member
Location
Durango, CO, 10 h 20 min from the winged horses.
Occupation
Licensed Electrician
I'd like to ask if it is possible to modify the length of an RMC nipple, such that the new length will still contain the factory threads. And then afterwards, the threads would need to be re-cut in alignment with the existing threads.

Is it practical to expect an electrician to be able to do this?
What length nipple?
 

Johnnybob

Senior Member
Location
Colville, WA
I'd like to ask if it is possible to modify the length of an RMC nipple, such that the new length will still contain the factory threads. And then afterwards, the threads would need to be re-cut in alignment with the existing threads.

Is it practical to expect an electrician to be able to do this?

Yup, I do it all the time, and not just nipples. Some times the pipe is jast a 1/4 to 3/8 long of looking pretty, so I just cut a few threads off, chuck it up in the 300 (or tri-stand if hand threading uhh) ream it and thread it. If it's a close nipple, you'll need a nipple chuck.
 

Carultch

Senior Member
Location
Massachusetts
...you could explain it a little bit better, why not just make new nipple


The context here is that I've got an assembly of elbows and nipples picked out according to how it all lays out in theory. All factory sizes. The issue I'm anticipating is what to do when it doesn't work out in practice, and Suppose you start with an 8" nipple, but you determine that it needs to be a 7.5" nipple. Does this mean that you have to scrap the 8" nipple, and start with a 10"? Or does it mean that you can cut the 8" to 7.5", and resume cutting in line with the existing threads?

I don't have much experience, but the people building it have plenty. I mainly want to make sure they are prepared.
 

Cow

Senior Member
Location
Eastern Oregon
Occupation
Electrician
Or does it mean that you can cut the 8" to 7.5", and resume cutting in line with the existing threads?

We do it all the time. Sometimes you're a little off on the measurements or for some reason the one you just cut doesn't fit. You'll cut it shorter with the portaband, and chuck it up in the threader. You can drop the dies right back into the existing threads when you go to rethread it.
 

ADub

Senior Member
Location
Midwest
Occupation
Estimator/Project Manager
The context here is that I've got an assembly of elbows and nipples picked out according to how it all lays out in theory. All factory sizes. The issue I'm anticipating is what to do when it doesn't work out in practice, and Suppose you start with an 8" nipple, but you determine that it needs to be a 7.5" nipple. Does this mean that you have to scrap the 8" nipple, and start with a 10"? Or does it mean that you can cut the 8" to 7.5", and resume cutting in line with the existing threads?

I don't have much experience, but the people building it have plenty. I mainly want to make sure they are prepared.

It's very possible to shorten and rethread rigid conduit. Rethreading rigid elbows I've never attempted nor would I. Doing this with shorter nipples would be tedious and frustrating work since it'd make way more sense to set up and cut/thread the lengths you need as you need them. Long story short what you want to do is possible but it's probably going to upset whoever has to actually build these things
 

tkb

Senior Member
Location
MA
The context here is that I've got an assembly of elbows and nipples picked out according to how it all lays out in theory. All factory sizes. The issue I'm anticipating is what to do when it doesn't work out in practice, and Suppose you start with an 8" nipple, but you determine that it needs to be a 7.5" nipple. Does this mean that you have to scrap the 8" nipple, and start with a 10"? Or does it mean that you can cut the 8" to 7.5", and resume cutting in line with the existing threads?

I don't have much experience, but the people building it have plenty. I mainly want to make sure they are prepared.

Planning the conduit run on paper and ordering the fittings makes good sense if you know the layout and have the time, but I would plan on at least one field cut and thread per run to allow for the field conditions and the inconsistency of the factory elbows and nipples.
 

Fulthrotl

~Autocorrect is My Worst Enema.~
The context here is that I've got an assembly of elbows and nipples picked out according to how it all lays out in theory. All factory sizes. The issue I'm anticipating is what to do when it doesn't work out in practice, and Suppose you start with an 8" nipple, but you determine that it needs to be a 7.5" nipple. Does this mean that you have to scrap the 8" nipple, and start with a 10"? Or does it mean that you can cut the 8" to 7.5", and resume cutting in line with the existing threads?

I don't have much experience, but the people building it have plenty. I mainly want to make sure they are prepared.

ok, you need it 1/4" shorter? cut it off with the saw, ream it,
and take the porta pony, and start it on the pipe, squirt some
lube on it, and it'll continue the thread perfectly.
 

Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
Run a good quality lock nut all the way up the threads before cutting, then when you take it off after cutting, it straightens out the damaged thread edges where you cut. You still have to run back over it with a threading die to re-thread it longer, but that way your die teeth don't get hung up on the burrs and start cross threading.
 

tkb

Senior Member
Location
MA
A thread file or small triangular file would also be helpful to fix the threads.
 

Carultch

Senior Member
Location
Massachusetts
Huh?

Any RMC compression fitting is fine for wet locations.

Not true. Most datasheets for RMC compression fittings indicate concrete tight, but nothing regarding raintight or direct burial. There is a passage in 344, that specifically requires threadless fittings to be listed for wet locations or equivalent.
 

Cow

Senior Member
Location
Eastern Oregon
Occupation
Electrician
I looked through our local Platt's website. It seems the Appleton brand are concrete tight, and the Made in USA American Fittings Corp are both rain and concrete tight for just a little more money.
 

Carultch

Senior Member
Location
Massachusetts
Not exactly sure why your cutting a factory nipple. Why not make your own. if you don't have a nipple chuck buy some running thread and cut to length


Because why start with 10 ft of conduit, when you only intend to use less than a foot?

Also, "running thread" has limited applications, that I do not fully understand. It probably is due to the fact that the threads are straight instead of tapered, and don't connect properly to other fittings such as couplings.
 
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