RMC terminations

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Twoskinsoneman

Twoskinsoneman

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Location
West Virginia, USA NEC: 2020
Occupation
Facility Senior Electrician
I've never worked with rigid metal conduit, as silly as that sounds. Are all RMC terminations threaded? I know I see EMT cut to length and terminated with what looks like a sleeve with a friction screw. Seem "cheesy" but I guess everything has it's proper use and place. Does RMC always terminate in a thread fitting? If so do you guys have to tap the end of your pipe at every box? That seems pretty unlikely.
 
Should of done my homework first.

Should of done my homework first.

This forum is so informative I sometimes come here even before I open the NEC. 344.42 clearly allows a threadless fitting. I am still interested to know if more electricians use these threadless fittings or if having your own tap in the field is pretty much standard.
 
After you see the price of threadless fittings you see why it is not the prefered method.

Typically we only use threadless fittings in a pinch or a small project where only a couple will be needed.

Roger
 
Twoskinsoneman....For your info.

A "Tap" is used to cut internal threads.

A "Die" is used to cut external threads...like the threads on a pipe.

I don't own any Pipe Taps.

I do own a full set of Pipe Dies from 1/2" thru 3".

steve
 
hillbilly said:
Twoskinsoneman....For your info.

A "Tap" is used to cut internal threads.

A "Die" is used to cut external threads...like the threads on a pipe.

I don't own any Pipe Taps.

I do own a full set of Pipe Dies from 1/2" thru 3".

steve
Click to expand...

Thanks for the correction steve. To be honest I did know the difference. The reason I said tap was the convience of using the word as a verb as in "go tap the pipe". I figured it would be acceptable. I'm not sure you could use "die" the same way. "Go die the pipe".

It's cool that you have your own set. I know having the right tools quickly pays for it'self it most cases.
 
Twoskinsoneman said:
Thanks for the correction steve. To be honest I did know the difference. The reason I said tap was the convience of using the word as a verb as in "go tap the pipe". I figured it would be acceptable. I'm not sure you could use "die" the same way. "Go die the pipe".
Click to expand...


We would say "go thread the pipe". Since you would use a die in a threading machine.
 
Twoskinsoneman said:
This forum is so informative I sometimes come here even before I open the NEC. 344.42 clearly allows a threadless fitting. I am still interested to know if more electricians use these threadless fittings or if having your own tap in the field is pretty much standard.
Click to expand...

Choices include:
- Thread the pipe
- Use one of two threadless fittings ~ compression or set screw
- Use a plastic bushing designed for the purpose (usually only on data runs)


To further add to the bashing your getting on the whole "tap" thing :D ...
If 344.42 allows "threadless", wouldn't you think they are talking about threads and not taps?
:D
(Just havein' fun at your expense...no offense intended)
 
I may be wrong here but if you were burying RMC I don't think the threadless connectors are approved. Is that correct?
 
celtic said:
Choices include:
- Thread the pipe
- Use one of two threadless fittings ~ compression or set screw
- Use a plastic bushing designed for the purpose (usually only on data runs)


To further add to the bashing your getting on the whole "tap" thing :D ...
If 344.42 allows "threadless", wouldn't you think they are talking about threads and not taps?
:D
(Just havein' fun at your expense...no offense intended)
Click to expand...

Nice.
I'm never offended at being corrected. Only an idiot thinks he can never be wrong. I'm sure I can be wrong...I just never have been yet:grin:
 
Twoskinsoneman said:
Nice.
I'm never offended at being corrected. Only an idiot thinks he can never be wrong. I'm sure I can be wrong...I just never have been yet:grin:
Click to expand...

Glad to see you maintain a sense of humor :)
 
Several factors come into play here, the biggest one being the availability of a threader, and what type of threader it is. If I can't thread the pipe, then I have no choice but to use threadless fittings.

I can thread quite a few small size (1/2 & 3/4) with a hand threader, and still want to come to work the next day. More than a half-dozen 2", and I've about had it. I'm not 25 anymore. I can run a power threader all day long though.

It also depends on bends in the pipe. Small sizes can be bent, cut, and threaded by hand. Bigger sizes are much more difficult, if not outright impossible. Threadless fittings might not look the best, but we need to factor labor in here somewhere.
 
There is nothing illegal about a threadless. But, just as a side note, not using threadless fittings (or Eriksos for that matter) tends to be a point of pride for many electricians. Persoanlly, I try not to use them on larger runs, but in a pinch they are damn handy (especailly on a small job where dragging the threader out is more time and labor than it's worth.)

Incidentally, Micromind, the trick is to calculate your take ups and shrinkage and thread the pipe before you bend it.
 
Threadless

Threadless

roger said:
After you see the price of threadless fittings you see why it is not the prefered method.

Typically we only use threadless fittings in a pinch or a small project where only a couple will be needed.

Roger
Click to expand...

No one mentioned the absolute need for threadless fitting and probably why invented is at the end of a run or where two conduits meet from different directions you cant make the conection unless you loosen the conduit by turning in wrong direction which is agaist code. Joints must be pulled up tight.
 
The threadless couplings are great when you don't have a lot of room to work with. Also when I lived in Vermont we had to coat rigid with a tar like substance if we were going to direct bury.
 
jetlag said:
No one mentioned the absolute need for threadless fitting and probably why invented is at the end of a run or where two conduits meet from different directions
Click to expand...

You can use a threadless fitting for that but you don't need to.

You can use a 'three piece coupling', which if we where plumbers we would call it a 'Union'

Three-Piece-ex.jpg
 
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jetlag said:
No one mentioned the absolute need for threadless fitting and probably why invented is at the end of a run or where two conduits meet from different directions you cant make the conection unless you loosen the conduit by turning in wrong direction which is agaist code. Joints must be pulled up tight.
Click to expand...
They also make a left/right coupling that will work.
 
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