Rigid Threader

[brother]

looks like it is NPT for electrical conduit.

a) Use a standard 3/4 inch per foot taper National
Pipe Thread (NPT) die. The threads shall be cut full
and clean using sharp dies.

http://www.steelconduit.org/pdf/ConGuide.pdf

 

[iwire]

Not sure what to make of this. I just went out and grabbed a piece of 3/4? Columbia MBF RMC off the rack and unthreaded the coupling, by hand I might add. Straight factory threads with no taper, so is my conduit is bad?

Well I don't know, an RMC threaded coupling has straight threads, the RMC has tapered threads. If you section of galvanized pipe has straight threads it is either

1) Not UL listed RMC

2) Some mongrel pipe someone slapped a UL sticker on

3) You made a mistake.

My pitch gauge, dies and other actual female NPT and IPS pipe fittings all tell me this particular thread is not NPT.

Don't know what to tall you, bad pitch guages, mislabeled etc.

Not trying to give you a hard time, welcome to the forum. :smile:

 

[mattsilkwood]

what kind of threader is that ??

its a ridgid 1224. do you have one too smart? its a cadilac.

 

[KJay]

Well I don't know, an RMC threaded coupling has straight threads, the RMC has tapered threads.
QUOTE]
I?m not trying to piddle in anyone's corn flakes, but just to throw a little more poop at the fan, how can this comply with 505.9,[E].

 

[tom baker]

Plumbing couplings have a taper.
Electrical do not.
An electrical coupling in a water line will leak.

 

[don_resqcapt19]

Well I don't know, an RMC threaded coupling has straight threads, the RMC has tapered threads.
QUOTE]
I?m not trying to piddle in anyone's corn flakes, but just to throw a little more poop at the fan, how can this comply with 505.9,[E].

You just have to find some of the old Canadian Code conduit couplings...about 20 years ago their code required the use of tapered thread couplings, but the changed their code under pressure from the conduit manufacturers.

 

[Smart $]

its a ridgid 1224. do you have one too smart? its a cadilac.

I have used several, but don't own one myself. Yes, it is the cadilac of threading machines.

 

[sandsnow]

I used some Rigid dies my Dad had from the fifties on some gas line I was running and they did not hold test. I also have dies that are marked conduit. I will post some pix later.

So maybe this is a relatively recent thing?

Around here in the jobs I inspect, an electrician with a threader is like a plumber with lead and okum.

 

[KentAT]

From the Q&A section on the www.steelconduit.org website:

Q: 14. What type of threads are cut on RSC and IMC?
A: 14. The NEC requires that the threads of both RSC and IMC be cut with a 3/4 inch taper per foot (1 in 16) per ANSI/ASME B.1.20.1 Standards for Pipe Threads, General Purpose (Inch). This applies to both factory and field threads. This is the same taper as standard plumbing pipe.

 

[LarryFine]

All of these different answers as to thread styles, and nobody even had to look in a bible. :wink:

Around here in the jobs I inspect, an electrician with a threader is like a plumber with lead and okum.

So, what does the modern electrician use where you are?

 

[wireguru]

So, what does the modern electrician use where you are?

compression fittings! (project specs and appearance be damned)

 

[sandsnow]

All of these different answers as to thread styles, and nobody even had to look in a bible. :wink:


So, what does the modern electrician use where you are?

All I see are gas stations. 10' stick bent to stub height and and the lenght between the building and the pumps made up with PVC.

On the roof, EMT with raintight fittings.

 

[brother]

Never knew this thread would have soo many responses. At least i found the answer to my question.lol

so now im wondering , are rigid couplings (threaded type)actually allowed in wet locations??

 

[celtic]

so now im wondering , are rigid couplings (threaded type)actually allowed in wet locations??

Yes they are.
Threadless type would need raintight type.

 

[KJay]

Kjay there is no requirement or expectation that RMC couplings will be water tight, the couplings are straight thread. Conduit threads are in fact NPT.

I think I smell irony?. or possible something else! :grin:
Why is the NEC so concerned with requiring the new raintite fittings for EMT?
Seems they require NPT threads for RMC to be used where they are not needed, then by design, allow the use of straight thread couplings with RMC in wet locations, including direct burial and classified locations.

 

[iwire]

I think I smell irony?. or possible something else! :grin:
Why is the NEC so concerned with requiring the new raintite fittings for EMT?

I don't know, it is a good question and has been discussed here many times.

I think the issue may have come down to the EMT compression fittings claimed to be watertight but where not.

Threaded RMC couplings have never claimed to be water tight.

:-?

 

[sandsnow]

here's one example of a die marked for conduit. Probably at least fifty years old.