- Location
- Massachusetts
M. D. said:
Well said. :grin:
rigid conduit
- Thread starter j rae
- Start date
- Status
Well said. :grin:
kspifldorf
Senior Member
- Location
- My Old Kentucky Home
Wouldn't that be considered a voltage drip.:grin:tom baker said:
- Location
- New Jersey
- Occupation
- Journeyman Electrician
realolman said:seems to me if they were cut straight, rather than tapered, they'd be a lot weaker. The pipe would break off a lot easier.
Contrary to my own belief, I don't know everything... but I have never seen straight thread on RMC.
IMO the straight thread being weaker isn't much of an issue. If you cut a running thread the entire piece of conduit with the exception of the last inch or so is a straight thread.
mattsilkwood
Senior Member
- Location
- missouri
our threader has a block you flip to change from tapered to straight threads. i thought most threaders have this. im talking about big threaders not a power pony
M. D. said:
The question in the OP "Are the threads on rigid conduit threaded??? I believe so but some controversy!"
Well as I see it this "thread" is on "rigid conduit", So is this thread, threaded ? :grin: I know it's a controversy.
- Location
- Illinois
- Occupation
- retired electrician
I think that main reason that conduit is required to have tapered threads is the fact that they will result in better physical contact and therefore make a better electrical connection to the couplings or other fittings. There also may be an issue with physical strength. I believe the strength issue is the reason for the code rule that prohibits the use of running threads at a coupling.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
don_resqcapt19 said:
I agree with the strength issue with running threads at couplings. But for entries into boxes IMO the difference between the two types of threads isn't significant. I would question however why a tapered thread going into a straight threaded coupling would have any measurable increase in physical contact between the raceway and the coupling? Mating two tapers together when the raceway and the coupling are both tapered would IMO have a measurable difference in contact.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
realolman said:
Sorry for the confusion. :grin:
The thread on the pipe is required to be tapered. The thread on a rigid coupling is straight. So when inserting the tapered pipe thread into the straight coupling IMO there isn't much of a mechanical difference if both threads were straight or one was tapered and the other straight. Just comparing to two types of threads when connected to a coupling.
I'm afraid to reply, because it seems someone is going to pop out of the bushes with something that will make me look like a fool, but...
Wouldn't it be because at the beginning of the thread the outside diameter of the pipe's thread is smaller than the inside diameter of the coupling, and if the male thread was straight it would never get any tighter... but the tapered thread's OD would continue to get larger until it wouldn't fit into the coupling any more? At that point it would be, IMO, tighter than the running threads.
Also, at that point, the wall of the conduit itself would be thicker because of the lighter cut of the threads, which seems to me would be less likely to break.
Wouldn't it be because at the beginning of the thread the outside diameter of the pipe's thread is smaller than the inside diameter of the coupling, and if the male thread was straight it would never get any tighter... but the tapered thread's OD would continue to get larger until it wouldn't fit into the coupling any more? At that point it would be, IMO, tighter than the running threads.
Also, at that point, the wall of the conduit itself would be thicker because of the lighter cut of the threads, which seems to me would be less likely to break.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Smart $ said:
Yes that's what I was trying to say. If you make a 10" running thread you'll have about 9" of straight thread where the die will have passed completely over the conduit. The last inch or so will be tapered.
TOOL_5150
Senior Member
- Location
- bay area, ca
Which is why its so easy to get a locknut on all-thread.
~Matt
~Matt
dcspector
Senior Member
- Location
- Burke, Virginia
realolman said:
I would not worry about it ........we can't see each other and probably never will....so no big deal and who cares. this Forum is all about education and not one person on this Forum knows it all.
- Location
- Illinois
- Occupation
- retired electrician
Rob,infinity said:
There is still a taper on the male thread and that provides a "wedge" fit to the straight thread coupling and provides a better connection. The required taper of 3/4" per foot will provide an increase in the diameter of about 1/16" over the length of a 3/4" conduit thread. How can that not be a better connection than a thread that provides no increase in diameter?
- Location
- New Jersey
- Occupation
- Journeyman Electrician
don_resqcapt19 said:
It's just my opinion but the 1/16" is somewhat negligible because even with a straight thread there is still a portion at the end of the thread that it not cut to the full depth of the straight thread and is in affect tapered. After factoring in all of that, in IMO with 3/4" of thread there isn't much of a difference between a tapered thread and a straight thread going into a straight coupling.
Is there an actual difference? Yes, I agree with you that there is but IMO from a practical standpoint the amount of difference isn't really an issue if they're both made up wrench tight.
ultramegabob
Senior Member
- Location
- Indiana
infinity said:
NSPL threads are specifically for the use of locknuts, that is what the L stands for. http://www.thepipefittings.com/pipe-threads.html
- Status