Conduit threads

[Biggshaheed]

What is the minumum amount of thread can be exposed on conduit. Once read 7 threads in fitting and 4 maximum left exposed. What is the answer and where is it in the NEC

 

[infinity]

Other than being required to be tapered for standard conduit installation I don't beleive that you won't find any minimum/maximum.. You can use running thread if you so choose. There are some thread requirements in hazardous locations like the minimum of 5 threads engaged such as in 500.8(E)(1).

 

[acrwc10]

I see running thread run all the time by solar installers.

 

[tom baker]

The 7/4 maybe a job spec. Without someone watching you assemble, how would you determine 7 threads?

 

[don_resqcapt19]

The total number of threads is based on the NPT standard. A full thread on 3/4" conduit is approximately 3/4" long with 10 threads. You should be able to hand thread so there are 3 to 4 threads showing. Electrical equipment should be made up wrench tight so would expect to see no more than 2 threads showing. This is based on the ANSI/ASME B1.20.1 pipe thread standard which is the required thread system for threaded conduit.

 

[tom baker]

The total number of threads is based on the NPT standard. A full thread on 3/4" conduit is approximately 3/4" long with 10 threads. You should be able to hand thread so there are 3 to 4 threads showing. Electrical equipment should be made up wrench tight so would expect to see no more than 2 threads showing. This is based on the ANSI/ASME B1.20.1 pipe thread standard which is the required thread system for threaded conduit.

Thanks Don, that’s where the 7/4 came from. As much rigid as I have threaded, I never knew about how many full threads there would be. Going into a box, I would measure to the face and add 5/8”

 

[don_resqcapt19]

Thanks Don, that’s where the 7/4 came from. As much rigid as I have threaded, I never knew about how many full threads there would be. Going into a box, I would measure to the face and add 5/8”

The problem I have seen many times is the about of galvanizing in the female threads on some conduit bodies and having to see the die for a deeper cut to get a sufficient number of threads screwed into the conduit body. This varied from batch to batch of conduit bodies, so we kept changing the thread depth based on the conduit bodies we were using at that time.

 

[coffeebean]

342.42(B) Running Threads shall not be used on conduit for connection at couplings

 

[infinity]

342.42(B) Running Threads shall not be used on conduit for connection at couplings

True but what are you getting at? Running threads are permitted for use with locknuts and other fittings.