Threading PVC in the Field

[TX_Electrician]

Hi all,

I have a question, Is threading electrical PVC conduit (Sch 40 and/or Sch 80) in the field an approved/listed means for construction?

I personally have never seen this done in the field, nor would I thread PVC in the field. I am questioning if it is not allowed/not allowed per code or standard or if it is not threaded based on convenience or cost.

Thank you for your responses.

 

[JDBrown]

I'm no electrician, but the only method I've ever seen for adding threads to PVC was by gluing a threaded fitting onto the end. Are you talking about cutting threads into a PVC conduit?

 

[Bang]

Personally, never seen nor heard of this being done before.

 

[GoldDigger]

Personally, never seen nor heard of this being done before.

Likewise. And I was surprised to see a question here about whether PVC (electrical) with one bell end per length was standard or not....
But never threaded.
And I admit that I do not know whether the threaded PVC fittings use molded or cut threads. But the surface treatment on them seems to be different from straight tubing.

 

[jaylectricity]

I don't even see a usable purpose for doing so. I suppose if you had a way to do it and you were doing a job where you needed to land the PVC in a box, didn't have a male adapter and the closest supply house was an hour away. But that's a long-shot to carry any kind of threading device on the truck. Probably should just have male adapters for all the common pipe sizes.

 

[Dennis Alwon]

Short answer is you cannot thread pvc.

 

[Gregg Harris]

Short answer is you cannot thread pvc.

Schedule 80 and up can be threaded, but not 40.

When schedule 40 FPT or MPT are threaded they have a thicker interior mold.

 

[ptonsparky]

I think I even t!hreaded some of it way back when. Worked for a Heating/Plumbing/Electrical shop at the time and didn't know any better than to do what was asked.

 

[kwired]

I don't even see a usable purpose for doing so. I suppose if you had a way to do it and you were doing a job where you needed to land the PVC in a box, didn't have a male adapter and the closest supply house was an hour away. But that's a long-shot to carry any kind of threading device on the truck. Probably should just have male adapters for all the common pipe sizes.

If you have a pipe threader that you use on RMC or IMC you have a way to do it. I have threaded PVC before, very seldom though, and not always for use for electrical purposes either so it can be done.

Otherwise:

Short answer is you cannot thread pvc.

And not because it is physically impossible, but because NEC does not permit it.

There is no specific prohibition of it in art. 352, but at same time read 344.28 or 342.28 and then go to 352 and try to find anything similar that permits threading - it is not there.

 

[jusme123]

Hi all,

I have a question, Is threading electrical PVC conduit (Sch 40 and/or Sch 80) in the field an approved/listed means for construction?

I personally have never seen this done in the field, nor would I thread PVC in the field. I am questioning if it is not allowed/not allowed per code or standard or if it is not threaded based on convenience or cost.

Thank you for your responses.

are you sure your not talking about pvc coated rigid conduit?

 

[mjf]

I've never threaded PVC conduit.

I did encounter it one time when I was disassembling something or other. Said to my coworker "What the?, look at this, have you ever seen threaded PVC before?"

 

[Gregg Harris]

If you have a pipe threader that you use on RMC or IMC you have a way to do it. I have threaded PVC before, very seldom though, and not always for use for electrical purposes either so it can be done.

Otherwise:



And not because it is physically impossible, but because NEC does not permit it.

There is no specific prohibition of it in art. 352, but at same time read 344.28 or 342.28 and then go to 352 and try to find anything similar that permits threading - it is not there.

Just because it is not listed as a procedure does not mean that it is not permitted.

I doubt seriously that anyone has thought of proposing it because the chances of it being inplemented in the field is to infrequent to merit.

352.48 Joints. All joints between lengths of conduit, and between conduit and couplings, fittings, and boxes, shall be made by an approved method.

A threaded joint is an approved method of joining.

 

[kwired]

Just because it is not listed as a procedure does not mean that it is not permitted.

I doubt seriously that anyone has thought of proposing it because the chances of it being inplemented in the field is to infrequent to merit.

352.48 Joints. All joints between lengths of conduit, and between conduit and couplings, fittings, and boxes, shall be made by an approved method.

A threaded joint is an approved method of joining.

Having done it before I will say that unless you have good sharp dies in the threader, it does not thread all that easily without the fear of possibly snapping off the pipe in the threader. The colder the pipe is the easier it threads IIRC. I also kind of wonder just how strong the pipe wall is where it has been threaded - except for sch 80. I do feel that threaded sch 80 is possibly less likely to break than standard male adapters are though.

 

[jaylectricity]

I've learned from people on this site that the code is permissive. If it doesn't say you can't do it, you can do it.

 

[GoldDigger]

I've learned from people on this site that the code is permissive. If it doesn't say you can't do it, you can do it.

Possibly most importantly, it does not say that you cannot make a d***ed fool of yourself as long as the result is safe.

 

[ActionDave]

ATS for a cell tower back up generator taught me otherwise

ATS for a cell tower back up generator taught me otherwise

Short answer is you cannot thread pvc.

When you are on the top of a mountain, three hour drive from civilization, twice that one way to get somewhere that might have what you need, and are short of fittings, and those missing fittings are the only thing keeping you from getting the job done so you can go home you bet you can!

 

[goldstar]

When you are on the top of a mountain, three hour drive from civilization, twice that one way to get somewhere that might have what you need, and are short of fittings, and those missing fittings are the only thing keeping you from getting the job done so you can go home you bet you can!

I guess that's about the only scenario I could think of as to why anyone would thread PVC. But as long as we're making up scenarios you also have to ask the question "If you didn't have a female adapter on the truck why would you have the pipe threader on the truck"?

 

[kwired]

I guess that's about the only scenario I could think of as to why anyone would thread PVC. But as long as we're making up scenarios you also have to ask the question "If you didn't have a female adapter on the truck why would you have the pipe threader on the truck"?

Welcome to my world I seem to always have everything but that one 50 cent fitting needed on the truck.

 

[TX_Electrician]

I am only talking about PVC. I have a young coworker that wanted to specify threading PVC in the field and I assured him it is not an acceptable means for installation. He has found threading tools online. Based on my experience I have never seen PVC threaded in the field and have not heard of anyone else doing it, except for those on this forum.

My problem arose when I was researching justification for why it should not be threaded in the field. Except for those articles mentioned by another (342 and 344) I cannot find anything prohibiting it. I have called a PVC manufacturer and they referred me to the local inspectors. I have contacted local electrical inspectors but have not heard back from them yet.

I appreciate everyone's responses!

 

[junkhound]

three hour drive from civilization


Yep, been there.
If need be, you will find that you can cut 5 threads into PVC pretty quickly with a file if you need to.