Threading PVC in the Field

[growler]

I am only talking about PVC.
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.

I doubt the manufacturers of PVC conduit have ever tested their product to be threaded in the field. They do sell all the fittings necessary for the installation of PVC conduit.


So I would think that you are in a gray area. If an inspector were to reject a job based on the fact that the PVC was threaded then you would have little to fall back on.

 

[Gregg Harris]

I doubt the manufacturers of PVC conduit have ever tested their product to be threaded in the field. They do sell all the fittings necessary for the installation of PVC conduit.


So I would think that you are in a gray area. If an inspector were to reject a job based on the fact that the PVC was threaded then you would have little to fall back on.

Schedule 80 is approved by the manufacturers to be threaded in the field, rarely is it done but nothing prohibits it.

 

[ptonsparky]

As with a lot of things, just because you can, doesn't mean you should.

 

[mjf]

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

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

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.

Schedule 80 is approved by the manufacturers to be threaded in the field, rarely is it done but nothing prohibits it.

Ever get the feeling nobody hears a thing you say???

 

[JDBrown]

Schedule 80 is approved by the manufacturers to be threaded in the field, rarely is it done but nothing prohibits it.

If it's approved by the manufacturer, it should be fine. If not, it may be a violation of 110.3.

 

[Gregg Harris]

Ever get the feeling nobody hears a thing you say???

perhaps I should type in caps.

 

[ActionDave]

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.

Dude! You are the electrical Survivor Man.

 

[renosteinke]

Technically? Sure. PVC threads real nice. Now, what are you going to connect it to? I don't see any threaded fittings out there. Entering a box? You still get to use a plastic bushing and two locknuts.

 

[GoldDigger]

Technically? Sure. PVC threads real nice. Now, what are you going to connect it to? I don't see any threaded fittings out there. Entering a box? You still get to use a plastic bushing and two locknuts.

You fasten two lengths of PVC together with a female threaded adapter because you forgot to bring your cement with you.

 

[RLyons]

You fasten two lengths of PVC together with a female threaded adapter because you forgot to bring your cement with you.

Am I missing something??? I thought a FA was glue in on one side thread on the other? :?

 

[John120/240]

Am I missing something??? I thought a FA was glue in on one side thread on the other? :?

What I imagine: PVC thread in to FA, short piece of plain PVC between two FA, then threaded PVC out from FA

 

[GoldDigger]

Am I missing something??? I thought a FA was glue in on one side thread on the other? :?

OK. Coupling, not adapter.

 

[hawkeye23]

Ridget make dies for pvc . The maintenance shop I've been in has a set of dies for pvc. When or why they use it I don't know . I have seen many treaded fittings made of pvc so I would thing someone needs pipe to go along with them. I am sure it it is only for plumbing.

 

[mjf]

IIRC the one time I saw threaded PVC it was 2" and threaded into a rigid coupling.

 

[Dennis Alwon]

Here is an excerpt from schedule 80 specs which can be found here

Thread only Schedule 80 or heavier walls. Threading requires a 50% reduction in pressure rating stated for plain end pipe @73F.Threading of Schedule 40 PVC pipe is not a recommended practice due to insufficient wall thickness.

Somehow this seems to imply it is okay but it weakens the pipe so is that compliant for the NEC????? IDK

 

[kwired]

Here is an excerpt from schedule 80 specs which can be found here



Somehow this seems to imply it is okay but it weakens the pipe so is that compliant for the NEC????? IDK

Those specs are for "pressure rated pipe" as noted in that document.

Pipe used for electrical doesn't (normally) have to withstand pressure. Pipe rated for electrical probably is not tested for pressure characteristics.

The cellular core pipe rated for DWV only, I can almost assure you would be a disaster to try to thread.