Pvc into top of nema 3 enclosure

[mtnelect]

I got two PL due for review on September 7. I think I will write two more; one to outlawing rigid use underground, one mandating PVC use only underground. I can't count how many times I have found rigid rusted out completely underground. Plus, when you use PVC, you have to pull a green grounding wire. That will reduce the impedance and make it a better installation.

 

[augie47]

Looking at the makeup of CMP8, I doubt that proposal will get very far.

 

[infinity]

I think I will write two more; one to outlawing rigid use underground, one mandating PVC use only underground. I can't count how many times I have found rigid rusted out completely underground.

The NEC already has a provision for prohibiting RMC if there are corrosive conditions that would damage the raceway so anything new regarding underground installations will likely be rejected.

344.10(B)(1) Galvanized Steel, Stainless Steel, and Red Brass RMC, Elbows, Couplings, and Fittings.
Galvanized steel, stainless steel, and red brass RMC elbows, couplings, and fittings shall be permitted to be installed in concrete, in direct contact with the earth, or in areas subject to severe corrosive influences where protected by corrosion protection approved for the condition.

 

[JBHP]

The NEC already has a provision for prohibiting RMC if there are corrosive conditions that would damage the raceway so anything new regarding underground installations will likely be rejected.

Leave the Myers hub, insert a short metal nipple with one of these, then enter the PVC.

View attachment 2567163

Thanks for this response. Can you provide the ul listing for a pvc female adapter or guide to where I can find it.

 

[electrofelon]

. I can't count how many times I have found rigid rusted out completely underground.

I hear that a lot, but I have actually never seen it. Around here RMC seems to last a hundred years underground.

 

[don_resqcapt19]

Isnt it up to the manufacturer to get things listed? If contractors keep buying stuff for unlisted installations, why would any manufacturer voluntarily incur the testing costs?

True, but there has to be something in the standard to list and test to. As far as I know there is nothing in the standards relating to this that reference anything other than RMC, and often that does not even include IMC, even though the threads are identical.

 

[mtnelect]

SECTION 604
RIGID PLASTIC CONDUIT
604. 01 GENERAL. - The Contractor shall furnish and install rigid
plastic condwt, complete with fittings and appurtenances, where and as
shown on the plans or where required, including all Incidental Work
necessary or required for a complete, legal, and satisfactory installation.
All applicable requirements for rigid steel conduit and fittings and
the installation thereof shall apply . equally to rigid plastic conduit and
fittings.
Rigid plastic conduit and fittings shall be impervious to soil or
environmental chemicals, and that for use underground shall be designed
for direct burial and shall have a minimum wall thickness of 1/8 inch.
Only virgin materials shall be used in the manufacture of rigid plastic
conduit. Such conduit containing reclaimed materials will be rejected.
Rigid plastic conduit and fittings shall be designed for solvent-weld
joining.

Reference: State of California - Caltrans, Standard Plans & Specifications (Geen Book)

This is what they use now for Public Works - Traffic Signals.

 

[don_resqcapt19]

Thanks for this response. Can you provide the ul listing for a pvc female adapter or guide to where I can find it.

UL 651 is the standard that applies. You can register at UL to view it for free, using the same non-user friendly viewing system that the NFPA uses for free viewing of their codes.
Section 1.5.2 of that standard says:
Internally threaded adapters covered by these requirements are fittings intended for joining a length of rigid PVC conduit or a PVC elbow to threaded rigid metal conduit or other externally threaded devices.
1.5.3 says
Externally threaded adapters (also referred to as terminal adapters) covered by these requirements are fittings intended for joining a length of rigid PVC conduit or elbow to:
a) The knockout area of a metal box with a metal locknut
b) A threaded metal hub or fitting on a metal box
c) A threaded hub on a phenolic box, or
d) A knock out on a phenolic box.

Note that bold language is in conflict with the guide information for the conduit hub.
From the UL Guide Information for "Conduit Fittings (DWTT)

Fittings with internal female threads (e.g., hubs, conduit bodies, couplings) have only been investigated for use with threaded rigid conduit.

 

[infinity]

Thanks for this response. Can you provide the ul listing for a pvc female adapter or guide to where I can find it.

Here's a spec sheet from T&B. It has the UL listing standard on the sheet.

https://ideadigitalasset.com/DAMRoot/Original/10086/12055_10737571-SPE-EN-1.pdf

 

[JBHP]

Here's a spec sheet from T&B. It has the UL listing standard on the sheet.

https://ideadigitalasset.com/DAMRoot/Original/10086/12055_10737571-SPE-EN-1.pdf

Thanks infinity

 

[tortuga]

Seems like the old straight vs tapered thread issue, same reason you cant use EMT fittings on a bell box.
I wonder why they don't make a tapered thread male PVC adapter?

 

[don_resqcapt19]

Seems like the old straight vs tapered thread issue, same reason you cant use EMT fittings on a bell box.
I wonder why they don't make a tapered thread male PVC adapter?

Based on the information from UL 651 that I posted in post 28, I think that they are tapered thread.

 

[electrofelon]

Seems like the old straight vs tapered thread issue, same reason you cant use EMT fittings on a bell box.
I wonder why they don't make a tapered thread male PVC adapter?

Based on the information from UL 651 that I posted in post 28, I think that they are tapered thread.

This came up in a thread a bit ago where someone claimed TA's were tapered threads. I didn't believe them so I went out and measured them with my dial calipers, and indeed they are tapered, although it did seem to be a little less than national pipe taper

 

[jim dungar]

UL 651 is the standard that applies. You can register at UL to view it for free, using the same non-user friendly viewing system that the NFPA uses for free viewing of their codes.
Section 1.5.2 of that standard says:
Internally threaded adapters covered by these requirements are fittings intended for joining a length of rigid PVC conduit or a PVC elbow to threaded rigid metal conduit or other externally threaded devices.
1.5.3 says
Externally threaded adapters (also referred to as terminal adapters) covered by these requirements are fittings intended for joining a length of rigid PVC conduit or elbow to:
a) The knockout area of a metal box with a metal locknut
b) A threaded metal hub or fitting on a metal box
c) A threaded hub on a phenolic box, or
d) A knock out on a phenolic box.

Note that bold language is in conflict with the guide information for the conduit hub.
From the UL Guide Information for "Conduit Fittings (DWTT)

So the issue seems to be with the metal "hub" manufacturers and not the PVC TAs.

 

[electrofelon]

UL 651 is the standard that applies. You can register at UL to view it for free, using the same non-user friendly viewing system that the NFPA uses for free viewing of their codes.
Section 1.5.2 of that standard says:
Internally threaded adapters covered by these requirements are fittings intended for joining a length of rigid PVC conduit or a PVC elbow to threaded rigid metal conduit or other externally threaded devices.
1.5.3 says
Externally threaded adapters (also referred to as terminal adapters) covered by these requirements are fittings intended for joining a length of rigid PVC conduit or elbow to:
a) The knockout area of a metal box with a metal locknut
b) A threaded metal hub or fitting on a metal box
c) A threaded hub on a phenolic box, or
d) A knock out on a phenolic box.

Note that bold language is in conflict with the guide information for the conduit hub.
From the UL Guide Information for "Conduit Fittings (DWTT)

Maybe the OP can show this to the inspector to help gain some ground.

 

[don_resqcapt19]

So the issue seems to be with the metal "hub" manufacturers and not the PVC TAs.

I think just with the listing standard that does not specify testing with anything other than RMC.

 

[wwhitney]

I think just with the listing standard that does not specify testing with anything other than RMC.

But if you want to use Part A with Part B, is it necessary that the maker of Part A test it with Part B, and that the maker of Part B test it with Part A? Or does it suffice that just one of them tests the combination?

I would expect that one is enough, and that the listing of the PVC male adapter suffices for the arrangement in the OP.

Cheers, Wayne

 

[tortuga]

This came up in a thread a bit ago where someone claimed TA's were tapered threads. I didn't believe them so I went out and measured them with my dial calipers, and indeed they are tapered, although it did seem to be a little less than national pipe taper

Is only the male adapter tapered? Most females look straight to me but you never know.

 

[mtnelect]

Looking at the makeup of CMP8, I doubt that proposal will get very far.

I agree ... After doing some research, my PL would not pass muster. Soil conditions vary nationwide, so the NFPA had to come up with a generic section that could apply. In Southern California all the utilities are now using plastic.

 

[JBHP]

Problem is with the myers hub per its listing use its specified imc or rigid. Does not include PVC connectors. or at least fails to include them. Here is cut sheet for myers hub

https://assets.gordonelectricsupply.com/datasheets/ts/HALAXCC00003_46.pdf?_ga=2.178875620.1723738955.1693163593-831505412.1693163593&_gac=1.118935675.1693183114.Cj0KCQjw6KunBhDxARIsAKFUGs95uuXPueAd8G_tyAmnZ5i2DqeZzZepM7dfxEB54WYU_kzZCtJ1eAIaAmPDEALw_wcB