Unlisted NPT Couplings

[Wire-Smith]

cop-r-shield or led-plate will get you where you want to go with straight GRC couplings.
straight couplings are used both in vinyl coated rigid, and are listed for classified locations.

what do you need to be more resilient than explosion proof joints?
asking for a friend....

They are not explosionproof joints, that's why your not allowed npsm couplings between seal and enclosure or boundary but you are allowed fnpt fittings, code explicitly calls for fnpt there

 

[Wire-Smith]

in other words, do not over think it, its not the space shuttle. I have demo'd explosion proof raceways with enough water in it to flood the trench. especially for surface run (not buried), its going to condensate. when I started in San Fran, heck, we were drilling holes in some conduit bodies for the heavy fog... funny thing about over thinking stuff, just to discover that a plumber stuck a empty Gatorade bottle and his lunch trash in a stick of 3'' while eating lunch by the trailer...

If you seal the conduit you will not get condensation and I don't mean normal explosionproof seal, that won't do. This was all covered thoroughly earlier in this thread.
In other words, don't UNDER think it

 

[Wire-Smith]

i think it's extreme pressure anti sieze, but not postitive.
the kote is for drill pipe, i think.

led plate and cop r plate are about the same effectiveness, just one
is for conductivity, and better thermal transfer. the copper is what
i always ended up with in steam plants, and powerhouses.

not to beat a dead pipe coupling, but if you are using tapered couplings,
you will have several threads exposed that won't make up. bare threads
are the first point of corrosion and failure. if you use a straight GRC coupling,
all the threads will be buried inside the coupling, and if you use cop r plate or
whatever flavor you prefer, the threads will be full of the product, and no air,
or moisture will get to them.

and as long as we are on the subject, the absolute best product i've found for
penetrating rust and corrosion breaking, is aero kroil. nothing else even comes close.

Your threads will be exposed on the inside of the coupling, ask the guy that posted after your post. Also just screw a coupling on a pipe several threads and you can still move it back and forth like a swivel, the threads are not tight at all, only one small spot on npsm coupling is tight when joint is done, it would take something like tar to seal those threads. Also, you will see if you read the thread that the larger motivation is lower contact resistance. Also, exposed threads are supposed to be coated as good as the conduit coating is.

 

[Wire-Smith]

64 posts on a coupling and I only asked if as an inspector, would you fail it? And I think I only got three answers to that, thank you Infinty, Kwired and Roger

 

[rambojoe]

i dont need to think about it period. ill leave that to the engineer- or the lab... but I hate to say, condensation will happen. unless maybe you are on a star.

 

[Fulthrotl]

Your threads will be exposed on the inside of the coupling, ask the guy that posted after your post. Also just screw a coupling on a pipe several threads and you can still move it back and forth like a swivel, the threads are not tight at all, only one small spot on npsm coupling is tight when joint is done, it would take something like tar to seal those threads. Also, you will see if you read the thread that the larger motivation is lower contact resistance. Also, exposed threads are supposed to be coated as good as the conduit coating is.

as you pointed out, you were only looking for replies from inspectors.
as i'm not an agent for an AHJ, i'll stop now. good luck with your work.

 

[Gary11734]

Would any of you inspectors fail me for using hot dipped galvanized NPT plumbing pipe couplings with galvanized rigid conduit? I cannot find NPT conduit couplings(normal ones are NPSM (straight thread), if you know of any or have an idea of where i could get them please let me know. i know i could get a ul field evaluation, i think that is a waste, the couplings are ul listed for plumbing pipe, i know i could even get them listed for the use, just think that is a waste. And for the ones asking, i am using these for improved electrical connection at the joints and for water tight conduit, don't worry about telling me its a waste of time, you would be wasting your typing.

Thank you,

I remember when they said a steel 1900 box had to have a UL label. I'm like, it's a steel box!

If you have to ask, then I would fail you for knowing you shouldn't do it but just checking. It says, "plumbing pipe couplings". Are you plumbing or electrical work? I would never hesitate using this but knowing it probably would fail an inspection, I would find the right parts. We can debate until the cows come home on whether it's OK or not.

 

[don_resqcapt19]

I remember when they said a steel 1900 box had to have a UL label. I'm like, it's a steel box!
....

The NEC does not require a 1900 box to be a listed product.

 

[Gary11734]

The NEC does not require a 1900 box to be a listed product.

Tell that to Dade County School Tradesmen. Yeah, I know. Then they have you jumping through hoops to show them they have no clue in the first place...

 

[K8MHZ]

Tell that to Dade County School Tradesmen. Yeah, I know. Then they have you jumping through hoops to show them they have no clue in the first place...

Is this where the toaster question came from? :angel:

 

[Wire-Smith]

I remember when they said a steel 1900 box had to have a UL label. I'm like, it's a steel box!

If you have to ask, then I would fail you for knowing you shouldn't do it but just checking. It says, "plumbing pipe couplings". Are you plumbing or electrical work? I would never hesitate using this but knowing it probably would fail an inspection, I would find the right parts. We can debate until the cows come home on whether it's OK or not.

I wouldn't ask the inspector if i was going to do it, and they would never notice. I'm just asking, specifically the forum users as an inspector if they knew about it, would you fail it or pass it. I know 100% it is a code violation, but i am also very confident it is a better installation. It's an odd circumstance in which i can't think of any other electrical code circumstance that would be similar.

 

[ptonsparky]

I wouldn't ask the inspector if i was going to do it, and they would never notice. I'm just asking, specifically the forum users as an inspector if they knew about it, would you fail it or pass it. I know 100% it is a code violation, but i am also very confident it is a better installation. It's an odd circumstance in which i can't think of any other electrical code circumstance that would be similar.

Why would you ask an inspector to pass something that you know is 100% violation? Even rhetorically, it’s a fail.

 

[Wire-Smith]

Why would you ask an inspector to pass something that you know is 100% violation? Even rhetorically, it’s a fail.

like i said, i wouldn't ask anyone to pass it, and because it's a better install.

this is a photo of an installation that appears completely code compliant and clean install, the OCPD did not open on its own. The rigid was melting. it doesn't take much current to melt steel, or ignite combustibles (far less than your OCPD setting), so you want high enough current for your OCPD to operate, so the lower impedance on the circuit the better your chances.


View attachment 21987
and these are some tables from the following link but it is also in the IAEI and Soares books on maximum length for GRC for enough ground fault current
https://steeltubeinstitute.org/steel-conduit/wp-content/uploads/sites/4/2014/12/GROUNDIN.pdf


here's an excerpt from the linked study

The maximum allowable length for a specific system depends on conductor size, steel conduit size and fault type. In many cases,

the maximum allowable length for a phase to neutral fault is shorter than the maximum allowable length for a phase to steel conduit fault. Thus in most cases the steel conduit is not the limiting factor. In these cases, use of a supplemental grounding conductor will not increase the maximum allowable length. We recommend the use of the validated computer model to compute the maximum allowable length in specific systems.

now before someone says they would increase the size of the wire EGC, i know, that's not getting to the point. my point is
1.the conduit is an awesome EGC
2.lower contact resistance in the joints (the highest resistance parts of the system) would make this even better, i'm not sure how much better but i'm thinking under really high fault currents say like a huge parallel feeder and there is a ground fault in a conduit in the middle of a long run that it could prove to be substantially better.

NEC 2017 250.4(A)(5) Effective Ground-Fault Current Path. Electrical equipment and wiring and other electrically conductive material likely to become energized shall be installed in a manner that creates a low-impedance circuit facilitating the operation of the overcurrent device or ground detector for high-impedance grounded systems. It shall be capable of safely carrying the maximum ground-fault current likely to be imposed on it from any point on the wiring system where a ground fault may occur

so if you had a run double the length of the chart above, how would you be satisfying this code requirement for the very middle section of conduit? i know this long of a run isn't extremely common, but it is done. i have been on runs of 2,500'. and like i said before i don't know the difference this fnpt would make but it could be considerable and i think it would also offer more longevity to the install as well. looking at the study in the link, on the 1/2" emt the current had almost a 10% difference between steel and zinc couplings of the same style. again, there are plenty of tests i could and would do before doing this and even look into getting it listed, i originally just posted for an answer to the simple question

 

[don_resqcapt19]

... there are plenty of tests i could and would do before doing this and even look into getting it listed,...

You would first have to get the product standard changed....it specifies straight thread couplings. No matter what the testing shows, a tapered thread coupling could not be listed under the current product standard.

 

[Wire-Smith]

You would first have to get the product standard changed....it specifies straight thread couplings. No matter what the testing shows, a tapered thread coupling could not be listed under the current product standard.

are you refering to 6.7.5 "couplings shall be straight tapped." ? i take that to mean the threads on each end need to be aligned, but i'm not sure. Either way, i think the standard would be easy to change if the coupling passed the testing required for listing.

do you happen to have access to the UL testing requirements? ANSI requires a lot less than i expected.

 

[Wire-Smith]

interesting related find, merchant couplings are not listed as couplings like the ones that fall under fittings, they fall in with the conduit for listing.

[FONT=&quot]In the Scope and Listing Requirements sections the phrase “associated fitting” is used and is intended to refer to those nipple, elbows and couplings which are not made from Rigid Metal Conduit, Intermediate Metal Conduit or Electrical Metallic Tubing.[/FONT]

https://www.wheatland.com/wheatland...lbows-couplings-and-nipples-are-not-fittings/

 

[don_resqcapt19]

are you refering to 6.7.5 "couplings shall be straight tapped." ? i take that to mean the threads on each end need to be aligned, but i'm not sure. Either way, i think the standard would be easy to change if the coupling passed the testing required for listing.

do you happen to have access to the UL testing requirements? ANSI requires a lot less than i expected.

They is no way to even start to get a listing for a product that does not comply with the standard. The requirement that the couplings be "straight tapped" prohibits a taper tapped coupling.

The product standards are not public documents and are costly no matter who is the publisher of the standard. Product testing requirements are included in the product standard as far as I know. They are for sure in a standard that is published by UL.

 

[Wire-Smith]

They is no way to even start to get a listing for a product that does not comply with the standard. The requirement that the couplings be "straight tapped" prohibits a taper tapped coupling.

The product standards are not public documents and are costly no matter who is the publisher of the standard. Product testing requirements are included in the product standard as far as I know. They are for sure in a standard that is published by UL.

by product standard are you talking about ANSI C80.1? I guess i need to look into UL more but i thought they just had testing standards, that they make. I didn't think C80.1 would matter with a requirement like that, i thought UL made their own testing standards.


edit: looks like UL writes ANSI standards, so i would just need to submit a proposal to UL.

 

[don_resqcapt19]

by product standard are you talking about ANSI C80.1? I guess i need to look into UL more but i thought they just had testing standards, that they make. I didn't think C80.1 would matter with a requirement like that, i thought UL made their own testing standards.


edit: looks like UL writes ANSI standards, so i would just need to submit a proposal to UL.

Yes, UL is a major writer of ANSI standards and all of their standards that I have seen include the testing requirements. A very large portion of the standards used in the electrical industry are UL Standards, but any NRTL will test to the product standard no matter who wrote the standard.

The standards are consensus standards and anyone can submit a proposal for a change in the standard. UL has Standards Technical Panels, that work like the NEC Code Making Panels for processing of changes in the standard.

It appears that there are two product standards for rigid conduit, UL 6 published by UL and ANSI C80.1 published by NEMA. I did not realize that there were competing product standards. I have seen a number of dual published standards with the names of two accredited standard writing organizations on them but that does not appear to be the case here. I am not sure how that works.

Since they are both ANSI standards they both will have a way to submit proposals to change the requirements of the standard.

 

[Wire-Smith]

Yes, UL is a major writer of ANSI standards and all of their standards that I have seen include the testing requirements. A very large portion of the standards used in the electrical industry are UL Standards, but any NRTL will test to the product standard no matter who wrote the standard.

The standards are consensus standards and anyone can submit a proposal for a change in the standard. UL has Standards Technical Panels, that work like the NEC Code Making Panels for processing of changes in the standard.

It appears that there are two product standards for rigid conduit, UL 6 published by UL and ANSI C80.1 published by NEMA. I did not realize that there were competing product standards. I have seen a number of dual published standards with the names of two accredited standard writing organizations on them but that does not appear to be the case here. I am not sure how that works.

Since they are both ANSI standards they both will have a way to submit proposals to change the requirements of the standard.

Thanks,

next time i have a dlro and some spare time i will do some testing on the joints before i worry about working on a proposal. Do you have ANSI FB-1 for couplings? i cannot find free access to this. if you have it, is the testing even very extensive at all? i would guess just checking coating thickness, length and probably a compression test and maybe a go no go thread measurement.