Rigid galvanized coupling to liquid tight flex connections

ramsy said:
Female threads never require taper, only male nipples.

Visualize a tap & die set, the tap is always straight, only the die is tapered.

UL category for conduit fittings is (DWTT), which allows sealing locknuts.
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UL 914(B) permits the female threads to be either tapered or straight. The female threads for most conduit bodies are tapered. The only electrical female thread that is required to have straight threads are threaded couplings for rigid and IMC.
 
electrofelon said:
Ya know every hardware store has NPT taps..... Go to McMaster-Carr and you can have whatever size npt tap you want tomorrow.
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Yes I see, with my head buried up residential, the endless fascination with BS leaves me amazed by missing NPT.
 
don_resqcapt19 said:
UL 914(B) permits the female threads to be either tapered or straight. The female threads for most conduit bodies are tapered. The only electrical female thread that is required to have straight threads are threaded couplings for rigid and IMC.
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Thanks for clarifying that.

Do I understand correctly that tapered nipples in straight RMC couplings are approved?

Do I understand correctly that straight threads, typical of connector fittings, in tapered bodies are not approved, and neither are straight-straight unions in wet locations without sealing o-ring / locknuts?
 
infinity said:
The issue is the straight threads on the connector. It's a listing issue which IMO is bogus given that there is no readily available fitting to transition from one to the other wiring method.
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It's been done for ever. I don't know what the big deal is. They should get rid of any restriction against its use.

I was always told when joining RMC that the two pipes were supposed to meet in the middle and that the joint is not necessarly water tight. Thats why we use conductors with a "W". Any pipe in a wet location will have moisture and water even if just from condensation. You do your best to keep it out but it won't be 100%. I don't see the difference between RMC & a fitting screwed into a coupling
 
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ramsy said:
Thanks for clarifying that.

Do I understand correctly that tapered nipples in straight RMC couplings are approved?

Do I understand correctly that straight threads, typical of connector fittings, in tapered bodies are not approved, and neither are straight-straight unions in wet locations without sealing o-ring / locknuts?
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1) The male threads for IMC and RMC are required to be tapered and the threads for the couplings are required to be straight, so yes the combination is approved as it is the only possible combination.

2) Correct, they are not approved, but only because they have not been evaluated for that use. (I have no idea of what you mean by a straight thread union)
 
don_resqcapt19 said:
1) The male threads for IMC and RMC are required to be tapered and the threads for the couplings are required to be straight, so yes the combination is approved as it is the only possible combination.

2) Correct, they are not approved, but only because they have not been evaluated for that use. (I have no idea of what you mean by a straight thread union)
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Excellent. Thank you

My last assumption was straight thread connector fittings are approved for RMC couplings in wet locations, only with sealing o-ring / locknuts?
 
ramsy said:
Couldn’t imagine female threads with taper, except perhaps molded PVC boxes, but your article shows it with metallic hubs.
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Many myers hubs, meter socket hubs or other similar bolt on hubs have tapered female threads. It's the reason many straight thread fittings don't thread in as far as one would expect, they "bottom out" in the taper of the hub but RMC threads in just fine.
 
ramsy said:
Excellent. Thank you

My last assumption was straight thread connector fittings are approved for RMC couplings in wet locations, only with sealing o-ring / locknuts?
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I do not understand what you are asking. I see no way to thread a connector into a coupling and use a sealing locknut to make a seal. Sealing locknut are for use with entries into enclosures.
 
don_resqcapt19 said:
UL 914(B) permits the female threads to be either tapered or straight. The female threads for most conduit bodies are tapered. The only electrical female thread that is required to have straight threads are threaded couplings for rigid and IMC.
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So if the threads on GRC conduit are tapered NPT and the threads on the GRC couplings are straight, isn’t this the same scenario with the tapered LFMC connections to straight couplings?


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Isaiah said:
the tapered LFMC connections to straight couplings
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Do you have an LFMC fitting with tapered male threads on it? Then you can use it with a straight coupling.

But most "connectors" for EMT, LFMC, etc use straight threads and are only for connecting to a hole in sheet material, not female threads.

Cheers, Wayne
 
wwhitney said:
Do you have an LFMC fitting with tapered male threads on it? Then you can use it with a straight coupling.

But most "connectors" for EMT, LFMC, etc use straight threads and are only for connecting to a hole in sheet material, not female threads.

Cheers, Wayne
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Theyre using standard Appleton ST or STB LFMC connectors which have tapered NPT threads...
They attach directly to LB and T condulets but in many instances they also attach directly to GRC couplings for connections to motors and other devices where vibration may occur


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Isaiah said:
Theyre using standard Appleton ST or STB LFMC connectors which have tapered NPT threads...
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Those certainly don't appear to have tapered NPT male threads. The catalog description is "Standard Liquidtight connector. Use with LFMC in heavy commercial and industrial applications." Whereas the fitting STF can be used with a rigid nipple: "Female hub threads directly to conduit threads. Transition from RMC/IMC to LFMC in heavy commercial and industrial applications."

Basically, if it comes with a locknut on it, it's for use with that locknut to connect to an enclosure. "Connector" = connect to an enclosure only. If it has tapered female threads on it, the box will say something like "for use with threaded hubs" and IIRC it won't come with a locknut on it.

Cheers, Wayne
 
wwhitney said:
Those certainly don't appear to have tapered NPT male threads. The catalog description is "Standard Liquidtight connector. Use with LFMC in heavy commercial and industrial applications." Whereas the fitting STF can be used with a rigid nipple: "Female hub threads directly to conduit threads. Transition from RMC/IMC to LFMC in heavy commercial and industrial applications."

Basically, if it comes with a locknut on it, it's for use with that locknut to connect to an enclosure. "Connector" = connect to an enclosure only. If it has tapered female threads on it, the box will say something like "for use with threaded hubs" and IIRC it won't come with a locknut on it.

Cheers, Wayne
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View attachment catalog-liquidtight-st-stb-insulated-throat-connectors-appleton-en-7436600.pdf
They are using ST and STB fittings it shows as having tapered NPT


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don_resqcapt19 said:
I do not understand what you are asking. I see no way to thread a connector into a coupling and use a sealing locknut to make a seal. Sealing locknut are for use with entries into enclosures.
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See picture with O-Ring, or sealing locknut, for wet location approval.
 

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