Fittings into Hubs

[infinity]

Has anyone read this story in Electrical Contractor Magazine? Mark Ode from the UL addresses using EMT connectors (et al.) into the tapered threads of a hub. His opinions are disturbing to say the least since it would violate 99% of all of the services around here not to mention millions of other installations.

http://www.ecmag.com/index.cfm?fa=article&articleID=11585

 

[iwire]

It seems they should start testing / listing for applications that are commonly accepted so we can go on as we have been. :roll:

 

[Dennis Alwon]

This has come up before in relation to PVC connectors in a hub. Also, I believe Don, brought up the fact that a sealing locknut was not approved for pvc threads. From the UL book

Sealing (Liquid-tight) Locknuts ? Sealing locknuts are intended for use with threaded rigid metal conduit and intermediate metal conduit with one sealing locknut in the outside or the inside and either an ordinary locknut or sealing locknut on the inside of the enclosure for wet locations or liquid-tight applications. Sealing locknuts may also be used with Listed wet location or liquid-tight fittings where so marked on the fitting carton and used on the inside of the enclosure.

So far this year I have learned that the emt compression fittings I have been using for years are not rated for RT application.Fortunately I don't use emt outdoors very often.
Then I learned about the sealing locknuts which I have used with PVC-- I still don't know why they won't work although I understand that the are not listed for that use.

Now we learn that emt. pnc etc fittings cannot be used in hubs. What's next.​

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[infinity]

If UL wants to rewrite the way we install things then they should make an effort to cover all of the bases. I can see someone reading this article and then violating every service that doesn't have RMC or IMC threaded into the meter hub.

 

[Eagle126]

Can you tell me why every service i have installed using pvc connectors into hubs to date in many cities around boston have been passed with no problem?

 

[iwire]

The use of commonsense.

 

[Dennis Alwon]

Can you tell me why every service i have installed using pvc connectors into hubs to date in many cities around boston have been passed with no problem?

Sure--- because most inspectors don't use the UL book and there is nothing in the NEC that prohibits it.

 

[don_resqcapt19]

Sure--- because most inspectors don't use the UL book and there is nothing in the NEC that prohibits it.

Other than 110.3(B)

 

[stevenje]

If they are concerned with the mismatch of the thread tampers shouldn't they be concerned with the locknuts? Are there two different types of locknuts? Is there one that is used on tampered threads and another used on straight threads? How about couplings or reducer bushings or any other threaded fitting? Can you say "Can of Worms"?

 

[paul]

This has come up before in relation to PVC connectors in a hub. Also, I believe Don, brought up the fact that a sealing locknut was not approved for pvc threads. From the UL book

So far this year I have learned that the emt compression fittings I have been using for years are not rated for RT application.Fortunately I don't use emt outdoors very often.
Then I learned about the sealing locknuts which I have used with PVC-- I still don't know why they won't work although I understand that the are not listed for that use.

Now we learn that emt. pnc etc fittings cannot be used in hubs. What's next.​

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What about sealing washers? I prefer T&B Sureseals over sealing locknuts.

 

[nhfire77]

Quote from the article:

"Care must be taken to install electrical components in accordance with the NEC, so do not use an EMT fitting with a hub, a boss or a conduit body"

OK, I will stop using EMT fittings in hubs etc. if you (Mark Ode) won't write boneheaded articles referencing something that no one recognizes as a problem.

 

[Dennis Alwon]

What about sealing washers? I prefer T&B Sureseals over sealing locknuts.

Paul, I don't know what to say. I have never seen them and they are not listed as sealing washers in UL book.

Carlon has these and it states:

Where a waterproof termination is required into any enclosure, metallic or non-metallic, install the neoprene washer over the threads of a terminal adapter before inserting into the enclosure.

 

[Dennis Alwon]

I just found this based on the washer shown above.

To Whom IT May Concern:
Controlled Substances Declaration
Thomas & Betts Corporation Products​

This is to certify that Thomas & Betts (T&B) product:​

E943JW​

is compliant with the European Directive 2002/95/EC (RoHS) or its exemption(s).
It is further declared that based on the reasonable inquiry and current information
received from the product manufacturing plants and the suppliers of the raw materials
used in the above listed products, this certification is true, accurate and complete
at the date of this issue.​

Om Chopra
Corporate Director of Enviromental Affairs
Thomas & Betts Corporation
8155 T&B Boulevard
Memphis, TN 38125
United States of America
Tel: 901-252-5937
Fax: 901-252-1340​

om_chopra@TNB.com

 

[Dennis Alwon]

What about sealing washers? I prefer T&B Sureseals over sealing locknuts.

Same problem Paul. This is from T&B

3/4" Sealing Ring, Santoprene thermoplastic rubber with stainless steel retainer. For use with Rigid/IMC Conduit

 

[paul]

Same problem Paul. This is from T&B

Maybe so, but they beat the o-rings in that the metal ring on the outside does not allow it to squish out and away from the fitting. My first run in with these was installing some phone equipment where the supplier sent out fittings with the equipment. Seen them, noted their number and have ordered them in the past.

Again, it's a way better product then the goofy o-rings or rubber washers on the EMT RT fittings.

If we were go go by the book, I would never be allowed to use an LB on EMT raceway. Nor would I be allowed to use a coupling to transition from EMT to flex or rigid. BTW, what is the thread pitch on a rigid threadless fitting? Can you use these without a locknut? What sort of fitting are we allowed to thread into a PVC FA? For that matter, rigid threaded couplings are straight cut threads. Why is this okay and not the reverse? Common sense has to come into play sometime or another.

This subject rears it's ugly head from time to time.

 

[Dennis Alwon]

Common sense has to come into play sometime or another. This subject rears it's ugly head from time to time.

When does common sense come into play? There are some inspectors, as well as electricians, who will use common sense, others who go by the book and yet others who are clueless. I just pass on the info- you do what you want with it.

BTW, there must be some obscure reason why these locknuts and washers are not listed for emt or pvc. When I have used them I can't imagine how they would leak but what do I know. :grin:

 

[shepelec]

I guess I can never run emt outside because I have never seen any conduit body with a built in compression fitting.

And since when does thread pitch seal out water?

Sounds like a typical case of over analyzing something that is not an issue.:roll:

 

[don_resqcapt19]

I guess I can never run emt outside because I have never seen any conduit body with a built in compression fitting.

I have seen some, but not recently.

And since when does thread pitch seal out water?

The pitch (threads per inch) is the the issue. The issue is straight and taper threads. Threaded conduit and the fittings and hubs designed to be used with threaded conduit are both tapered threads. The EMT and other connectors have straight threads. It is UL's position that you can get a water seal or an adequate grounding path when you use a male straight thread with a female tapered thread, but note this is from the same company that says reducing washers provide an adequate grounding path!!! Also they don't seem to have any issue with the combination of tapered male threads and straight female threads. (the combination you get any time you use rigid or IMC with rigid or IMC couplings)

Sounds like a typical case of over analyzing something that is not an issue.:roll:

Exactly.