RMC to FMC Transition

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gary b

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A RMC raceway is installed as the primary wire method to a transformer. At the transformer the installer transitions the RMC raceway to Flexible Metal Conduit without a ?C? condulet or a j-box. The FMC is attached to the RMC at the RMC threaded rigid coupling. Is this installation code compliant? If so, what reference?
 
There was a thousand (I'm exaggerating) post thread about this recently. Some opined that it was compliant, some said that it wasn't because the coupling wasn't listed for that use. IMO it's compliant. Besides they don't make transition fittings over 2" so you would need to use a coupling with a FMC connector for larger conduit transition. For what it's worth this method has been used for decades.
 
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I agree with Trevor this has been discuss before, and most agreed this was ok to do the connection this way. We have done this way forever, if not longer.
 
you need to watch out. this is not the same situation but about 2 years ago we were going from EMT to FMC for fixtures that were more than 6" from the box and the inspector said we needed to strap the flex within 12" of the change over because he saw it as being a termination point.
 
infinity said:
There was a thousand (I'm exaggerating) post thread about this recently.
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Improper Use of Fittings
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...and still going
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04-12-2007, 11:54 AM
 
Celtic,

Nice photo. I would be more concerned about the FMC coming out of that connector than the improper use of that coupling. Those connectors stink to say the least. Most of the old timers that I used to work with would put tie wire on them just to keep the flex in place.
 
That's Joe Todesco's pic from the thread.


I don't know if the connector or the FMC is to blame for the thing coming apart sometimes...but either way, a little tie wire goes a long way.
 
I would not have thought twice about doing what was in the picture. What exactly is the code issue here?......Thanks
 
celtic said:
Improper Use of Fittings
wrong.jpg


...and still going
Last posted to:
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04-12-2007, 11:54 AM
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I do this as does everyone else in the trade. What's the big deal? The emt connector is used properly on the emt. The flex connector is used properly on the flex. The rigid coupling is doing its job of connecting 2 threaded ends. Looks good to me. Hell if you to argue, are the threads of all the different connectors and fittings listed to be used only with listed items, like locknuts only or hubs only etc..? I don't think so. Take a threaded hub for example, you can thread all different types of connectors and pipe into it and theres no issue there. The rigid coupling is no different IMO.
 
celtic said:
Just follow the link:
Improper Use of Fittings
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I don't buy into that. If this practice wasn't allowed then it wouldn't be accepted by inspectors. Been doing this for years, been taught this method of transition and show the younger guys this method for that matter. Why try and argue to make our job more difficult than need be?
 
The entire argument against this type of installation stinks. The two fittings are installed wrench tight into the rigid coupling which some will argue is no good. Yet the FMC is held in place by two screws that tend to break the fitting if over tightened. I've seen many pieces of FMC come out of these type of fittings. I've never seen a wrench tightened RMC coupling come apart.
 
joe tedesco said:
http://forums.mikeholt.com/showpost.php?p=673266&postcount=128

Quote:
Originally Posted by joe tedesco
Let's just say that we are in the minority here, and that some feel that they can mix and match listed fittings anyway they want in spite of 110.2!

Comments about NEMA, not being an authoritative source are hilarious, and the members of the NEMA companies will agree with us, and others here who are aware of the poor workmanship.

The issue is one clearly defined - use the proper fittings for the purpose intended.

Who from the Inspection Community agrees with the opposition here?

Question:

Can anyone show us the text and images and training guides in the materials from the union and non-union shops that teach the methods shown in the picture?


In conclusion!

"From NECA 1, 2006, Article 10, Section K:

k) Raceway(s) to equipment subject to vibration shall be terminated in a box and final connections made with flexible conduit. The box shall be located as close as practical to the equipment terminals.

From NECA 1, 2006, Article 8, Section N:

n) When terminating in threaded hubs, the raceway shall be screwed tightly into the hub. The shoulder of a fitting shall rest securely against the hub."
__________________ :smile:
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NECA? Why are you talking about that when the NEC is what governs our installations?
 
If you could use a coupling on a all-thread end, what's the difference here?

It just occurred to me that NEMA would probably be very keen to bless this lashup if we had a "bonding coupling" with set screws on the ends. For dry work it gives them another slightly more expensive product to sell, and it gives the "truck solution" official blessing :grin:
 
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