Proper coupler from 1/2" EMT to 3/8" FMC?

P

pfus

Member
Location
Chicago NW burbs
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Elect. Engineer
It's confusing because it has contradicting info:

"For Use With FMC/EMT Conduit"

"Used to join 1/2" EMT and up to two 14/2 and 12/2 Romex, Non-Metallic Cables."

There are others that leave no doubt:

1732892599166.jpeg 1732892639307.jpeg1732892621990.jpeg
 
pfus said:
There are several products that look like this:
www.butlersupply.com

Bridgeport® 280-DC Combination Coupling, 1/2 to 3/8 Inch EMT, Zinc Die Cast

Bridgeport® 280-DC Conduit Combination Coupling With 2-Way Phillips/Slotted Head Screw, 1/2 to 3/8 in, For Use With FMC/EMT Conduit, Die Cast Zinc, Ball Burnished
www.butlersupply.com www.butlersupply.com
But almost look like a NM clamp.

Vs.


Is the first type really an acceptable method to connect 3/8" FMC?
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I clicked onto the site and it appears the Bridgeport fitting is for 1/2" EMT to one or two 14/2 or 12/2 NM cables.
 
Just curious , it only took me 35 years to find out that you are not allowed to make a home made transition fitting using a RMC coupling. Found thus out at one of the first great local IAEI meetings I attended. So being its way easier to stock RMC coupling do many sparkies still make the transition from say EMT to AC or MC cable? Made countless ones up wrench tight and never had one cone loose. The two companies that I worked for did not want to bother stocking countless transition fittings.
 
JohnE said:
What transition did you make that is prohibited?
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Take two standard connectors (intended for holes in boxes), and join them with an RMC coupler.

This appears to fit together and create a transition coupling, but isn't an evaluated use for the components.

IMHO this very likely creates a perfectly suitable transition, but since it hasn't actually been evaluated....

Jonathan
 
winnie said:
Take two standard connectors (intended for holes in boxes), and join them with an RMC coupler.

This appears to fit together and create a transition coupling, but isn't an evaluated use for the components.

IMHO this very likely creates a perfectly suitable transition, but since it hasn't actually been evaluated....

Jonathan
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I'm just not understanding what code or standard this violates.
 
LarryFine said:
Couplings are made for joining conduits, not fittings.

Fittings are made for KOs and locknuts, not couplings.
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So what, exactly, would you fail the job for? (And while I haven't been on here much lately, I greatly respect your opinion, Larry)

MA does have some amendments that may not apply nation-wide....
 
JohnE said:
So what, exactly, would you fail the job for?
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Fittings are supposed to be used in accordance with their listings and instructions.

This is kind of an exception to the what-isn't-prohibited-is-allowed generalization.

JohnE said:
(And while I haven't been on here much lately, I greatly respect your opinion, Larry)
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In MA, the amendments to the NEC state:

90.4 Enforcement. This Code shall be used by the authority enforcing the Code and exercising legal jurisdiction over electrical installations. The authority having jurisdiction of enforcement of the Code shall accept listed and labeled equipment or materials where used or installed in accordance with instructions included with the listing and labeling. The authority shall have the responsibility for deciding upon the approval of unlisted or unlabeled equipment and materials, and for granting the special permission contemplated in a number of the rules.

I realize this forum is based on NEC primarily. But given this article, I can see the argument to allow the installation in OP, at least here in MA.

But MA is a separate discussion, I realize that. I do recognize and appreciate the "permissive code - what is isn't prohibited is allowed". I had a lot of difficulty when my day job changed to enforcing MA Zoning, which is entirely opposite - if it isn't allowed expressly, it is prohibited....but I digress...
 
Often, what is 'not allowed', is just stupid.
winnie said:
This appears to fit together and create a transition coupling, but isn't an evaluated use for the components.

IMHO this very likely creates a perfectly suitable transition, but since it hasn't actually been evaluated....

Jonathan
Click to expand...

I have been evaluating connector/rigid coupling/connector for over thirty years. Works just fine. :cool:
 
garbo said:
Just curious , it only took me 35 years to find out that you are not allowed to make a home made transition fitting using a RMC coupling. Found thus out at one of the first great local IAEI meetings I attended. So being its way easier to stock RMC coupling do many sparkies still make the transition from say EMT to AC or MC cable? Made countless ones up wrench tight and never had one cone loose. The two companies that I worked for did not want to bother stocking countless transition fittings.
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I am guilty of doing this countless times when I didn't have a transition fitting. I never was called on it or realize it wasn't permitted unit i read it on this forum.
 
The paper that @infinity links is spot on about why it is plausible that such home made transition fittings might not work properly...buy I'd lay money (not much :) :) ) on my claim in post #10. Rephrased: 'They probably work just fine but have not been evaluated to demonstrate that they work just fine.'

My guess is that an officially evaluated component to allow home made transition fittings would have something that looks like a conduit coupling, but with straight threads, and possibly special locknuts to firmly bind the connector to the coupler.

Maybe there is a market?
 
winnie said:
The paper that @infinity links is spot on about why it is plausible that such home made transition fittings might not work properly...buy I'd lay money (not much :) :) ) on my claim in post #10. Rephrased: 'They probably work just fine but have not been evaluated to demonstrate that they work just fine.'

My guess is that an officially evaluated component to allow home made transition fittings would have something that looks like a conduit coupling, but with straight threads, and possibly special locknuts to firmly bind the connector to the coupler.

Maybe there is a market?
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There are transition fittings that are approved.
We just use a box to transition from one to the other.
We were rejected for it in a few buildings for using the connector coupling connector setup.
And they were a long ways away from our factory so it cost us quite a bit to fix it.
We don't do that anymore.
 
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