FMC 90 degree Angle Connector

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infinity

infinity

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I have a situation where the engineer spec'd 3.5" EMT with a short piece of FMC at the end of the run to feed a transformer. The conduit contains 5-#600 Kcmil conductors. According to the tables in annex C, 3.5" EMT is permitted to contain 5-#600 conductors, the FMC is only permitted to contain 4-#600 conductors. But since the FMC is less than 24" in length the fill increases to 60% which now allows the 5-#600's.

My question is about the 90 degree 3.5" FMC angle connector, how would you know if the connector is listed for the 5-600's? The 5-600's are permitted in the EMT, and within the FMC nipple but what about the connector? I've never seen an FMC connector that listed the size and number of conductors permitted within them.
 
It's a good question and I do not know the code answer.

I do know that on the job I would just use 4" for this.

The difference in price between 3.5 and 4 is not that much and may be offset by a quicker installation.
 
hardworkingstiff said:
I'm curious of the proper way to make the switch from 3.5" emt to 3.5" fmc, or the switch from 3.5" emt to 4" fmc.
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I would use a GRC coupling or a GRC coupling with a reducing bushing.
 
hardworkingstiff said:
I'm curious of the proper way to make the switch from 3.5" emt to 3.5" fmc, or the switch from 3.5" emt to 4" fmc.

Will you use a C condulet, LB, rigid coupling?
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There is no 3.5" or 4" condulet listed for 5-600 Kcmil conductors. I will use 4" FMC and call it a day but was wondering if the 3.5" with the 90 degree connector would be a violation.:confused:

And yes the transition will be an EMT connector-rigid coupling-FMC connector.
 
Many suppliers, even the good ones, may have a very spotty inventory of 3.5" stuff on hand. I was involved with a job last year that had lots of 3.5" EMT and some of the couplings we got looked like they had been sitting on a shelf for years.
 
3-1/2" is not very good to work with. Ive found 4" to be cheaper due to it being more of a "standard" size.
I would see if they would allow you to install a gutter or junction box instead of that miserable fitting.
It always amazed me as to why we need to have a flexible connection to a transformer when we bolt it to the floor and the whole interior is on isolation pads.
 
I would do the same, but I thought I remember a thread that stated this is not proper use of these items.
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j_erickson said:
I was thinking the same thing while reading this thread.;)
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What makes you think that?

Because one or two very vocal NEC consultants think that.

Maybe one that has a monthly spot in a trade mag?

Have you seen any references to back that up?



IMO it is not a violation

The EMT connector is connecting EMT

The threaded coupling is coupling.

The FMC connector is connecting FMC.

I make my own all the time and will continue to do so until someone can show me it is a violation. :)
 
I'm with you, Bob. Any time flex 90's are used with big wire, I always increase the size of the flex. It'd be hard enough to get 5-600's through a 4" 90, it'd be an exercise in frustration with 3.5"

I do it the same way you do. Put a connector on the EMT, screw a bushing on the connector, then a rigid coupling, and finally the flex fitting. I usually go up only one size, the outside diameter of the rigid coup is not much bigger than the outside diameter of the EMT connector. It doesn't look bad at all.
 
608ecmWWH1.jpg
Joe Tedesco submitted this picture for ECM Magazine's "What's Wrong Here?" section in the 08/2006 issue, which you can be taken directly to by clicking here.

He later started this thread with the same picture, which apparently has moved from it's original location so it's not visible in the OP of that thread. It had mixed results and opinions.
 
iwire said:
What makes you think that?
Click to expand...

I remember a discussion here about that.

Because one or two very vocal NEC consultants think that.
Click to expand...

No. Well maybe. I forget the details.

Maybe one that has a monthly spot in a trade mag?
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Nope.

Have you seen any references to back that up?
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Nope.

IMO it is not a violation
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Agreed.

Now that you've called me out, and I've though about it, the discussion I am remembering involved burying the 90 degree flex connector behind plaster. And the discussion was probably a year ago. I haven't been here much lately.
 
Well, then welcome back, John. :cool:

That would be a cut and dried violation of 348.42. I think Bob was referring to the discussion I linked to above.
 
Nipple

Nipple

"But since the FMC is less than 24" in length the fill increases to 60% which now allows the 5-#600's."
It is not a nipple unless it extends between boxes, cabinets, etc, not to exceed 24". An extension of a raceway may not meet Chapter 9, Note 4.
 
I read over the linked thread and it got me questioning , if you cant go from one type of "listed connector" to another "listed connector" how would you transition from pvc to any other type of race way ? it is common , and the only way I can think of, to go from pvc underground up to metal by using a pvc female connector to a male type EMT or RMC connector.

sort of off subject , but I blame George for that:smile:
 
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