# Simple but common one



## John (Jan 22, 2007)

I was changing some ballasts the other day and found this one. This was feeding from one fluorescent light fixture to another light fixture with the same connection at both ends. It appears that the wire in the AC cable was taken out and the AC to EMT to AC was run with pulled in wire because there was just a pair of untwisted black and white #14 wires going into the light fixture. Somebody was really getting into it because there was a bunch more just like it.:hammer: 

View attachment 6


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## MDShunk (Jan 7, 2007)

Do you think that is just the sheathing of type AC cable? I seem to remember certain uses permitted for 3/8" Flexible Metallic conduit (FMC, aka "Greenfield"), which is what that could also be. 

_*348.20 Size.
(A) Minimum. *FMC less than metric designator 16 (trade
size 1⁄2) shall not be used unless permitted in 348.20(A)(1)
through (5) for metric designator 12 (trade size 3⁄8).
*(1)* For enclosing the leads of motors as permitted in
430.245(B)
* (2) *In lengths not in excess of 1.8 m (6 ft) for any of the
following uses:
a. For utilization equipment
b. As part of a listed assembly
c. For tap connections to luminaires (lighting fixtures)
as permitted in 410.67(C)
*(3)* For manufactured wiring systems as permitted in
604.6(A)
*(4)* In hoistways as permitted in 620.21(A)(1)
*(5)* As part of a listed assembly to connect wired luminaire
(fixture) sections as permitted in 410.77(C)_

Could this be the case in your installation?


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## John (Jan 22, 2007)

I just assumed it was AC because it looked like AC. The point is the improper transition from EMT to some kind of flexible metal conduit. The transition fitting is not listed for the purpose.


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## MDShunk (Jan 7, 2007)

John said:


> I just assumed it was AC because it looked like AC. The point is the improper transition from EMT to some kind of flexible metal conduit. The transition fitting is not listed for the purpose.


That is the latest puzzle, indeed. Joe Tedesco brought this to light a couple of months ago. There are, indeed, fittings designed expressly for this purpose. People often call these "combination couplings". It would be a fitting designed, in this case, to change from EMT to FMC, without using a RMC coupling.

This information was related to me this morning from Scott Cline, Chairman of NFPA 70 (NEC) CMP 6, about a very similar installation:

_Q: The installation shown in the image is not the intended application or 
listing recognized by Underwriters Laboratories (UL) and VIOLATES 110.3(B).

A: My U.L. Code representative disagrees with you. He sees no violation of 
listing. Given that the connector/locknuts are properly tightened, the application meets the listing. 

Q: As I interpret this picture there is a malleable iron squeeze type connector 
securing the flexible metal conduit. On the other end is a steel set screw connector assembled to EMT. Both connectors are joined to a coupling with the connectors locknuts made up tight (?) to the coupling.

A: We agree as to what the picture shows. (Any pplication is reliant on proper workmanship regarding tightening of the parts. Uness egregious, a picture cannot show a failure to properly torque.)

Q: Frst, a connector cannot be used as a coupling unless so listed.

A: The connector is not used as a coupling; it is used as a method of connecting its raceway to the thread of the coupling. 

Q: Second, connectors have not been UL tested for resistance or ability to carry potential ground fault current when assembled to a coupling.

A: Connectors ARE tested for application to threaded connections. The mating threads of the coupling and the threads of a conduit body, etc., are the same. 

Q: Third, the threads of the connectors may not match those of the coupling 
raising the risk of connector pulling out of the coupling.

A: The male and female threads of electrical fittings are all made to the same 
NEMA standards. They are specifically made this way so that the installation of various parts and various brands will mate properly.

Q: Fourth, there is no assurance that locknut(s) will not loosen.

A: The assurance of a locknut or of any fitting not loosening over time is proper installation workmanship. This is irrelevant to the various allowable combinations of fittings. 

Q: A better choice for this installation would have been couplings designed and listed for the application. Fitting manufacturers such as O/Z-Gedney offer such a coupling for trade sizes 1/2" EMT - 3/8" FMC up to 2" EMT - 2" FMC; Bridgeport Fittings has sizes 1/2" EMT - 3/8" FMC up to 1"EMT - 1" FMC.

A: Single-purpose fittings such as those you mention would certainly be 
appropriate. They might even save on installed cost, but they are not the only correct solution. _

Mr. Cline offers the following, in summary: 

_The pictured installation does not appear to show a violation of 300.10's requirements for metallic continuity. It does not appear to show a violation of 300.15 in general, or 300.15 (F) in particular. It does not appear to show a violation of 358.42. Indeed, the screws and the connector's main thread/locknut appear to be fully seated._

Now that I offer that opinion of one man, I offer you this commentary of my own. Mr. Cline's opinion appears to run counter to NECA 1-2000, NEMA RV-3, NEMA FB2-10, and NEMA 2-20. 

We'll just have to wait and see how this plays out in the end. It's causing quite a stir in the mean time.


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## JohnJ0906 (Jan 22, 2007)

I know this is a contriversial topic, but are the manufacturers going to make a coupling to connect ANY type of conduit to ANY OTHER type of conduit in ANY size? I mean EMT to FMC, EMT to PVC, etc. And every size? And ALL the supply houses are going to carry ALL of them so we don't have to wait for one fitting to complete a job? To be honest, it seems that if this isn't proper, where are the proper fittings? They mention up to 2", but what about the larger sizes-3", 4" etc?


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## MDShunk (Jan 7, 2007)

JohnJ0906 said:


> They mention up to 2", but what about the larger sizes-3", 4" etc?


The people taking a hard line on this issue would have you use a pull box when a fitting is unavailable, and pull straight through it. In the case of a 4" EMT to a 4" FMC, lacking a manufactured transition fitting, they'd have you use a big junction box. EMT termintating on one side, and FMC terminating on the other, with a straight through pull. Junction boxes have been investigated for termination of all raceway types. I'm not sure how or if a threaded C-body has been investigated by the UL. I suspect that you'd be in the same boat as the RMC coupling if you used a C-body.


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## Pierre Belarge (Feb 3, 2007)

*I wonder?*

Depending on who one speaks to, we have distinctly different opinions/ideas about this topic. I myself do not see a physical/grounding path type of issue with this installation. Yet, I wonder if this would become a legal issue should a problem occur.


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## MDShunk (Jan 7, 2007)

Pierre Belarge said:


> Depending on who one speaks to, we have distinctly different opinions/ideas about this topic. I myself do not see a physical/grounding path type of issue with this installation. Yet, I wonder if this would become a legal issue should a problem occur.


I really can see this going either way if push came to shove in a courtroom. I might take a pretty savvy forensic electrician to ever pin the root cause of a particular accident on this sort of connection, I should think. In the mean time, it sure makes for interesting discussion. 

Glad to have your participation, Pierre. :thumbsup:


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## itsunclebill (Jan 16, 2007)

I think the issue I have with the lashup in the picture is that these (rigid)couplings are made to go on the end of conduit threaded with a taper. Consequently, the coupling gets tighter the further it is threaded onto the the conduit.

In the setup shown, the fittings are threaded with a straight thread and the only thing that "tightens" the connection is the shoulder of the fittings contacting the coupling. This type of "tightening" can be superficial at best since with the cast material the fitting is soft and will deform easily. This results in a connection that even when tightened snugly before assembly will sometimes loosen up during installation. Locknuts on the fittings prevents this with a fitting like the EMT connector, but the clamp used with the flex may not even have enough threads left after installation of a locknut to be snugged in the coupling without stripping and pulling out.

This suggests to me that using the couplings as shown in the picture may in fact be an issue. Seems like making couplings with a setscrew like some conduit bodies have would eliminate my concerns.

I've seen an EMT connecter that has a female thread and uses a "chase nipple looking" part that threads into the fitting from inside the box. Something like this would solve a multitude of problems if it was listed to make in line transititions as well.


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## Joe Momma (Jan 23, 2007)

Great commentary MD.

I agree fully with Mr. A (although the EMT connector is not steel)

And I think Mr. Q _{removed disparaging reference to illegal activity}_ and also probably on Gedny's payroll.

I also think that is a bass ackwards way doing things, but if that's the stuff you have on hand, then I don't see problem with the install.


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