Improper Use of Fittings

[joe tedesco]

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

As I interpret this picture, there is a malleable iron squeeze type connector securing the flexible metal conduit, and on the other end the steel set screw connector is assembled to EMT.

Both connectors are joined to a coupling with the connectors locknuts made up tight (?) to the coupling.

First, a connector cannot be used as a coupling unless so listed.


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


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

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

A better choice for this installation would have been to use 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.

 

[ibew441dc]

Joe Tedesco,

I have to say I agree with you 100%

I have come across this type of junction many times in the field.( to be honest before I knew better I did the same thing )

In short, you stated key points of why that picture is a violation. I think that many in the field still do this because the proper fittings are more expensive and less readily available.

I am almost positive that those that join different raceways in this manner are unaware of the possible hazards involved.

ibew441dc

 

[JohnJ0906]

Until I joined this forum, I didn't know better either. I was taught that this WAS the proper method. Thanks for teaching me better.

 

[stickboy1375]

What if you wanted to change from EMT to carflex? I would need a box or a combo fitting? Also, are you saying threading couplings are only good for joining threaded pipe together?

 

[mdshunk]

What if you wanted to change from EMT to carflex?

Then I would question the economic wisdom of running a metallic raceway when you are ending in a nonmetallic raceway.

 

[pismo]

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

As I interpret this picture, there is a malleable iron squeeze type connector securing the flexible metal conduit, and on the other end the steel set screw connector is assembled to EMT.

Both connectors are joined to a coupling with the connectors locknuts made up tight (?) to the coupling.

First, a connector cannot be used as a coupling unless so listed.


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


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

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

A better choice for this installation would have been to use 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.

This may not be "listed" but have you seen the flex to emt connectors? Some of the "listed" ones are very inferior to your picture.

 

[stickboy1375]

I have to disagree with #4, locknuts loosing up, if that were the case IMO you would not be allowed to even THINK of using EMT as a ground... reguardless of the use.... #2 I don't think that squeeze FMC connector is better as a ground than that threaded coupling...

 

[mdshunk]

I must admit, this picture and the accompanying text has me reeling. That picture could have just as easily been a picture of my work. I certainly struggle to do things the best way I know how, but this is one of those cases where "you don't know what you don't know". I don't understand some of the text explanations, so I'll have to do some research myself. I certainly believe Joe, that's for sure. Because Joe said it is enough reason for me to take it as truth. It is very educational, however, to research these things out. You can learn extra stuff too, quite by accident.

Thank you Joe Tedesco!

 

[jim dungar]

I do not see any violations.

I see a use of equipment that has not been tested, but that is in and of itself is not a violation. In fact even UL does not say you can not use fittings in this manner, UL just says they have not been evaluated as a grounding path.

It is up to the AHJ to accept or deny this application.

If this raceway has an internal grounding conductor then it appears that even UL would have less of problem with this use.

 

[iwire]

I do what is pictured.

I will continue to do what is pictured.

Inspectors in this area have no problem with it.

This may not be "listed" but have you seen the flex to emt connectors? Some of the "listed" ones are very inferior to your picture.

I agree with Pismo, most of the fittings that are made for this purpose are junk.

Joe what do you see as an electrical safety hazard?

 

[infinity]

I see no manufacturer that makes these transition fitting in sizes larger than 2". So how are you supposed to install a piece of 3" FMC on the end of a piece of EMT? This is a very common installation method. There are tens of thousands of installation like this all of this country.

 

[roger]

I agree with Pismo, Jim, Bob, Trevor, and the others that see this as being a safe installation.

Roger

 

[joe tedesco]

NEMA Information

NEMA Information

NEMA may not agree, ask them!

http://www.nema.org/stds/fieldreps/

Use of the proper fittings is the only issue here, and the comments are in that thought process.

Field Representative Training
Conduit & Cable Fittings

NEMA FB 2 Series​

FB 2.10 ​

Selection and Installation Guidelines for fittings for use with non-flexible metallic conduit or tubing ​

FB 2.20 ​

Selection and Installation Guidelines for fittings for use with flexible electrical conduit or cable​

NEMA FB 2 Series:​

Selection and installation guidelines​

NEMA FB 1 ​

Fittings, Cast metal boxes, and conduit bodies for conduit, electrical metallic tubing, and cable​

UL 514B ​

Conduit and Cable Fittings​

www.NEMA.org allows downloading of this type of information from their web site.

 

[George Stolz]

Joe, I'm glad you started this thread - I wanted to months ago when I saw this in the back of EC&M.

Can you go a step further and show (quote) where NEMA's site forbids the use of connectors in this fashion?

 

[joe tedesco]

NEMA Presentation

NEMA Presentation

http://forums.nema.org/wb/upload/2003-1-Field-Rep-Training-FittingsInstall.ppthttp://forums.nema.org/wb/default.asp?action=9&read=3613&fid=1198

 

[don_resqcapt19]

The standard does not say you can or can't used threaded connectors with couplings.

Armored Cable connectors having external threads may be installed into the threaded entries provided in certain boxes, enclosures, and conduit bodies. The external threads of armored cable fittings conforming to ANSI/NEMA FB 1 have straight threads (NPS). Threaded openings where these fittings may be installed may have either taper (NPT) or straight (NPS) threads, varying depth, and number of threads. Care must be taken


to ensure that a minimum of 3 threads of the connector are fully engaged with the threads of the conduit entry when wrench tightened.

[FONT=Arial,Bold]

It appears to me that as long as you have at least three threads engaged in the conduit coupling that you would be in compliance with this standard. It doesn't use the word coupling, but it does permit the connector to be use with staight or tapper thread fittings and the coupling is a straight thread. The wording in the standard is the same for all of the different types of connectors.
Don

​

​

​

[/FONT]​

 

[lowryder88h]

Improper fittings

Improper fittings

Been doing it that way for close to 40 years around here never had an AHJ reject it especially for 1.25" and above.

 

[jim dungar]

The standard does not say you can or can't used threaded connectors with couplings.
[FONT=Arial,Bold]

It appears to me that as long as you have at least three threads engaged in the conduit coupling that you would be in compliance with this standard. It doesn't use the word coupling, but it does permit the connector to be use with staight or tapper thread fittings and the coupling is a straight thread. The wording in the standard is the same for all of the different types of connectors.​

​

​

[/FONT]​

I don't see a threaded conduit coupling as being any different than a threaded hub in a conduit body. I even think the locknuts are optional, the fittings could be installed directly into the "threaded opening". As long as the connections are made up wrench tight and liquid-tightness is not required, an internal grounding conductor would remove any of my possible objections.​

 

[tkb]

I have done this connection many time without the locknuts though.

For 1/2" to 1" transitions I try to use a Cooper Spacesaver EMT connector to the flex connector and eliminate the Rigid coupling.

The Spacesavers are an EMT set screw connector with a female thread and a chase nipple instead of a locknut.

Just screw the MC connector or flex connector into this connector and save the chase nipple and locknut for another day.

 

[iwire]

NEMA may not agree, ask them!

You believe you know so why not show us specifically where NEMA (An organization that has no authority to make rules) states we can not do what is shown in your picture?

I also ask again what is the electrical hazard you see in that picture?