Improper Use of Fittings

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IBEW, for your information yes I have and I understand both of them.

348.6 Listing Requirements
FMC and associated fittings shall be listed.

358.6 Listing Requirements
EMT, factory elbows, and associated fittings shall be listed.

When the listed connectors are installed on either, what the connector goes into is a completely different item.

Using your logic the enclosure the Listed Fitting goes into must be also be listed in the articles huh? :rolleyes:

Don't go getting up on a high horse now telling people they haven't read the references.

The only person not providing substantiation here is Joe, sorry but that's a reality

Roger
 
Joe,
Please cut a paste the words from UL Guide DWTT that says the threaded connector is not to be used with a threaded fitting or coupling. I can't finde them.
Also as far as the moderators sticking together, I have often posted comments that did not agree with the position of my fellow moderators.
Don
 
joe tedesco said:
PS: I have some really good violation pictures from Syracuse, NY, or should I say $$$ the crossed Neutral city?
Click to expand...

And here I thought every city had old house wiring as bad as Syracuse's... :)

If you need more photos for your collection, let me know. :) :)
 
roger said:
When the listed connectors are installed on either, what the connector goes into is a completely different item.

Using your logic the enclosure the Listed Fitting goes into must be also be listed in the articles huh? :rolleyes:

Roger
Click to expand...

Roger,
You have to use some common sense here. Is a rigid coupling listed as a raceway? Or is it a coupling for a rigid raceway? It definetly isn't listed to couple EMT and FMC.

If what the connector goes into is a completely different item , I wander why manufactures make listed products for this application.

If you were to understand my logic you must first understand the definition of a fitting, (article 100 def.) Enclosures, boxes, etc are not fittings. Couplings and connectors are.

ibew441dc
 
ibew441dc,
You have to use some common sense here. Is a rigid coupling listed as a raceway? Or is it a coupling for a rigid raceway? It definetly isn't listed to couple EMT and FMC.
Click to expand...
Yes we do have to use some common sense here. A rigid coupling is a fitting with straight threads. The NEMA standards says the connectors can be used with some threaded items with straight threads. I see no problem when it is used with a coupling and I see nothing in the NEMA standard, the UL listing or the NEC that says it can't be used with a conduit coupling.
Don
 
joe tedesco said:
Ryan, I am surprised at your comments, you teach the NEC and proper use of the Code, and still will allow the misuse of fittings in violation of 110.3?
Click to expand...

Joe, when I teach the NEC I teach the Code and nothing but...I leave my feelings and opinions out of it.

Having said that, when I inspect I exercise a little discretion. If you really think about it, you could probably fail 99.9% of the installations in the world. Is that really the intent of enforcement? I don't think it is...I think making the installation safe is the intent. If reducing washers are listed to carry huge amounts of fault current for a prolonged period of time (and they are), then I am SURE the connections you show will as well. In fact, I would be willing to bet that the installation shown would pass the test used by UL for bonding with flying colors.
 
The words I would be looking for are (for example) "EMT fittings are not suitable for use with RMC couplings"

show me that in the UL White Book and I'll start rejecting tomorrow.

if an AHJ wants to reject the install because UL has not investigated it, then that is up to them.
 
300.15 Fittings and connectors shall be used only with the specific wiring methods for which they are designed and listed.

I think that we should be reminded of this rule.

Question: Is the EMT connector, or is the FMC connector and locknuts designed and listed to be used as shown in the picture?

If we could see the substantiation for this rule in one of the proposals or comments they may give the answer!

​
 
Isn't the coupling designed to accept straight or tapered "male" threads?

Aren't the EMT and Flex connectors designed to be installed using their "male" threads?

Other than not being investigated I can not find anything in UL that even discusses this application.

I have not seen any manufacturer's literature that says not to combine straight and tapered threads.
 
IAEI UL Question Corner Article

IAEI UL Question Corner Article

IAEI UL Question Corner

http://www.iaei.org/subscriber/magazine/06_c/2006_may_questioncorner.pdf

See the second question, it is getting close to this subject with some similar issues. :)

Q A common practice I see in
the field is EMT offset connectors
screwed into hubs
on outdoor enclosures. Are
EMT offset connectors or any EMT
connectors or fittings Listed for use
with threaded hubs, such as on a conduit
body or Myers hub?

A All hubs are intended for
use with threaded conduit,
not fittings. Hubs are provided
with a tapered thread, and
so is threaded conduit such as rigid
metal conduit or intermediate metal
conduit (IMC). EMT fittings have
a straight thread and are designed
for use with a lock nut, intended
to secure to an enclosure through a
knock out or punched hole.
When the straight thread of the
connector or fitting enters a hub in a
wet location, the wet location rating
may no longer be valid because the
wet location rating of the hub depends
on the tapered thread engagement
of the tapered conduit thread
into the tapered thread of the hub.
With a straight threaded connector,
the thread of the connector never
locks into the tapered thread of the
hub, therefore not providing a seal
to keep out moisture.
An EMT fitting marked for use
in a wet location is provided with
or is used with a gasket between the
fitting and the hub. When the fitting
is tightened the gasket can be
squeezed out from between the fitting
and hub and may not provide a
means to keep out moisture.​

Other considerations with straight
threaded connectors into a tapered
threaded hub may be grounding.
Depending on the installation of the
straight threaded connector into the
hub, the contact may not be tight
enough to assure an effective groundfault
current path. The connection of
straight threaded connectors, such as
EMT connectors, is not evaluated
with hubs as part of their Listing.
Hubs are Listed under the product
category Conduit Fittings (DWTT).
EMT fittings are Listed under the
product category Electrical Metallic
Tubing Fittings (FKAV). The Guide
Information for DWTT can be located
on page 22 in the White Book
and FKAV on page 33 or online by
entering DWTT or FKAV at the
Category Code search on UL’s Online
Certification Directory located
at www.ul.com/database​
 
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Joe,
I posted that in an earlier thread because I thought it was saying what you are telling us, but it doesn't really come out and say that. All it really tells us is that we can't use EMT connectors with hubs for a watertight installation and that the combination of a male thead connector with a female thread fitting has not been evaluated for grounding. I wonder why the NEMA standard comes right out and tells us that male thread connectors are suitable for use with female thread fittings?
Don

edited for spelling
 
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Don:

Thanks, I sent each NEMA representative an email message asking for clarification covering the subject of this thread.

I am not too sure that any of them will reply, and sit here with questions as to how we can get to the bottom of this, that's what's fun aout this place.

Many thanks to earlybirds like you, roger, iwire, and others who can't wait to turn on the computer to see the questions, or how they may be of help!

I try to fulfill that need too, and I have the time to do so because my computer is always on.

I spend lots of time, it is so much fun that I even have a Palm TX I can use for the Free WiFi now available in the Boston downtown area.

You may never know where I am, unless its during one of my classes where I do keep a second computer open for use to add questions from students knowing that you or others are nearby.

I always tell them that we can look for an answer before the end of the day from the Council of Elders.

Are you are still working in the Chicago plant ready to take care of any problems?
 
"The issue is one clearly defined - use the proper fittings for the purpose intended."

I think the "purpose intended" is construed too narrowly.

A listed electrical fitting with a male thread is intended to be screwed into another listed electrical fitting with a female thread. If that fitting is intended to include use as a grounding conductor, then any other fitting intended to be used as a grounding conductor should serve equally well.

I would skip the locknuts because I think the fitting without the locknuts makes a better joint. The interference of the male/female threads, or the force agains the shoulder of the mating parts, creates an excellent connection. The locknut does nothing to improve it.
 
EMT connectors are permitted to be assembled into threaded entries of boxes, conduit bodies or internally threaded fittings having tapered threads (NPT). According to the Steel Tube Institute of North America, and NEMA FB 2.10. Therefore I don't see this as the issue for installation.

However, installed as shown, there is a strong likelihood that the EMT will not remain firmly butted against the fitting?s end stop due to strain on the set srew connector from the weight of the attached assembly pulling downward. Therefore, by not have a properly placed support, IMO the assembly could possibly fail due to improper torque on the set srew connector, and lack of proper support at the fittings.

The NEC requires minimum support requirements, however, additional support is problably needed. Without firm proof, by calculation, that this assembly will maintain it's integrity, I could see how an inspector could choose to not allow this method. In that regard, I have to support Joe's observation that this does not meet code, but because there is a ack of support and strain relief at the fittings.

As a side note, our companies specifications do not allow this type of arrangement.
 
Improper use of fittings

Improper use of fittings

I think this sort of assembly is perfectly acceptable.

It simply is not possible to anticipate every possible combination of every sort of hardware.

Even if loose, the connections at the threaded coupling can hardly be a worse grounding path than that of a "jake" coupling between two pieces of flex.

Perhaps the specific combination was never evaluated; however, all the bits & pieces use standardised threads to connect- a connection that WAS evaluated.

It is not reasonable to mandate that a specific piece of hardware be used simply because it exists. That would be comparable to saying that I cannot mount an ordinary box to a bracket, as boxes exist that already have brackets on them.
 
Improper use of fittings

Improper use of fittings

Joe, that answer in the "UL Question Corner" is simply incorrect.

A common outdoor "Bell" box certainly has hubs. Yet, the threaded entries to these boxes readily accept 'straight' threaded connectors. Therefor, the hubs must have straight, and not tapered, threads.

Likewise, conduit bodies differ in their threads. Brand "A" will readily accept EMT fittings, while Brand "B" will not.

The 'joker' in the UL answer is the preface 'intended for use with rigid...' I say that if the threads fit, the use is correct.

But, again, not all hubs are intended for use with rigid.
 
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