EMT connector locknuts for grounding

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sandsnow

sandsnow

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Southern California
Ok, this is not a joke. A contractor called me and told me an inspector in a neighboring jurisdiction had told him EMT connector locknuts were no longer acceptable for grounding when using the conduit as an equipment ground. All locknuts have to be replaced with the grounding type locknut with the little screw. :eek:
The inspector said he was told this at a seminar and no other info was forthcoming. I checked the UL info on EMT fittings and there were no restrictions. The KO's were cut accurately and there were no concentric or eccentric KO's. Voltage was 480.
Anybody heard of anything regarding this? :confused:
 
Re: EMT connector locknuts for grounding

Someone is passing out bad info in my opinion, just want to cover my b*** on the 0.000001% chance there is something to this.
 
Re: EMT connector locknuts for grounding

I actually heard something like this not too long ago as well. Supposedly came from UL.

I suspect urban legend.
 
Re: EMT connector locknuts for grounding

I found out this comes from a test UL did with EMT locknuts, which was written up in the Soare's Book on Grounding. 8th Edition pp129. of a UL report from 1992.
Out of 300 connections evaluated, 7 did not measure up and 6 were EMT connectors on painted surfaces.

The conclusion was if the fitting makes good electrical contact, then it is sufficient.

The above was a paraphrase of a paraphrase so don't take it as complete.

I need to read it in the Soare's Book and look up the UL report.

This is how myths are created. The inspector only heard part of the story.
 
Re: EMT connector locknuts for grounding

I had an electrician recently tell me I needed a bonding bushing on a plastic liquid tight connector for an insulated GEC.
 
Re: EMT connector locknuts for grounding

I just read the Soares reference, and I can see how someone may interpret it to say that certain type fittings may not be effective. But as in another thread on this site, the Soares book is not the NEC. I also referenced the UL White Book and did not see any reference as to the locknuts not being permitted as part of the effective ground fault current path. 250.97(C) is still in effect as far as I can tell.

Pierre
 
Re: EMT connector locknuts for grounding

It's probably because the inspectors are so mean out here Larry. Just bond everything, don't get 'em upset. :D

The chicken wire in the stucko's not bonded! :mad:
 
Re: EMT connector locknuts for grounding

pierre
I haven't read that reference in the Soare's book yet. I think this is a case(as in any listed product) that you have to install it correctly.

Sam
I want that lath bonded, you trying to kill somebody!!!!! :D
 
Re: EMT connector locknuts for grounding

Nema doesn't prohibit using the factory supplied locknuts on listed fittings either, although they do require cleaning paint from painted surfaces.

Go to this link http://www.nema.org/index_nema.cfm/1427/0DA3EA97-80F2-490F-81EE45D6DC548DAF/

and click on "FB 2.10-2003, Selection and Installation Guidelines for Fittings for Use with Non-flexible Metallic Conduit or Tubing (Rigid Metal Conduit, Intermediate Metal Conduit, and Electrical Metallic Tubing)". Go to page 5. (not page V)

You will have to register to upload the documents on this NEMA site.

Roger
 
Re: EMT connector locknuts for grounding

The older lock nuts with the jagged teeth did a great job of getting through the paint. The newer ones with the molded ridges, I don't know.
 
Re: EMT connector locknuts for grounding

Unrelated to the question - Could not help but notice the distinction that NEMA makes between conduit & tubing in roger's post.

Reminds me of an earlier thread about whether EMT was conduit. I believe it is the intention of NEC, when it uses the term conduit, it is not speaking of EMT.

If that is the case, possibly the 2005 Code or later will correct the "typo ?" in 358.24.
 
Re: EMT connector locknuts for grounding

Neither "conduit" or "tubing" is defined in the NEC however the definition for raceway includes both. What does this tell us if anything? :confused:
 
Re: EMT connector locknuts for grounding

electricman2,
Y'all (Texas term) sure giving me a hard time about whether EMT is conduit. I know people call it thinwall conduit & I know that it is raceway.

The earlier thread I speak of was under Elect. Contracting & Estimating/Mgmt. & was started on 9/22/04 under the topic "EMT conduit". Sorry, I do not know how to post it here.
 
Re: EMT connector locknuts for grounding

I heard an instructor at a recent code class suggest the punched versus molded locknuts were preferable, and also he quoted an unnamed study that suggested set screw connectors provided a better path than compression EMT fittings.
 
Re: EMT connector locknuts for grounding

The compression fittings are listed as raintight and therefor I would expect more loss of continuity over all based on where they're used.
 
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