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.
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?

It sounds to me that this inspector had dosed off during the seminar and awoke to hear only a part of a conversation.

If this is truly the case, it is a secret to me as well as it is to you.

Roger

Simularly, but not for Equipment Ground, around here SF, CA we must use grounding type lock-nuts, or ground bushiings on conduits for electrode, and bonding conductors. I don't see a problem for EG's.

But with 277/480, they want Ground bushings, or Ground lock-nuts on all concentric, and eccentric KO's. Something I dont see a point in.


[This message has been edited by e57 (edited 11-17-2004).]

Either I have had the same inspector, or they both attended the same seminar.
I couldn't believe what I was hearing, and when I laughed and told him he was crazy, it did not endear me to him much.

Soare's Book on Grounding (8th Edition, pp129) has a report on a test conducted on conduit fittings and locknuts.
"Conduit Fitting Ground-Fault Current Withstand Capability" , issued by UL, 6/1/1992
In a nutshell,[my paraphrasing] of Over 300 assemblies tested, from 10 manufacturers, 7 were deemed as insufficient. Yes, 6 were EMT fittings with zinc die cast locknuts without serrations installed on painted surfaces. (an example of the test, 3/4" fittings were subjected to 1530 amps for a 6 second period).

The conclusion made--
"5. As a result of the tests, it was observed that if the fitting provides good electrical contact to both the enclosure and the conduit, the fitting will provide a suitable equipment path for fault current."


Good enough for me unless it's been superceded


My Mickey Mouse inspector wanted grounding locknuts, bonding bushings, or Myers hubs for all the EMT fittings. He wouldn't write it up when I asked him to. I just made sure that there was no paint under the locknuts, and left it.
I think the TI electrical contractor told me that he wanted them on the 4-S boxes, too.
He also wouldn't final the building shell because I had a bad light bulb.

It prompted me to (of course) bring it to ECN
https://www.electrical-contractor.net/ubb/Forum5/HTML/000678.html


I think he needs to get his money back for the seminar.

PS, sandsnow, I do mostly service & warranty, & small TI's. We've not been "formally introduced". My last trip into your town was to advise the girls at your new Chamber of Commerce office (our company did the work) to just leave the occ sensors alone. They were trying to use them like the wall switches in their homes, with "frustrating" results (& I know some old AJS guys)



[This message has been edited by electure (edited 11-17-2004).]

electure
AJS, now that brings back memories. I still see guys from there.
Anyway, what you posted from the Soare's Book was just what I needed. I suspected something like that. He only heard half of the story.

My conclusion to the test is then to make sure the locknut cuts through the paint. I need to read that portion of the Soare's Book first.

Thanks again.

The inspector Electure is talking about made us run ground wires in ALL EMT conduits. I had 7' lengths of EMT running from 4s bracket boxes for switches to a J-Box in the ceiling. All of them needed grounds with bonds to the back of the box. Also, I fully tightened down all set screws and used a hammer and a screw driver on all lock nuts. So it wasn't an issue of a poor install.

I wonder what he is going to say when the 2002 NEC is adopted here in Cali with the new addition explicitly adding EMT as a EGC.

2002 NEC
358.60 Grounding. EMT shall be permitted as an equipment grounding conductor.

Oh did you not know.... the "hammering a screw driver on the locknut is not an acceptable method. The Code says wrenchtight, not hammered with a screwdiver tight."

I was told that by an Inspector once, and luckily I had a little pair of Knipex channel locks on me... So I could make the lock-nuts "wrenchtight".

He nearly quoted a something I saw on an add for Klien "lock-nut pliers" something about to conform to the NEC all lock-nuts must be "wrenchtight", So now Klien makes the handy dandy not available anymore pliers, specificaly for the purpose.

Do you think I own a pair of "lock nut pliers"? NO!

I hammer them with a screwdriver (The Beater), and a pair of linemans, like everyone else.

LOL

I wonder what that inspector would say if he saw me use a Bosch Bulldog set on hammer to tighten larger steel locknuts?

Try it before you laugh to much.

Tighten a locknut with handtools as tight as you can, then put the Bulldog to it. It will spin the locknut like it was loose.

You will not have worry about the locknut cutting through the paint.

Bob

I don't have my code book with me, but I believe it says to make things wrenchtight. Though it doesn't say how you must achieve that so I am in full compliance

Bob you are probably violating some torque spec using your Boshe like that :P

iwire said:

Don't you run the risk of stripping the threads on the nut or the connector by over-tightening it like that?

I know I've sheared threads off on terminal screws by "overtightening" them. Well, they were cheap devices anyway but it's still aggravating to waste time having to replace the device AGAIN.

Well, I did a google search on lock-nut wrenches and came up with this doozy.

Links to pictures because they are so large.

http://www.premiertool.com/283ff420.jpg

It looks like a can opener on steroids!

Wonder if it's worth looking into.

[This message has been edited by SvenNYC (edited 11-19-2004).]

[This message has been edited by SvenNYC (edited 11-19-2004).]

"Try it before you laugh to much. "

Too late, I just got off the floor!

Really? I was almost heartbroken for a moment.

Go to http://www.kleintools.com/ and do a search for D333-8:


Still there... thank goodness!

I've got a set of those pliers. If they weren't fairly good for reaming 1/2 and 3/4 thinwall, I'd send them to you for the price of shipping.

If you use them, be careful or use fairly thick gloves. You (I) generally have to use fingertips to hold the jaws down on the locknut, and they tend to bite without warning, when they jump off the locknut.

Often.

[This message has been edited by Dallas (edited 11-18-2004).]

I use those yellow klein pliers all the time. It is nice for making the pipe end round again. I use it for tightening connectors. But I grab the connector side. It's also my spare reamer.

C'mon, now, be honest
Which of you hasn't used a screwdriver and "electrician's hammer" (Kleins) ?

Directly from Soares:




I saw one of those little locknut wrenches at the wholesalers, but when it broke off in my hand at the counter, I opted not to buy it.

I've often wondered what is the correct OSHA way to tighten a locknut by tapping it and why Klien doesnt make a locknut "tapper" so people can work safely. People could be maimed for life!!!!!

BTW, my friend got his issue resolved in his favor and the AHJ was gracious in conceding to his position. Good to hear that ego's were kept in check.

Perhaps what someone needs to do is create a pair of racheting pliers specifically designed for locknuts, where the racheting mechanism would tighten the locknut.

Just a thought...

Sir Arcsalot:

Or even just a "crow's foot" attachment for existing socket wrench handles!!!

Car mechanics already have things like that, so the concept exists. Just someone has to come up with a new die to make them in the shape we need.

Picture the open end of a wrench, but intstead of a handle, you have a square hole. The post from the ratchet handle fits into this and it turns like a regular wrench.

They're a breeze to use.

Yeah, I've used "crow's feet" before and they are indeed very handy (it was the ONLY way I could get the brake flex line off my old Chevy truck!!!).

There's just GOTTA be a better way than a screwdriver and brute force!!!!

I'm glad everything worked out with the inspector. Now if he can just take care of the issues on the other thread without getting too riled up....he is the same guy, I think ...Oh well
*************************
OK,Here's a couple more for anyone that still doesn't believe in the screwdriver. Thanks to Joe Tedesco for sending them over

These are stills from an NFPA Expert Training Video.








(I wonder if the screwdrivers have a warning label on them not to strike them?)

[This message has been edited by electure (edited 11-20-2004).]

So I looked up 256.96 (A) out of the NEC
it didn't read the same. whare did that come from?

Bucketman, this is showing that the locknut (as part of the fitting) actually cuts into the metal through any non conductive paint per the requirement of 250.96, as well as showing a screwdriver tightening it is a common and accepted technique.

Roger

Locknut torque wrenches? ;-)

Bucketman,
If you're talking about the text image rather than the pictures, it came from
"Soares Book of Grounding", published by the International Association of Electrical Inspectors, not the NFPA (and incidentally available through ECN's bookstore).
It's considered to be the most authoritative book available on grounding and bonding.

Well, since I'm here anyway, here's what happens when the fitting is tightened (maybe with a wrench?) and the locknut doesn't pierce the paint. Just a 20A 120V circuit that had a ground fault. These were both tight.


1. This KO was slightly oversize, looked like someone went a notch too far with a step drill



2. Here's the conn on the other side of the box. This KO was the proper size.




3. Inside shot of the conn in #2




[This message has been edited by electure (edited 11-22-2004).]