stacking ground lugs

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stew

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supposedly got a correction this am for my install where I stacked 2 ground lugs on one 1/4-20 machine screw. havent seen the correction number yet but i think its something like 110.3. anyone chime in on this? I have done this before and never got called.seems like a pefectly ok way to do it and I cant see where 110.3 would apply. I will look on the lug package to see if there are actually any instructions but having used this method many times It has never come up. hmmmm
 
stew said:
supposedly got a correction this am for my install where I stacked 2 ground lugs on one 1/4-20 machine screw. havent seen the correction number yet but i think its something like 110.3. anyone chime in on this? I have done this before and never got called.seems like a pefectly ok way to do it and I cant see where 110.3 would apply. I will look on the lug package to see if there are actually any instructions but having used this method many times It has never come up. hmmmm
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I'm on your side unless someone can find instructions for the lugs that says otherwise. I would sure hope that there is a little explanation and not just mention of 110.3.
 
I think he is just inventing something out of his own mind. The real funny thing is I installed a 75 kva stepdown transformer at another location in this plant about a year ago. used flex from the j box and to the disconnect. There were grounds pulled in the emt and to the load side. guess what? stacked the lugs in the disconnect and the j box. same inspector,no call. maybe he just had a hard nite eh?
 
Gee, these are ground lugs for non current carrying conductors so it should be a non issue. Now if these were for grounded neutral conductors it would be a another issue.
 
templdl said:
Gee, these are ground lugs for non current carrying conductors so it should be a non issue. Now if these were for grounded neutral conductors it would be a another issue.
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That was my thinking, but even then that would only apply to MWBC's.
 
We do it all the time without issue fortunately, of course it's nice to have the proper lug with all the holes you need.
 
Could it have something to do with the amount of surface area of the lug that is in contact with the mounting surface? The bottom lug would obviously have the entire surface in contact but the top lug would only have the surface area of the lug below it to mate up to.
 
So you mean something like this?

IMG_0344.JPG
 
Microwatt said:
Could it have something to do with the amount of surface area of the lug that is in contact with the mounting surface? The bottom lug would obviously have the entire surface in contact but the top lug would only have the surface area of the lug below it to mate up to.
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You do have a point but is it a current carrying conductor? If so would there need to be a load test of the connection to establish an acceptable temperature rise as there would be in in toher teminations such as neutrals and line conductor terminations. In addition, unlike neutral conductors you are allowed to place multiple EGCs under one screw and I can't recall seeing any restriction to the number condutors that are allowed, as many as can be squeezed in maybe?
 
If I would have had a double barrel lug I woudnt have stacked them. Just had somewhat limited room and just stacked them like I always do in this type of install. No sense at all in 2 separate holes. The gound connection is very complete. the first lug hits the box and the full tab of the second rides upon the first and is firmy bolted together. Thier is absolutly no code issue except the on that has formed in this inspectors mind. I dont think he had his coffee yet this am as he was at the site waiting to get thru the office at a bit prior to 7 this am. Anyhow I "corrected" it the way his mind seems to think 110.3 reads as it pertains to stacked lugs.I am goinf to forward the T&B page to him in the morning and talk a bit more to him also. I just hate it when I really feel I am correct and then have my work questioned in this fashion.
 
stew said:
I just hate it when I really feel I am correct and then have my work questioned in this fashion.
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Yeah, it happens, especially when you're an employee and you have a boss!:D I try to roll with the punches, everybody seems to have their own idea of what's right....
 
From page 465 of the 2011 White Book (Wire Connectors - ZMKQ):

INSTALLATION
Wire connectors are intended for use in installations covered by ANSI/
NFPA 70, ??National Electrical Code?? (NEC), and should be installed using
the prescribed manufacturer?s installation instructions.
Stacking of connectors (multiple connectors assembled using a single
bolt, nut and washers) may be permitted where mechanical interference is
reduced or eliminated with the use of offset tangs, stacking adapters, and
the like. The surface contact area of the mounting tang should make complete
contact with the mounting surface or the previously stacked connector.

So it is permissible IF you use lugs designed to be stacked or some sort of adapter. Notice that the Thomas and Betts catalog lists both stacking and non-stacking lugs.
 
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