Meter after main bonding

[mark32]

This is not something I am working on, I just want to know the correct way in which to wire it. Let's say there is a main disconnect, it feeds into a metallic trough which then taps off to a number of meters which then feeds it's respective disconnect that will then feed a sub panel. (There is a graphic in Mike's book on Grounding depicting this very scenario on page 60 figure 250-126 if you have it) All of the equipment, except for the sub panels, are all grouped together. So, the trough must be bonded via a bonding jumper from the disc neutral/ground bar to a lug/distribution block in the trough. EGC's then originate from this spot and bonded to the meter's enclosure in which the neutral block is isolated and from there to the disconnects and then panel. Because the trough and meters are on the load side of the main the metallic nipples are not required to have bonding bushings. Is all of the above correct and how would you do it differently? Is the meter I described necessary here?

 

[gndrod]

This is not something I am working on, I just want to know the correct way in which to wire it. Let's say there is a main disconnect, it feeds into a metallic trough which then taps off to a number of meters which then feeds it's respective disconnect that will then feed a sub panel. (There is a graphic in Mike's book on Grounding depicting this very scenario on page 60 figure 250-126 if you have it) All of the equipment, except for the sub panels, are all grouped together. So, the trough must be bonded via a bonding jumper from the disc neutral/ground bar to a lug/distribution block in the trough. EGC's then originate from this spot and bonded to the meter's enclosure in which the neutral block is isolated and from there to the disconnects and then panel. Because the trough and meters are on the load side of the main the metallic nipples are not required to have bonding bushings. Is all of the above correct and how would you do it differently? Is the meter I described necessary here?

The mention of multiple meters, maybe if 6 or under, a six pack with six meter/disconnects would be a better way to go without trough and taps. (A main disco feeding if more than six meter center.)

 

[mark32]

The mention of multiple meters, maybe if 6 or under, a six pack with six meter/disconnects would be a better way to go without trough and taps. (A main disco feeding if more than six meter center.)

I agree with that, however this is one of those things that I'd like to comprehend regardless of which design I would choose to install. Thanks.

 

[al hildenbrand]

There is a second thread (or first, your perspective) that is asking virtually the same question. That thread is here.

Note Bob's (Iwire's) post referencing 250.142(B) Use of Grounded Circuit Conductor for Grounding Equipment. Load-Side Equipment.

 

[mark32]

Hi Al, that's funny such similar threads being started at the same time. I am familiar with that exception however it only mentions meter enclosures, wonder if the trough could be treated in the same manner and still be compliant?

 

[mark32]

Nevermind, I just found a graphic in Mike's book on grounding vs bonding on page 77. The graphic shows the wiring just as I described it in my first post.