# Commercial service bonding question.



## nof123 (May 14, 2011)

Sorry for crappy pic










So the box with the on/off switch has a main bonding jumper, but the meter stack to the far left and the splice box (box adjacent to the panel) both also have main bonding jumpers in them.

My boss isn't the type of guy who can cite code to answer questions so I have to try to look them up on my own when I think something is questionable.

Theres a ground wire going from the far left meter stack to the ground lugs in the switch box and that is all bonded together. Isn't that a parallel path for the neutral current on both the ground and the metal parts?

Shouldn't there only be 1 MBJ and the neutral not bonded to ground anywhere else downstream of the fuses for this service or am I just wrong? He said it was fine like that.


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## Deep Cover (Dec 8, 2012)

If I was installing new....

-MBJ in main disconnect

-All gear bolted together is bonded

-Bonding bushings on the rigid nipples between tap box/trough/left meter stack

-No bonding jumper in meter stack

Is it against code the way it is? I'm not sure, we'll wait for someone more knowledgeable to come along.


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## seabee41 (Dec 21, 2010)

Is that all one service or two


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## nof123 (May 14, 2011)

1 600 amp service


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## Deep Cover (Dec 8, 2012)

I'm sorry, the last thing I said should have been....

-Bonding jumper in left meter stack


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## nof123 (May 14, 2011)

oh yea there are bonding bushings/jumpers in everything, just 3 mbj's. nothing's gonna happen im just tryin to find out if its a violation


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## ponyboy (Nov 18, 2012)

The only thing I think I know for sure is that the bond should be at the first disconnecting means. Everything should simply be equipment grounds after that, I think.


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## Deep Cover (Dec 8, 2012)

The three bonding jumpers aren't a violation on their own (although the one in the tap box isn't necessary).

Think of a typical duplex service. Both panels would have a bonding jumper then you would bond the two panels together by the GEC's.


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## wildleg (Apr 12, 2009)

I can't tell what I'm looking at.

It looks like one 600a disco, and 10 services. Is that what it is ? are those all utility owned meters ?

If the 600a switch is "the" service disconnecting means (one 600a metered service ie. everything else is load side and not utility owned) then I suppose the article that applies is 250.24 (5) ? (unless I missed an exception that applies)



> (5) Load-Side Grounding Connections. A grounded conductor
> shall not be connected to normally non–currentcarrying
> metal parts of equipment, to equipment grounding
> conductor(s), or be reconnected to ground on the load side
> ...


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## Deep Cover (Dec 8, 2012)

Is the 600A disco fused? If not, I say that detached stack is part of the service equipment and would need to have a neutral/ground bond.


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## nof123 (May 14, 2011)

yea its fused


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## nof123 (May 14, 2011)

wildleg said:


> I can't tell what I'm looking at.
> 
> It looks like one 600a disco, and 10 services. Is that what it is ? are those all utility owned meters ?
> 
> If the 600a switch is "the" service disconnecting means (one 600a metered service ie. everything else is load side and not utility owned) then I suppose the article that applies is 250.24 (5) ? (unless I missed an exception that applies)


they are 10 services owned by the utility company each with their own disco all protected by 600 amp fuses in the main disco



Deep Cover said:


> The three bonding jumpers aren't a violation on their own (although the one in the tap box isn't necessary).
> 
> Think of a typical duplex service. Both panels would have a bonding jumper then you would bond the two panels together by the GEC's.


good point, i like to overthink everything


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