bonding of neutral buss(s) to sub panel cans

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mikewo

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I upgraded the service on an old triplex with a "four meter socket + mains" enclosure feeding new subpanels for each of the units + the house panel. There is no single main for the whole service there are essentially four main breakers for each of the sub panels. The service is 120/240 single phase, the feeders are 3/0.

The neutral buss is bonded to the can in the
meter(s)/mains(s) enclosure. I did not bond the neutral buss(s) in the sub panels to their enclosures, because I learned that you only do that once at the main neutral buss. The inspector says I have to bond the neutral buss at each sub panel. I say not. What do you think?


Thanks for the reply
 
Re: bonding of neutral buss(s) to sub panel cans

The grounded service entrance conductor is bonded in the meter, it is also bonded in the main by the main bonding jumper. Only one main bonding jumper in the system. Grounds and neutrals are to be seperate after that not to be put back together after that.
 
Re: bonding of neutral buss(s) to sub panel cans

Mike,
If the grounded conductor is bonded at the service disconnects then you must use a 4 wire feed to the panels and you are not permitted to rebond at the panels. The GEC connection must be made at the service disconnects.
Don
 
Re: bonding of neutral buss(s) to sub panel cans

250.24(A)(1) General. The connection shall be made at any accessible point from the load end of the service drop or service lateral to and including the terminal or bus to which the grounded service conductor is connected at the service disconnecting means.Anywhere from the service drop(starting point)no further than main disconnect) ending point.Anywhere in between and accessible. There is also somewhere and I can't find it where it is said in close proxsimity of service or something of that nature I will find it and post.
 
Re: bonding of neutral buss(s) to sub panel cans

I found the Article. (A) talks about before the main.(B)talks about after the main.
250.142 Use of Grounded Circuit Conductor for Grounding Equipment.
(A) Supply-Side Equipment. A grounded circuit conductor shall be permitted to ground non?current-carrying metal parts of equipment, raceways, and other enclosures at any of the following locations:
(1) On the supply side or within the enclosure of the ac service-disconnecting means
(2) On the supply side or within the enclosure of the main disconnecting means for separate buildings as provided in 250.32(B)
(3) On the supply side or within the enclosure of the main disconnecting means or overcurrent devices of a separately derived system where permitted by 250.30(A)(1)
(B) Load-Side Equipment. Except as permitted in 250.30(A)(1) and 250.32(B), a grounded circuit conductor shall not be used for grounding non?current-carrying metal parts of equipment on the load side of the service disconnecting means or on the load side of a separately derived system disconnecting means or the overcurrent devices for a separately derived system not having a main disconnecting means.
Exception No. 2: It shall be permissible to ground meter enclosures by connection to the grounded circuit conductor on the load side of the service disconnect if
(a) No service ground-fault protection is installed, and
(b) All meter enclosures are located near the service disconnecting means, and
(c) The size of the grounded circuit conductor is not smaller than the size specified in Table 250.122 for equipment grounding conductors.
 
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