grounding of meter center

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kentpowell

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I am installing a new meter center. There is a 1600Amp main switch coming in from the power company's transformer. The main switch has a four buss bars--three phases and a neutral--which feed thru to the meter stacks on each side.
There are 3 stacks of 4 meters each on each side of this main switch. Beside each meter is an 100Amp breaker to serve the individual user.

I think I should be bonding at the Main switch; then seperating the earth ground and the grounded neutral conductor in the meter stacks.
Since the equipment has no provision for earth grounding in the meter stacks ( as provided by the manufacturer), it gives me pause to wonder if I am correct?
 
Re: grounding of meter center

Originally posted by kentpowell:
There is a 1600Amp main switch coming in from the power company's transformer.
Click to expand...
Stop there, that is very likely the service disconect (It could be a 'meter disconect').

If it is the service disconect you are required to bond there. Beyond that point the neutral and grounds must remain separate as you suspected.

I am sure there is a GEC terminal and bonding strap located in (or shipped with) the 1,600 amp switch.

I think I should be bonding at the Main switch; then seperating the earth ground and the grounded neutral conductor in the meter stacks
Click to expand...
I would not change anything in the meter stacks unless specifically directed to in the instructions.

[ January 19, 2006, 06:38 AM: Message edited by: iwire ]
 
Re: grounding of meter center

Bob,
Does this not sound a whole lot like one of the "modular meter centers". Its been a while since I've worked on one, but I believe the whole assembly is considered service equipment with a common neutral/ground buss for load taps. I can't put my finger on where this is addressed in the Code, pehaps Exception 2 for 250.142(B).

In any event I agree with your last comment on not changing anything.
 
Re: grounding of meter center

2005 NEC Sec. 250.142(B) Exception #2 states it shall be permissible to ground meter enclosures by connection to the grounded circuit conductor on the load side of the service disconnect where there is no service ground-fault protection, all meter socket enclosures are located immediately adjacent to the service disconnecting means and the size of the grounded circuit conductor is not smaller than the size specified in Table 250.122 for equipment grounding conductors.
 
Re: grounding of meter center

Beside each meter is the 100Amp breaker that will serve to disconnect each individual unit's panel; the breaker is 3 phase. There is also a neutral connection (lug) available for each breaker.

But when I run the cable out of the meter stack to the inviduals units, I need to run an earth ground with it. There is no place to do that in the stack. And yes the bonding jumper and a ground bar shipped with the 1600Amp main breaker.

I'm thinking I need to run a separated gound (bar) to each meter stack from the ground bar in the 1600Amp main so as to have a point to land the earth ground of the cable going out of the meter stack to the units.

Or do I just not separate the grounded and grounding conducts in the panel? and that just doesn't set right in my mind. Any more than installing a separate earth ground at each panel?

I appreciate your comments, thanks!
 
Re: grounding of meter center

Kent, the last meter center I used, a QO, had a row of EGC logs at the bottom of the stack, which I relocated to the top because thet's how the SER's went out.

Check the bottom section of the mster/breaker compartments, and all around the inside. I find it hard to believe that the manufacturer didn't include any lugs.
 
Re: grounding of meter center

Kent,

I believe you are using the term "earth ground" for what the NEC calls the "equipment grounding conductor". I mention this, because using the term "earth ground" adds to the mispreception that the purpose of the conductor is to carry fault current to the earth, when in fact, its purpose if to carry fault current to the service disconnect where it can follow the service neutral back to the power source (the utility transformer)
 
Re: grounding of meter center

Cool Post :cool: luv this forum,

I have exactly what this post is saying. A modular meter center, Except for a few minor things.
-The service Main ( not switch ) is 800amp
-Beside each of 5 meters is a 200amp 3ph. Circuit Breaker
I have to agree with augie47 that the whole assembly would be considered service equipment since the six grouped disconnect rule is in place.

[ February 28, 2006, 11:21 PM: Message edited by: mjc ]
 
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