I have a main service outside a building that feeds a trough an an?electrical room. from there, several meters for the individual units. The meters feed individual disconnects that in turn feed the panels in the units,grounds an neutrals are common in the existing disconnects inside the electrical room, as well as outside in the main.
When I questioned the installation I was told it was correct because there is a meter between the main and the disconnect...
any thoughts??
Is it legal to sepreate the grounded and grounding condutuctor in both the main disconnect on a building with mulitple meteres that service several disconnects for the individual units? I appologize If I'm am confusing you all I should have thought about the question instead of the situation.
I was told by the engineer that if you place a meter between the main and a disconnect that services a unit in a multi unit complex you are
creating a "new" main disconnect for that unit so it is legal to make grounds and neutrals common even thogh it is after the first means. I cant find that exception in the book
I don't know what the NEC rules are on this, but basic principles require that the grounded (neutral) conductor should be isolated from the equipment enclosures on the load side of the main disconnecting means.
The equipment enclosures should be bonded to the grounded (neutral) conductor at one point only, at the same point where the grounding electrode conductor is connected, in the main disconnecting means.
Note that this will require the meter sockets to be equiped with insulated neutral kits.
Your engineer may be correct after all.
After I wrote the post above, I did a little more research and came up with the sketch below, from a utility company website.
However, this sketch does not show the neutrals bonded to enclosures in the feeder disconnects.
Even though the diagram is from a POCO, I'm not sure it is NEC compliant.
Perhaps some of the code savvy guys would comment?
Ed
[ April 02, 2004, 10:13 AM: Message edited by: Ed MacLaren ]
Ed, the drawing is correct as long as the meters are near to the service disconnecting means. The drawing is wrong if the meters are not close. Additionally, the metering equipment is just that, not service equipment. The bottom line is that our cash register location doesn't affect the required grounding.
