House load metering on Residential Switchboard

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Kartracer087

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Consulting Engineer
OK, here is the situation:

You have a switchboard (lets say 2000A) and its fed from a utility transformer at 480Y/277V. The service conductors enter the switchboard and terminate in a 2000A main device. The main device feeds a 1000A bus duct which feeds dry type transformers. These transformers feed meter centers for apartment tenant units. Is it possible to add on another section to this switchboard and power about 600A worth of house loads? How would you meter that, would you simply use a separate section in the switchboard with a utility CT compartment and 600A circuit breaker? Or, would you generally be required to have the house loads on a separate service entrance?

Thanks.
 
I don' know of any requirement for separate service entrance as long as you have adequate capacity presently.
I would first discuss it with the switchboard manufacturer rep to see what's available.
 
You need to talk to the poco about what meter they want first. I've seen a poco not like the ct built in switchgear. They have a list of approved meters in their book.
 
I agree you definitely need to discuss with POCO.
Locally, any sub-metering is highly restricted.
 
Thanks for the reply guys.

Yes, I have looked at the requirements from the POCO, and they simply want a NEMA CT compartment in the switchboard for any meter above 2000A. The utility does not require EUSERC type metering compartments. I just was wondering if it is actually possible to use the same service and switchboard to feed both the tenant riser bus (the separately metered condo units) and the house panels for hallway lighting, the boilers, motors, and pumps for the general spaces in the building. I have done a little research and all the projects I've found have the house loads on a separate set of service entrance conductors from the tenant bus service entrance conductors. Most, then, have a switchboard for the tenants and a separate switchboard for house loads. It is much more convenient from a space consideration to have everything served from one set of service conductors and through one switchboard.

If this wouldn't be possible, then the other option would simply be to have a separate set of conductors from the service transformer routed to a transocket meter enclosure which is then connected to the house switchboard (separate from tenant switchboard).
 
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The only reason I've seen separate service entrances is cost. Two 2000 amp services usually cost less than 1 4000 amp service.
 
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