Query about meter stack

[katwalatapan]

Hello,

I have a query concerning selection of compatible meter stack. The multi-unit residential facility is fed via 3-phase, 4W, 120/208V, 400A main electrical service. Each apartment unit has a 100A, 1-phase, 3W, 120/208V electrical panel and the facility has 150A, 3-phase, 4W, 120/208V house panel. Each apartment unit as well as the facility is to be separately metered for electrical consumption.

I wanted to inquire if the best way to separately meter the apartment units and house panel, is to feed the main electrical service to a 400A, 3-phase, 120/208V meter stack, where apartment units have 100/125A, 4-Jaw, combination meter socket c/w 100A, 2-Pole breaker and a 200A, 13-Jaw, combination meter socket c/w 150A, 3-Pole breaker. The line side of the meter stack would also have a 400A, 3-phase, 4W, 120/208V main disconnect switch. OR,

Would it be best to split the 400A, 3-phase, 4W, 120/208V main electrical service via splitter box into 150A, 3-phase, 4W, 120/208V for house panel and 250A, 1-phase, 3W, 120/208V for apartment units. The 150A, 3-phase could then be metered separately via single, 7-Jaw, utility meter and the 250A, 1-phase for apartment units could be measured via meter stack with individual 100A, 4-Jaw utility meter.

I'd appreciate your comments on the above scenario.

Thank you.

 

[davidbeach]

What does the local utility have to say? It will be their meters, it doesn't matter what anybody else says.

 

[waross]

You will need at a minimum, 5 jaw meters. A single phase meter will see the 208 volts and assume that the single phase voltage is 208/2 = 104 Volts rather than the actual 120 Volts. The metering of all 120 Volt loads will be low by a factor of 104V/120V or 87%.
Been there done that.
A customer used 4 jaw meters to meter 120/208 Volt shore power sold to fishing boats. He couldn't understand why he was losing money.

Bill
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"Why not the best?"
Jimmy Carter

 

[katwalatapan]

Thank you very much for your responses.

I will approach the utility for their approved method. I wanted to inquire if a meter stack could have both 1-phase as well as 3-phase meter sockets installed in them OR would I have to install a splitter to separte the 1-phase and 3-phase meters.

 

[waross]

Why?? 120/208 Volts is not single phase. It is two out of three phases. You can't meter 120/208 Volts with a four jaw single phase meter.
Your local utility will have standards. Meter stacks are often custom assembled and mixing meter bases should not be a problem. In any event, 120/208 Volts may be metered with a full three phase meter.

I will approach the utility for their approved method.

That is the way to go.
I will be very surprised if you need a splitter.
The last stack I spec'ed had a mix of 100 Amp and 200 Amp meter sockets. I worked with the builder and basically spec'ed each section of the stack.
If your supplier has a problem delivering a stack with mixed bases, look for another supplier. Check the Yellow Pages for panel builders.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[katwalatapan]

Thank you very much for the responses.