Adding a second meter to a 400amp commercial service

[GerryB]

How would you add a second meter. It is two store fronts, 400 amps in conduit coming into a CT cabinet, then a trough from the cabinet and panels off that. There is also a conduit from the CT cabinet to a meter and the meter has a terminal block in it with a lot of smaller wires to it. So this meter is reading the entire load. We want to break off the second store panel and meter it, but it has to be utility approved. (no emon-demon)

 

[GoldDigger]

How would you add a second meter. It is two store fronts, 400 amps in conduit coming into a CT cabinet, then a trough from the cabinet and panels off that. There is also a conduit from the CT cabinet to a meter and the meter has a terminal block in it with a lot of smaller wires to it. So this meter is reading the entire load. We want to break off the second store panel and meter it, but it has to be utility approved. (no emon-demon)

Since the meter uses CT and potential wires instead of pass-through you will at a minimum need to get additional CTs installed on what are now the feeders to the two store fronts instead of the service wires.
If the two customers do not have separate wires at the CT cabinet going to their own panels you have a potentially very big job ahead of you.
The first step is to see just what POCO will accept and/or do themselves to split the service billing.
Unless the two storefronts are fire barriered enough to allow them to count as separate buildings, the code may not allow two independent services, but if POCO is willing to call it one set of service conductors supplying two customers it could fly.

It sounds like you currently have two panels which are together acting as the service disconnect, so you are probably OK there.

 

[GerryB]

Since the meter uses CT and potential wires instead of pass-through you will at a minimum need to get additional CTs installed on what are now the feeders to the two store fronts instead of the service wires.
If the two customers do not have separate wires at the CT cabinet going to their own panels you have a potentially very big job ahead of you.
The first step is to see just what POCO will accept and/or do themselves to split the service billing.
Unless the two storefronts are fire barriered enough to allow them to count as separate buildings, the code may not allow two independent services, but if POCO is willing to call it one set of service conductors supplying two customers it could fly.

It sounds like you currently have two panels which are together acting as the service disconnect, so you are probably OK there.

Thanks GoldDigger, so if there are not separate feeders then I could probably install double lugs to make separate feeders. Everything I described in inside the building, outside is just an LB and a 4" riser conduit. The electrician who was telling me about the job was talking about putting a 2 gang meter socket outside and rewiring from there. I don't know if he knows there is a CT cabinet. If that can be done can the CT cabinet then be be eliminated or bypassed.

 

[GoldDigger]

Thanks GoldDigger, so if there are not separate feeders then I could probably install double lugs to make separate feeders. Everything I described in inside the building, outside is just an LB and a 4" riser conduit. The electrician who was telling me about the job was talking about putting a 2 gang meter socket outside and rewiring from there. I don't know if he knows there is a CT cabinet. If that can be done can the CT cabinet then be be eliminated or bypassed.

POCO chose to use CTs for a reason, probably the size of the service. If they split it into two they may each be small enough for in line metering. But the only way to know for sure is to ask POCO. The sooner the better so they can assign an engineer to the question.

If there is no outside main breaker or fused disconnect, are both panels close enough to the point where the service conductors enter the building to satisfy the AHJ?
Are the panels in a common electrical room or in what will become an individual storefront's space?

Lot's of other questions I don't know to ask yet.

 

[GerryB]

POCO chose to use CTs for a reason, probably the size of the service. If they split it into two they may each be small enough for in line metering. But the only way to know for sure is to ask POCO. The sooner the better so they can assign an engineer to the question.

If there is no outside main breaker or fused disconnect, are both panels close enough to the point where the service conductors enter the building to satisfy the AHJ?
Are the panels in a common electrical room or in what will become an individual storefront's space?

Lot's of other questions I don't know to ask yet.

Thanks again, very interesting. The panels would be close enough, electric room inside, could always pipe a few feet outside the building also. The main disconnect for the second store would be in this electric room in the first store which is how it is now with a sub panel in the second store. I will get more info, right now I am wondering which method is more work, money, etc. BTW this is a one story building about a 100' long with the service at one end.

 

[GoldDigger]

Thanks again, very interesting. The panels would be close enough, electric room inside, could always pipe a few feet outside the building also. The main disconnect for the second store would be in this electric room in the first store which is how it is now with a sub panel in the second store. I will get more info, right now I am wondering which method is more work, money, etc. BTW this is a one story building about a 100' long with the service at one end.

I don't think that the code cares whether the Store 2 main disconnect is in Store 1's locked space, but the tenants may have an issue with it.
If that is a problem, putting the #2 main disconnect outside and then running the wire inside to take the same feeder to the existing subpanel, just wihtout going through the #1 main panel should take care of it.
Note that you could not mix the post-disconnect #2 feeder with the pre-disconnect #1 service conductors in the same raceway entering the building. That would not be allowed by code.
If you do not want to make another hole, you could put both disconnects outside and make both interior panels sub panels. (Separating neutral and ground, of course.)

 

[electrofelon]

POCO chose to use CTs for a reason, probably the size of the service. If they split it into two they may each be small enough for in line metering. But the only way to know for sure is to ask POCO. The sooner the better so they can assign an engineer to the question.

I came across a very similar situation as the OP. Existing was 400 amp, 277/480, CT metered. Client wanted two meters. POCO let me do two 200 amp self contained (I used two singles, not sure if they make a 2 gang for 480 self contained). I got the added benefit of avoiding the City of Seattle plan review requirement for equipment 400 amps and over