Sizing Service conductors for multi metering

Status
Not open for further replies.
H

howardrichman

Senior Member
I'll be installing two single phase services on a detached garage. Presently both services are overhead, and one is 200 amp and is on a house, and the other is 200 amp on the detached garage. I'll be moving these services underground and installing two meters on the detached garage to rid the overhead services. I may upgrade the house service to 300 amp w/ a generator. I'll be installing the feed conductors from a given pole underground to a troth feeding both meters; the 200 for the garage, and 300 for the house. The 300 amp for the house will be trenched from the detached garage. My question is what size conductors ill be permitted to feed the two meters. Is it determined by a load calculation, or by a percentage reduction in sizing feed conductors? I'd rather not, but I could reduce the garage service size to 100 amp if necessary to reduce service conductors. Does the feed conductors have to match the meter sizing? Does it mater if it's residential or commercial?


HR...
 
howardrichman said:
My question is what size conductors ill be permitted to feed the two meters. Is it determined by a load calculation, or by a percentage reduction in sizing feed conductors?
Click to expand...
The minimum size conductors are determined by a load calculation... with loads of both "services" combined. I say "services" because technically, with a single service lateral, it is only one service with two service entrances, two meters, and two service disconnecting means. The existing sounds more like two services.


howardrichman said:
... Does the feed conductors have to match the meter sizing? ...
Click to expand...
Not really. Both have to have a rating greater than the calculated load factored for continuous loading.


howardrichman said:
... Does it mater if it's residential or commercial? ...
Click to expand...
No.
 
Thanks for reply. I was figuring on installing 500 MCM copper, cause I know the load is mostly on the house. I'll have to bring the question to the local inspector w/ load calcs. and go that route. Also; I'll be installing a 300 amp transfer switch on the house and use multi tap lugs, run 100 and 200 amp se cables into two panels in basement of the house. Not sure if those panels need mains cause of the imbalance of protection of the 300 amp main breaker in the transfer switch.


HR...
 
howardrichman said:
My question is what size conductors ill be permitted to feed the two meters.
Click to expand...

At what point do you plan to get the power company involved? The overwhelming majority of the time, what's upstream of the meter is owned and sized by the poco. As the poco, we would usually tell you what size pipe to install for us, but we would specify, supply, install and terminate the wire up to the meter. For a typical 2,000 square foot house, all electric with a 200 amp service, I would usually call for 2/0 aluminum unless the run was overly long (>150 feet maybe). A lot of the guys would call for 1/0 aluminum for such a house, but that always seemed a bit too skinny to me.
 
And if the OP, for some reason, has a disconnect upstream of both meters, it is probably not considered to be the service disconnect for the two buildings.
 
Status
Not open for further replies.
Top