jmellc
Senior Member
- Location
- Durham, NC
- Occupation
- Facility Maintenance Tech. Licensed Electrician
Looking at a job for my church, possibly having POCO set a new transformer, feeding a service for several office trailers. 1 trailer for sure has a 200A panel, 1 has a 100A panel. Other 2 are in future, probably no more than 200A each.
Meeting Sat with guy from POCO, until then I can't open existing transformer cabinet to check things out.
Our existing transformer has a 3 phase meter on a short post right next to it. I'm sure the CT's are inside the transformer. The meter base is too small for them. It is a 480, probably has capacity for the needs, but we'd have to set a 208 txf next to it, and cut across driveway, etc. Same with MDP in building. Plenty of space, but it's 480 & we don't have much space for txf there.
My thinking is having POCO set a txf at a spot within 100' where it has spare pedestals already. Set a 3 phase meter next to it and ditch over to approx ctr of trailer sites. Set up a stand there with 600A disconnect & large j box or line gutter. Parallel feed it with 2 350 MCM's & tap for each trailer with a breaker enclosure, trench out to each trailer as it arrives. Use Polaris lugs to splice taps. Drive 2 ground rods at stand. Feed 1 phase loads with AB, BC, CA, AB. I f I keep the known lighter load on AB, it should keep the loads approx equal, as C is 1 less load to start with.
Anyone see problems here? Am I overlooking anything?
My supply houses so far only have a 300A meter base. I thought 3 phase meter bases were somewhat standard, as ct's are used to give them partial current. I believe our main breaker in MDP is 1,500A, have to check again. Are
most transformer cabinets large enough to mount CT's inside, as our existing one appears to be?
Meeting Sat with guy from POCO, until then I can't open existing transformer cabinet to check things out.
Our existing transformer has a 3 phase meter on a short post right next to it. I'm sure the CT's are inside the transformer. The meter base is too small for them. It is a 480, probably has capacity for the needs, but we'd have to set a 208 txf next to it, and cut across driveway, etc. Same with MDP in building. Plenty of space, but it's 480 & we don't have much space for txf there.
My thinking is having POCO set a txf at a spot within 100' where it has spare pedestals already. Set a 3 phase meter next to it and ditch over to approx ctr of trailer sites. Set up a stand there with 600A disconnect & large j box or line gutter. Parallel feed it with 2 350 MCM's & tap for each trailer with a breaker enclosure, trench out to each trailer as it arrives. Use Polaris lugs to splice taps. Drive 2 ground rods at stand. Feed 1 phase loads with AB, BC, CA, AB. I f I keep the known lighter load on AB, it should keep the loads approx equal, as C is 1 less load to start with.
Anyone see problems here? Am I overlooking anything?
My supply houses so far only have a 300A meter base. I thought 3 phase meter bases were somewhat standard, as ct's are used to give them partial current. I believe our main breaker in MDP is 1,500A, have to check again. Are
most transformer cabinets large enough to mount CT's inside, as our existing one appears to be?
