sizing transformers on multi meter services

[SHOCKY61]

i have a 480 volt 3 ph service with a;800 amp main disconnect 5 metered grouped /multimeter module. This grouped meter module has (4) 200 amp meters and disconnect( for individual office rentals ) and (1) 125 amp meter and disconnect( for house lights and outdoor area lights ) Do i size the trans formers using the service amperage of 800 amps in the calcalation formula or the load center amps of 200 when stepping down the voltage to 208v / 120v to each office

 

[Smart $]

i have a 480 volt 3 ph service with a;800 amp main disconnect 5 metered grouped /multimeter module. This grouped meter module has (4) 200 amp meters and disconnect( for individual office rentals ) and (1) 125 amp meter and disconnect( for house lights and outdoor area lights ) Do i size the trans formers using the service amperage of 800 amps in the calcalation formula or the load center amps of 200 when stepping down the voltage to 208v / 120v to each office

Your description is a little vague on where the transformers are located. Having used the plural term, I'll assume they are load side of the meter/disconnects. To be 100% compliant with the NEC, you would have to do an Article 220 load calculation, and take the result into consideration, among any other considerations. After that you have a basis for design decisions. For example, being rental space and subject to tenant changes, it may be more desirable to size each transformer to the available VA for its primary.

 

[Smart $]

Another determining factor might be that tenant loads have yet to be determined. You'd obviously not be able to do a load calculation... it would have to be a load speculation and I imagine that has already been done.