Meter, transformer, ac panel upgrade part or all

[Bigbadlou]

Hello, I’m looking into some AC Panel upgrades, on a site on a 2 story roof. On the first floor is where utility has the meter, the meter panel is single phase 480/277v, with 3 legs in only 2- legs out, each leg has a 100 amp fuse. On the roof is where these two legs go to a 100 amp disconnect to a 25 kva step down 120-240 transformer. The wire is #6, conduit is 1”. From transformer to ac panel wire is #2, 100 amp panel. Custumer wants a 200 amp ac panel for 2 cabinets which take a 100 amp breaker, but there load is only 30 amps each. How would I know if the dissconnect is protecting the transformer or ac panel or both Would I have to upgrade only the secondary side or both primary and secondary. Would I have to put a 35.5, 50 kva transformer and would I have to go as far back as upgrading the meter 100 amp fuses per leg.

Thank you if you can help, I’m so confused.
Bigbadlou

 

[Dennis Alwon]

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