Need help with New 400 or 600 amp Service

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W

Wizard

Member
Location
New Orleans
I’m installing a service for a new car wash. The car wash came with prints for the wiring for the car wash itself but not for the service. The building was previously a car wash but now they are installing a bigger system.

The service is 480 volt three phase. The installer wants a 400 amp breaker for his motor control center, a 200 amp breaker for a 480/277 200 amp panel and another 200 amp breaker for a step down transformer.

The total connected load is 318 amps, and the total building will be 352kw. I sent this to the power company and they said the most they will give me is 400 (320) amp meter system.

I have to put a 400 amp disconnect before and after the meter to satisfy the power company.

All that being said my question is do you think I can feed a 400 amp indoor panel board and put in a 400 breaker for the motor control center and the two 200 amp breaker? Or should I go to the 600 amp panel board ? If I go to the 600 amp then I have to feed it with bigger wire when it is still fused at 400 amps at the disconnect.

Any help would be appreciated.

I really don’t want to pay an engineer
 
kwired

kwired

Electron manager
Location
NE Nebraska
I agree with Tom.

I do have to ask what is on the stepdown transformer. 200 amp breaker seems overkill if it is just for some miscellaneous 120 volt loads. 10 or 15 kVA seems would be sufficient if just misc 120 volt loads and could easily be on less then 50 amp breaker.
 
kwired

kwired

Electron manager
Location
NE Nebraska
ptonsparky said:
How did you come up with 390? I come up with 424.

OP does need to verify his total load.
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Same here. If adding another 318 amps 320 meter doesn't seem right at all, going to have to try to cram 750+ amps of conductors into something designed for 400 amps:blink:
 
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