sizing transformer

[Sahib]

One more issue. Suppose the transformer size is worked out. If the size of the OCPD for the transformer protection is smaller than the panels incomer circuit breakers (already provided), it could cause coordination problem.

 

[topgone]

One more issue. Suppose the transformer size is worked out. If the size of the OCPD for the transformer protection is smaller than the panels incomer circuit breakers (already provided), it could cause coordination problem.

Not gonna happen. The usual thing is to work from the bottom up.

 

[iwire]

Sorry I do not know how Iam violating NEC......

That is correct, you do not know so the best thing you can do for the OP is to shut up and observe.

 

[kwired]

One more issue. Suppose the transformer size is worked out. If the size of the OCPD for the transformer protection is smaller than the panels incomer circuit breakers (already provided), it could cause coordination problem.

Inconvenience is more likely the proper thing to call it. Unless these "trailers" are serving as a public safety command center or a 911 call center or something similar where keeping the power on is critical.