what system is it

[zyhml]

in another word, what part of code shall i use? plant got feeder 10KV(3 wires) from serving utility, then in the substation two 10KV/380V transformer are used to distribute power to equipments in site. is it service or separately derived system?

 

[iwire]

If you are under the NEC the 'Service' starts at the service point and ends at the service disconnect.

Where that is in your situation is a question for the serving utility.

Who owns and controls the substation?

 

[zyhml]

your response is very appreciated. client owned the substation