380volt 266KW how many amps?

volts = watts divided by amps

amps = watts divided by volts

watts = amps times volts

so 266,000 watts divided by 380 volts = 700 amps

and I might also point out that whatever it is you are talking about is very dangerous and can kill you in less than a heartbeat. I'd be sure to talk with an electrician if I were you if you plan on going anywhere near that.