How big is the main line of the hotel's 30 rooms?

The pow supply is preferably 380 volts. In this way, the electric energy can be used more reasonably and the load of the transformer can be distributed reasonably.

For a * * * 30 rooms, it is suggested to use one phase power supply for every ten rooms, so that the three-phase power supply is just distributed to 30 rooms. Then the current should be 5 kilowatts, and the single-phase electricity 1 kilowatt should be distributed according to 5 amps per watt.