How many hours does a 500W electric oven consume 1 kilowatt hour, and how many hours can a 100W lamp work

How many hours does a 500W electric oven consume 1 kilowatt hour, and how many hours can a 100W lamp work

1kw·h=3600000J
From w = Pt, t = w / P = 3600000j / 500W = 7200s
7200s=2h
1kw·h=3600000J
From w = Pt, t = w / P = 3600000j / 100W = 36000s
36000s=10h

The air switch of three-phase electricity is 100A. Is it the sum of the currents of three-phase electricity or the current of each phase 100A

When the air switch of three-phase electricity is 100A, the current of each phase is 100A

Why is the three-phase electricity measured after the air switch? One group of line voltage is 380V, and the other two groups are 220V

Wiring error, phase line and zero line may be mixed