a 1000 watt light will use 5 a per hot leg, so x2 = 10 a, same as 120v. the power usage is the same.A 1000w light will use about 5a at 240v and about 10a at 120v.
a double 30 amp breaker is 30 amps per hot leg. 240v has 2 hot legs,120 volt has 1 hot leg. 240 allows you to run smaller wire and is less wear and tear on equipment. But a 1000 watts is a 1000 watts, doesn't matter what power is supplied to it.I understand that, but when you have a 240v 30a breaker it is still 30amps, not 60. Draw measured is just that.