330 watts would be about right for ONE "250 watt" halide potentially, but not two Radiums.
I think I may have what you're testing confused in my brain.
(If @BoomCorals is right, you should expect both brands to consume very close to the same power.)
The amps I got were from the Hamilton’s not the radium. 2 Hamilton bulbs and I was getting 3 amps not the 4.5 I should be.


