I have 6 thwwn feeding from 50 amp breaker 3 phase. Supply is 208 volts and unit is designed to pull 38 amp. Feeding 240 volts to unit causes a reading of 42 amps. There is ine high leg.

Could you be a bit more specific with your question?

What's your question??
The resistance elements will draw more at a higher voltage.

Just curious, but on a 120/208 system, where is the 240 Volts coming from?

For the record, my previous post was just for grins.