when we change voltage

[kimrichi]

let us say we have a range and an oven at 115/230
if we change the range and feeder to be 120/208 three phase
how we calcualate feeder amp in this case

 

[kwired]

let us say we have a range and an oven at 115/230
if we change the range and feeder to be 120/208 three phase
how we calcualate feeder amp in this case

Anything connected line to neutral is still the same (120 volts)

Anything resistive that operates at 240 volts will have a decreased output of roughly 75% @ 208 of what it uses at 240. (1000 watt @ 240 / 750 watt @ 208)

Motors will draw more current @ 208 than they do @ 240. Roughly 10% more most of the time. Total VA will remain about the same for a motor load.