Got a problem with a 3 phase voltage machine using 2 compressors for heating. When the isolator is in the open position - that is off :-) I get the normal phase to phase voltage of 400V. As soon as I switch the isolator on the machine's phase failure prevents the machine from turning on as the voltage is not the same across the phases. When I measure I get 500 on one then 270 on another. These are really weird voltages I'm getting. I have swapped the phase conductors around which did not help. Could the phase failure be faulty? Any help would be awesome!