Lighting contactor

[hillbilly1]

That makes absolutely no sense of course there’s gonna be faults on the load side if the contactor is stuck in a closed position regardless if the control wire is landed or not, what do you mean by a wrong tap from a different phase from the load side of another contractor it’s completely separated. That makes zero sense.

It means somebody has tapped two other circuits together with those two somewhere on the load side. It will not show up until you turn the power on, and all contactors are closed. Troubleshooting 101.

 

[Little Bill]

@Therealcrt
Is the circuit that is sharing the neutral (MWBC) always the two circuits that the contactors burn up and trip the breakers?
If so, it almost has to be the neutral is open causing 480V to hit the coils and destroy them.

Before burning up any more coils, check the neutral for continuity from panel to where it splits.

 

[mtnelect]

That's narrowing it down. That's what troubleshooting is, a process of elimination.

Now try disconnecting one wire at a time, or disconnect all and reconnect one at a time.

I call it the "Scientific Method" ... it's first one I always use !