neutral wire on multi conductor 208/120 3 phase receptical circuit

[Michael Schneider]

If you have a 208/120,3 phase 4 conductor circuit and the circuit is unbalanced there is current on the neutral conductor. IF you use 3 individual breakers and one neutral, and you turn one breaker off there, will be current on the neutral conductor. If you are working on the circuit you shut off, there will be current on the neutral conductor. Is this correct and how do you prevent this from happening if it is correct. Must you turn off all 3 breakers to work on any of the 3 curcuits.

 

[don_resqcapt19]

... Must you turn off all 3 breakers to work on any of the 3 curcuits.

Yes, and that is the reason for the rule in 210.4(B). That was a new rule in the 2008 code.

 

[cdcengineer]

Years ago as an apprentice I was hit by the neutral while working on a receptacle ckt. that was off. Little did I know at the time, that there was corridor fluorescent lighting on another breaker sharing the neutral. OUCH! Stuck me to it.

 

[infinity]

You need to shut off all of the circuits associated with the shared neutral at that point in the circuit. This could mean shutting off two or three circuits. If you're at a point where the neutral is only supplying one circuit then only that circuit needs to be shut off.