Phantom Power Water and Snakes

[DTV-Engineer]

Originally Posted by technerd

...Amp racks hidden in the back of stages are forever wired on different phases from the front of house gear. You can loose some members that way!

I'll agree with most everything except this. Good electrical distribution practice divides loads -- especially heavy loads -- equally among the three phases, because this minimizes neutral currents at the service equipment (i.e., breaker panel) and therefore minimizes the voltage potential between neutral and ground. In a larger system with multiple power amps, it's quite common to find the amps purposefully fed from different legs of the three-phase from the same breaker panel.

So long as your AC is wired according to code, phase has nothing to do with safety. In the worst case, even if you have a backstage amp powered from one leg from one breaker panel, and a stage outlet running on a different leg from a different breaker panel, you might have problems with hum... but it still won't be a safety issue.

-- Jeff

[waynehoskins]

Originally Posted by DTV-Engineer

I'll agree with most everything except this. Good electrical distribution practice divides loads -- especially heavy loads -- equally among the three phases, because this minimizes neutral currents at the service equipment (i.e., breaker panel) and therefore minimizes the voltage potential between neutral and ground. In a larger system with multiple power amps, it's quite common to find the amps purposefully fed from different legs of the three-phase from the same breaker panel.

So long as your AC is wired according to code, phase has nothing to do with safety. In the worst case, even if you have a backstage amp powered from one leg from one breaker panel, and a stage outlet running on a different leg from a different breaker panel, you might have problems with hum... but it still won't be a safety issue.

-- Jeff

In fact, my amp rack at the church is purposefully balanced across three phases. Absolutely no hum problems resulting from that. In large installs, that's pretty much the norm, to balance the load on the trafo. Or in a stadium gig, to balance the genny.