[BC] Re: [Pubtech] 3 phase power and audio

[PeterH5322]

>I had not heard of the preference for keeping all audio loads on the same
>phase of three phase power before. I'm guessing this is so leakage
>currents to ground are in phase so the chassis voltages on all devices are
>in phase, reducing ground loop currents or common mode voltages on analog
>inputs? Is that the reason for this preference?

Sounds right, but one solution would be to install a Topaz, or equal, 
isolation transformer, at appropriate places.

The secondaries of the Topazes will be "separately derived" circuits, so 
these would have to be grounded according to the rules for separately 
derived circuits.

Such a ground would be returned to a single, common point in the premises.

With such a ground, ground loops would be eliminated.

The Topazes I have provide 120 dB of isolation.

I have ones with conduit knock-outs, for permanent installations, and one 
which has a NEMA 5-20P and a 5-20R, for temporary installations.

This second one is usually used on the bench to provide more-or-less 
complete isolation from the devices under test and the power line hash.