AC Polarity

Wiring is speced by our National Electric Code. However, you have some options. I recommend a dedicated 20 amp isolated ground circuit to a quad (double duplex) outlet. Dedicated means that there are no other faceplates on that circuit breaker (it is common to wire up more than one faceplate to one circuit). 20 amp means the breaker and wire used can carry more current than a typical 15 amp circuit. Isolation grounding means that a different wire type is used to carry the back-box ground to another grounding point on the breaker box. This usually provides better isolation from noise. A single circuit such as this in my home in Philadelphia cost about $100.

The short slot is "hot".

There's only 1 way to wire an outlet - white to silver screw, black to brass screw, ground to ground screw (and to box if metal). Put in a dedicated line for audio. Buy the orange hospital grade outlets and use heavy guage wire (#12 minimum, #10 better). Try to situate the audio circuit in the circuit breaker box at the top (near the source wires) and definitely before any heavy draw circuits especially those that feed motors. Even better - have the electrician run a dedicated ground field for the dedicated line(s). Multiple dedicated audio lines should be on the same phase (if you don't need 220) - normally, to wire 220, you run wires from 2 adjacent breakers. If you test across the 2 points in the service panel with a voltmeter, it will read 220V. if you skip a spot and test across, say breaker point #1 and #3, the voltmeter should read 0V. That's what I mean by same phase. Use #1 and #3 or other combinations that read 0V between them. This is work for an electrician unless you really know what you're doing. What I'm saying here is my understanding based on reading and conversations. I'm not an authority.