I'd like to point out one error in Alberts post. It has two do with two 120volt phases one row on the left side one row on the right.
A panel is configured so that a (full size) breaker and the breaker directly underneath it are on opposite phases. That way a two-pole breaker can be plugged into two spaces right next to each other (or one on top of the other) producing 240volts.
To truly isolate one half of a residential panel 120/240 volt. You would have to configure your breakers top to bottom skipping every other space.
I hope that makes sense. In all practicality there is no possible way to isolate any one phase for audio unless you have a three-phase panel with no 3-phase loads present in that panel.
My best advise is to always pull a dedicated neutral (white wire) with every hot. In addition add an isolated ground and I.G. receptacles
While I'm on the subject I'd like to mention that there is no such thing as two phase power. 120/240 is derived from a single transformer and is refered to as single phase power in the electrical trade in general.
3 phase power can only be 120/208, 277/480, or 120/240 with a high leg(Not very common except where lots of motors are present) These are standard 3 phase voltages used in the USA
A panel is configured so that a (full size) breaker and the breaker directly underneath it are on opposite phases. That way a two-pole breaker can be plugged into two spaces right next to each other (or one on top of the other) producing 240volts.
To truly isolate one half of a residential panel 120/240 volt. You would have to configure your breakers top to bottom skipping every other space.
I hope that makes sense. In all practicality there is no possible way to isolate any one phase for audio unless you have a three-phase panel with no 3-phase loads present in that panel.
My best advise is to always pull a dedicated neutral (white wire) with every hot. In addition add an isolated ground and I.G. receptacles
While I'm on the subject I'd like to mention that there is no such thing as two phase power. 120/240 is derived from a single transformer and is refered to as single phase power in the electrical trade in general.
3 phase power can only be 120/208, 277/480, or 120/240 with a high leg(Not very common except where lots of motors are present) These are standard 3 phase voltages used in the USA