Dedicated Power Lines

This is a good thread. I got help here a number of years ago when I had dedicated lines installed in my current room. A couple of anecdotal observations, while I am not an electrician and don't pretend such expertise:
1. I thought choosing one leg over another was about finding the side which had less noisy appliances, lighting, etc. connected to it.
2. I agree that we tend to over spec, given the amount of actual current drawn by our gear- thus, having separate dedicated lines to support amps, separate from front end electronics, etc. But, in my experience, using very high efficiency horns, I could hear low level grounding issues that I attributed to the 'difference' in separate lines, i.e., the 'Brits' tend to hook everything up to a single line and then use a distribution box in the room.
3. I like the idea of separating lines for analog and digital but if they are ultimately hooked up to either other through interconnects, i.e, a HT system that connects to the audio system, how much difference does that make? (My HT is entirely separate from the hi-fi and uses a 240 volt step down transformer to isolate it from an analog only hi-fi system).

1. I thought choosing one leg over another was about finding the side which had less noisy appliances, lighting, etc. connected to it.
06-24-13: Whart

There are those that follow that belief. Keep in mind when the house was originally wired 120V branch circuits for the kitchen, laundry, furnace, lighting loads, and whatever other possible loads were somewhat evenly divided, balanced, across L1 and L2 to neutral at the service panel.

In most cases our homes are fed from a utility power transformer with a split phase secondary winding. The way a split phase winding works only the 120V unbalanced load returns on the neutral conductor to the source, the utility transformer.

Example. Say L1 to neutral has total connected load of 20 amps for a given point in time. L2 to neutral has a total connected load of 10 amps at the same given point in time. Only 10 amps will return on the service neutral conductor to the source.
The remaining balanced 10 amps is in series across L1 and L2.

Example. Say both 120V L1 to neutral and L2 to neutral loads are exactly 20 amps each.... 0 amps will return on the service neutral conductor to the source, xfmr.
The two 20 amp 120V loads are in series with one another and are being fed by 240V.

Single phase power systems.

So, so much for trying to feed your audio equipment from one Line or the other because of noisy appliances/equipment.

I do believe it helps not to have dedicated branch circuit breakers that will feed audio equipment installed right next to breakers that feed noisy electrical appliances/equipment. Whether the noisy loads are 120V or 240V. A 240V load example would be the air conditioner condensing unit outside of the home.
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Jea48,
I finally did the test on the hots of my isolated power. Maybe I was lucky or the transformers just handle it but when I tested the 120V loads together 2 at a time they all read 0 volts.
lee