AC Power Question

As my questions should suggest, I understand how these circuits work. What I don’t understand is how the load on one phase can influence the current on the other phase, unless there is something wrong with the electric service in the first place.

Shared neutrals are absolutely allowed under NEC and I see no reason to avoid them.

sleepwalker65

... they used the other leg on that 14/3 for lighting in the first floor. Every time the clothes washer was running and switched cycles, the lights would flare. No wonder they would burn out so often, with all that excess back-current!

Will you please explain what "back-current" is? If you have a 14-3 cable, then each of the hot wires come from different legs of your service, correct? (After all, that's why they can share a neutral.) Please explain how a changing load on one leg can influence the voltage on the other leg.

If your 14-3 cable is connected to the same phase (leg) of your AC service, that's a code violation because of the shared neutral, no?

I think dedicated, de-rated, 20A lines are the way to go. If you think you might need two lines, then get three. If you think you need three, get four. It’s less expensive and invasive to do it all at once.

I am also a major believer in getting an electrical construction permit before commencing work. Your local electrical inspector is your inexpensive QC against shoddy work - we’ve seen examples of that here on Audiogon - or a simple error. And the approved permits can be useful when you it’s time to sell your house.

I have dedicated lines on both legs of my service, and don’t see or hear a difference between them. YMMV. My system benefits from isolation transformers and power conditioning all around, including on amplifiers. They make a huge difference, and all for the better.

While you’re doing this work, it’s wise to check the other aspects of your power. Are all connections clean and tight? Is your grounding up to current code? And here’s the most overlooked detail, imo: Can your electric utility deliver sufficient current? If you think your "200A service" means that your utility can deliver 200A of current, you are almost certainly mistaken. Do your lights dim substantially when you turn on your power amp? That can be a clue to current delivery issues.