[mallen9595]

Thanks for the reply and for the advice. I'm familiar with this configuration, and I do shut off the power except to test voltages. When the breaker is open, there is no voltage anywhere. But when it's closed, there is 119V on the supply line to the light box. Connected to the supply hot is the black lead to the wall switch loop, with the white lead (colored black, since it's hot) as the return leg. When the wall switch is closed, there is 119V across the return leg (from the switch) and the neutral, which is as it should be. But when the switch is off, there is 27-30V.

I also get some really odd voltages which I didn't mention before. Originally, just to keep things simple, I mentioned just what was happening at each lightbox, with nothing else connected. But there are actually three lights in this installation, each with a separate switch loop, and feeds from the main supply going between them. I've tried disconnecting all the switches and I get 119V on the feed at all three light fixtures. Everything's ok so far. And when I connect one of the three wall switches in a switch loop configuration (remember, each switch powers one light and nothing else), I get the aforementioned voltages. Everything is still okay except the possibly phantom 30V when the switch is open. Now, here's the problem: When I start connecting in the other switches, I get voltage drops across the main. I don't remember if the switches have to be open or closed, but I get 90V with two switch loops connected, and 60V with all three connected. I have even tried replacing the switches themselves, but this still happens. I get 119V at outlets in this house regardless, although they are on another circuit. FWIW, I am using two different meters, so I can't blame the meter.

The 30V "phantom" on each open switch when it's open is very steady. Next week is the next opportunity I will have to check this circuit, and I will try an analog meter as you suggested and also look at the FAQ. But I can't explain the apparently voltage drop by having two or more switches tied into the circuit. I've never seen this before. That's why I think there's more than phantom voltage at work here. Also, this house has abnormally high energy bills, and I wonder if there's some kind of leak contributing to this mess. Although the wiring in this house is all grounded, it is 50 years old.