If any of these are 3-wire switches, I would start by analyzing whether the correct wire was on the common. If you replaced switches, you can't necessarily go by the physical positions of the screws.

The 10-15 volts is probably stray voltage, and would be zero if there was a load on the wire. Technically it is capacitive coupling from a nearby hot to this wire that is neither connected to hot, neutral, nor load.

That would go along with having the wires in the wrong order on a 3-wire switch.

Thanks so much Bill for your quick and extremely helpful reply. I'm finally back to tackle this after unexpectedly spending the day on the road. I'm sure you're right about me messing up the order of the wires.

I have two single-pole, 2-wire switches next to each other, controlling different lights. One of the lights has 3 wires with a red lead attached to 1 screw of the switch, and a jumper from the other screw to the 2nd switch. On the 2nd switch both screws have black wires attached.

Problem is that I cut the wires off the switches to move them and now obviously can't figure out how to put them back.

Do you have any suggestions based of the above?

Many thanks,
streamer

Oh, and 1 more thing I neglected to mention. The 2 white leads - one from each light - were tied together but I could swear that there was a third white wire tied to those 2 and pigtailed to ground. Am I hallucinating?

Thanks again,
s.

Yes I believe you were.
The whites (neutrals) should not have had a pigtail to ground.
Are you sure that here wasn't a ground wire from the grounding screw on the yoke attached to the box?
Both switches only have two screws, correct?
Does one have three screws?
How is the red attached to the second switch?
Something is not adding up here.
If they are single pole switches, the jumper may be the hot feed but you should only have two wires attached to the 2nd switch.
Three wires on the first switch makes sense (hot in, hot out to 2nd switch, and switch leg).

Both switches have 2 screws, for sure.

I'm up and running! Thank you both for the invaluable help in sorting this out. I reconnected the switches going by memory - with the bizarre white leads going to ground - and I regained juice to those 2 switches and the other rooms. Apparently the house was wired according to some medieval system. Go figure.

Now back to work - this was supposed to be only a minor part of a diy kitchen reno - not a 2-day glitch.

streamer

I reconnected the switches going by memory - with the bizarre white leads going to ground - and I regained juice to those 2 switches and the other rooms. Apparently the house was wired according to some medieval system.

I hate to whiz on anyone's victory parade, but if you got this to work by connecting the white neutrals to an equipment ground, then don a well-insulated suit of armor because medieval attire surely fits the occasion.

Sure it appears to work properly, but you've still got a problem, IMHO. Hmmm. The case of the missing neutral.

I'll second that one terribletom.
It sounds like a neutral got lost in the past and they are using the ground.
This can be a very hazardous situation and needs to be addressed before someone gets hurt.

Maybe this makes sense, or confuses the problem more. The light fixture was attached to the red and white wire while the 2 blacks were capped and not used.