I read the post about a GB type detector with a transmitter and
receiver. But will it or something work with lower than 110 volts??

It's not 110v wires that I am confused by. I ran 4 pieces of
telephone line to my attic, one for the telephone**, one for a burglar
alarm sensor*** in the window frame, one for a smoke detector for the
burglar alarm, and one I don't even remember what for.

Now the phone jack doesn't work and I want to splice in a patch in the
attic instead of coming all the way from the basement again, but I
don't know which of the four. I didn't label them because I thought
they would never break. and there are a lot of empty boxes etc.
making it difficult to physcially trace the wires. I can probably
borrow the GB tool from a friend who installs burglar alarms. And I
think it would be fun to use. If I can use it??

**The previous owner had sheetrocked over the phone jack!

***I know now, I think, that I shouldn't have used phone line to
connect a sensor to a transistorized burglar alarm panel, but I had a
lot of it. I read here, I think, that there is some twist in 4-wire
phone line, but is it enough to keep currents induced by lightning
from burning out an alarm?? I was leaving the house one day when I
saw smoke coming from the keypad/control panel, and sure enough it
didn't work anymore. I don't remember any recent lightning at that
time, but did I make a big mistake by using phone line to connect to
remote sensors? Thanks.