"ng_reader" wrote in
:

I will go back and read my Basic Electric book again, but is it a
definite that if I get to a gang of switches, that I can run another
circuit off of ANYTHING in there?

Or, in other words, is it possible that I try every combination of
connecting white-white, white-black, black-white, white-black/white,
black-black/white, and so on and so forth that I NEVER get a good
connection to run my *new* switch from?

It's a gang box of 3 switches, one of which is a 3-way, the other
"normal".

Trying every combination would be a bad idea. You should study the
situation and understand the purpose of each wire. If you're not willing
to do this then call an electrician.

It is possible that you could never get a good connection to run your new
switch. You need 3 wires to be able to branch off an existing circuit to a
new location: hot, neutral and ground. You have hot and should have
ground. The question would be the neutral. You need to look for a bundle
of white wires in the box that has no connection to any of the switches.
If you have that then you should be OK. If all the incoming wires connect
to the switches then you can't extend from that box alone.

You also need to be careful about stuffing too many wires in a box. Look
for "box fill" in your book or the internet to learn about that.

Doug