I have power to a light fixture that then goes on to a switch... I would like to grab power from the cable going to the light fixture and run it to a receptacle (in another room). The cable is in my unfinished attic so its very convienent to create a junction... but I am curious if that would essentially create a circuit that would keep my light on or conversely, turning the light on would create a problem.

So are you saying you can read a hot wire at the light even with the switch in the off position?

I have not tested yet... just got to poundering the connection when I was on a plane... but I think your question suggest that there is no/should not be any power unless the switch is on... duh that makes sense... sorry for the inane question...

If what you are saying is correct, that you have unswitched power power going to the ceiling fixture. You can do what you propose.

If what you are saying is correct you will have only two wires in the switch box, black and white, and both will be connected to the switch.

Thanks.