You've probably seen this question million times. I am installing a new ceiling fixture in my room where there is already an exisiting light switch. After inspecting the attic, I discovered that all access to the light switch is blocked off by plywood. I noitced though the wire going to the electrical outlet that is controlled by the switch was accessible. I figured that If I cut this wire then splice them together as well as the new wire to the light fixture, connecting white to white, black to black and green to green would do the trick. I did this the outlet works fine, but the light fixture stays on when the light switch is off. Is there a way I can rectify this without taking out my saw to get to the lightr switch?

Hooking black, white, and green to another Black, white and green will make that constant live as well.
In some instances Electricians, do a switch loop with 1 cable, White will be taped with black to identify it as a Hot, and the black will be the switchleg to light fixture.
You basically need to have power to 1 terminal of the switch and wire to the fixture goes to other switch terminal.

Thanks for the response. I'm not sure I follow. Is there any way to make the fixture go on and off (it's constantly on now) without having access to the switch. I can't run a wire to the switch as there is plywood nailed to the floor in the attic. If this isn't possible I also noticed that the other light switch, it is stacked, controls the attic lights, a series of outlets in the attic. Could I connect my wire to on of these outlets and control it from the switch below.


Love the Keys, man.

If you could provide a little drawing that shows the boxes and wires running to them, would be of great help.
http://www.do-it-yourself-help.com/wiring_switches.html

How many wires in the cable you spliced into?

Switched outlets can be wired two ways. Most often power is taken to the outlet then a switch leg is run to the switch. When wiring like that ther is no neutral at the switch. The white is used to take power to the switch and the black is used to take it back to the outlet when the switch is on. If you outlet is wired this way the light should not work at all. In this case the white is not a neutral. It is a hot.
The other way is to run power to the switch. Then run a switched and an unswitched leg to the outlet, along with a neutral. In this case you have three wires going from the switch to the outlet.

How many wires?

In my attic there was one 12-2 wire that came from the area above where my switch was in a little notch in the floor and going down to where my outlet was, through another notch. As I said the opening above my switch was blocked off with plywood (the flooring of my attic, I assumed that this was coming from my light switch to the outlet. I thought, wrongly that if I spiced into the 12-2 then my light fixture would behave like the outlet, shut off when the switch was off. I spiced into this wire, black to black, wite to white and ground to ground. The outlet works fine but the light stays on.

I think you got the wrong wire. Pull the switch and the outlet and tell us what wires are in each.