So I am trying to replace the switch on my bathroom light which quit working months ago. I have no idea if the switch is actually the problem, but it's a cheap place to start. I've opened up the receptacle and found wires I was not expecting. Also, even with the breaker off, the wire to the switch I wish to replace is still testing postive for voltage. I have located the main line, the line to the light, and the line to the fan. But there's a fourth set of wires, and I don't where they go or what they do.

Here are some pictures, if it helps.



I really cannot afford to have someone come in, and I've survived without the light for months already. But it would be nice to have my nice, bright lights back in my bathroom. Any advice from someone who actually knows how to do this stuff would be greatly appreciated.

 

If it is a non contact tester that means nothing. The only wires you need to concern yourself with are the two on the switch. Turn off the breaker. Using a multimeter (preferably analog) or test light measure each wire on the switch to ground. if both show no voltage remove from the switch and connect together with a wire nut. If the light turns on you turn the breaker back on it is a bad switch.

 

Does the other switch on the right work? If it does, it is fed from the same hot so again, it would be likely your switch is bad. Follow Posternine's advice to confirm.