Hi:
My porch light suddenly does not work at all. I have tested the switch, the bulb and the fixture seaparately and they all are good. I checked the switch with power on with my neon tester and both the live and neutral light up the tester. I disconnected the cable going to the fixture at the switch and inserted the fiture directly to the incoming cable and it works fine. Does that mean my house wiring is faulty? This is original wiring since the house was built over 20 years ago and has never been tamperered with? Can the cable become faulty although it is behind the walls?

Also if it is the cable that is faulty is it an expensive job to get it replaced since it would require tearing down the walls?

I would apprecaite any suggestions.

Unlikely to be the wiring. At 20 years the wiring is still in its adolescence. Replace the switch.

I did replace the switch but it gave the same symptoms i.e. no light and the live and neutral wires both showed voltages at the switch end and at the fixture. The only time the light works is when I completely bypass the original cable and connect a different cable to try.

So are you saying you think the switch leg is bad? The wiring from the switch to the light? One way you could test that theory is to completely disconnect and isolate it from the power source and other connections whether it comes hot from the switch (normally) or hot from the light to the switch. Twist the hot and neutral together at one end (either the switch or the light) and then go to the other end and test for continuity with a multimeter. Since they are tied together you should have continuity. If not, you know you have an open wire somewhere.

Let's start with the basic stuff here. First, a switch does not use Neutral. It for an hot wires only.

Doy you have a voltmeter? If not, get one.

Set the meter one step up from 120 VAC. With the switch OFF, set the black probe on the lower screw and the Red probe on the upper screw. What voltage do you see on the meter. Next flip the switch ON, now what voltage do you see on the meter?

At the lamp, with the switch on, put the black probe on the base knob (centered inside the bulb socket and the red probe on the threads for the bulb. What voltage do you see?

Please return here with the answers.

Thank you all for your help My light is working now. The problem was a loose connection at the junction box that connected two lights, one at the porch and the second above the garage door. Tightening the connections fixed the problem. Thanks again.