I have a problem and wished someone could help me out there. I did a new electrical wirring in the toilet and connected halogen laps to the ceiling. Everything was OK for about two months , until today when I cam home and found that I can't switch on the light. I taught maybe it was the switch but I opend it and tested it with a light tester and the wire seems to be neutral( both ends) I then removed all the three lamps I had connected and tested the wires at the switch again. And this time it was hot again. So anytime I connet the bulbs, the hot wire turns neutral. What went wrong please help.

You really shouln't be wiring in the commode. Water and electricity don't mix.:) A little humour first.

What is likely happening is you have a loose hot connection. Under load, your installed lamps, the circuit opens. Under an extremely light load, you light bulb tester, it works.

Your use of (neutral) is confusing too. Measuring requires a reference. I'm assuming you used a known ground or neutral. You should had just said, my test lamp doesn't light from either terminal of the switch to a known (ground/neutral).

This misunderstanding happens all the time.

Did you happen to install recessed light housings?

If you did, did you make sure that there is no insulation within 3" of any of the installed fixtures?

Addendum:

1) Switches do not use Neutral. They connect to the circuit via "Hot" conductors. Their purpose is to interrupt the flow of electricity to the appliance. If there is a white wire attached to the switch, it should be connected to the supply and feed the switch. It also needs to re-identified with either black electrical tape or a Black Sharpie to signify that this is a "Hot" conductor.

With a continuity tester, you can test if the switch is working by connecting one end of the tester to the lower screw, then touch the upper screw with the probe. With the switch in the "OFF" position, the lamp in the probe will not glow. With the switch in the "Closed" position, the lamp in the probe will light up, signaling that there is continuity between the screws.

Thanks men for your quick responses. The switch is working fine. After some careful examination of the divider box( sorry don't know how its called) realised there is no continuity in the hot wire to the Bathroom switch. So I believe the cable must be burnt somewhere in the wall. Ok but onething that stills confusses me is that WHY DID MY SCREW TESTER SHOWED ME THERE WIRE WAS HOT EVEN WHEN THERE WAS NO CONNECTION? Anywaw I have bought some new cables and been cutting my way on the wall to do a new installation. Once again thanks for your helps.