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Duncan25 06-25-2010 07:35 PM

Light wont work after changing switch
I was just replacing several switches (a three set ) and a plug in a bathroom this evening. The three switches were connected to two separate fuses. I made a basic mistake and one of the switches wasn't disconnected and I got a bit of a shock. I then switched it off at the fuse box, changed that switch and a few others and turned them all back on at the fuse box. Two of the swithces work fine but the light connected to the switch from which I got the shock won't work.
I've checked the fuse box and it all seems OK. The same fuse that connects the switch that won't work also connects several other lights in other rooms which are working fine.
Any ideas. I've check the power using and electricity meter on the switch and got a signal once but haven't got anything since. If the fuse isn't at fault, what else could be causing this problem

kbsparky 06-25-2010 07:40 PM

Bad bulb? Stranger things have happened ....

joed 06-25-2010 07:52 PM

Check for GFCI in another bathroom, garage, outside receptacle etc.

Duncan25 06-25-2010 08:52 PM

No luck yet
Thanks KB and Joed. Bulbs are good and I checked all the GFCIs and non are tripped. Any other thoughts. Could it be a bad ground wire causing the problem

oberkc 06-25-2010 09:53 PM

I would not expect a bad ground to affect power to the switch. Neither would I expect a bad neutral to affect power to the switch. This could, however, affect your ability to measure voltage (if you use a volt meter to measure voltage relative to a failed neutral, you may not get a reading). A bad ground should not cause your light to cease working, but a bad neutral would, even if you have power to the switch.

If you are confident that you do not have power at the switch, then the problem is between the switch and panel. This could include bad wire, bad connections, bad fuses, etc. If you measure a voltage at the fuse, then you have eliminate a bad fuse, and the problem must be "downstream".

Do you have an idea of the wiring of this circuit? Could the switch be getting power from the panel through other devices, such as outlets, other switches, etc.? Are any other devices on that circuit not working?

Duncan25 06-26-2010 11:32 AM

The fuse and every other outlet connected to it has power. If it is a problem with the neutral what can we do to fix it. Also, before I changed the switch the switch and light were working fine. What would have caused the neutral to fail.

Thank you

nap 06-26-2010 11:48 AM

How do you know bulbs are good? Did you replace them?

did you replace the switches with the correct type of switch (SPST for SPST)?

Do you have a voltage tester? If so, check from a ground or neutral to each terminal screw on the switches. Test with the switch in both positions. In one position, you should have power to only one screw and in the other, power at both terminal screws.

With the switch that is having problems, If you don't have any power at all to the switch, you made poor joints in the wire going to the switch. If you have power at only one screw regardless of the position of the switch, you have a bad switch. If you have power at both screws and still no light, you have either a bad lamp or some broken wire or bad connection from there to the fixture.

Duncan25 06-27-2010 07:35 AM

Thanks nap,

Iíve tried several bulbs so I donít think thatís the problem. I also think the switch is the correct type.
I took your advice with the voltage meter and have power to one of the screws in one position and none of the screws in the other position. Iíve tried three different switches though so Iím not sure the switch is the problem either.

Any other ideas?

nap 06-27-2010 11:02 AM


power to one of the screws in one position and none of the screws in the other position.
you are checking from a terminal screw to a known ground or neutral, yes?

I ask because if by chance you are checking from terminal screw to terminal screw, that is what you should get.

a SPST switch is almost always marked on and off. Which way are you getting what reading?

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