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grgryl 08-07-2008 11:20 PM

Problem changing light switch
 
I changed a few light switches with no problem as both wires connected to the switch were black. THen I came across a switch, with a black and white wire connected to the switch. After I changed out the switch, I turned the breaker back on and it immediately shut off.

I was later able to turn the breaker back on and the other switches/lights in that circuit work but that switch (with the black and white connected to it) doesn't work. I tried switching the polarity and still doesn't work.

I checked the light bulb and it is not broken. Why doesn't the switch work? It's not a 3 way switch since there is only one switch that controls the light.

Stubbie 08-08-2008 12:19 AM

1 Attachment(s)
What you have is a switch loop. the power is at the light fixture and just a black and white and ground ran to the switch. The white is connected to power (black) at the light fixture box and brings power to the switch. The black that was connected to the switch is your switched power for the light. It looks like this....below.
Most likely you changed something in the wiring. so can you tell us how you connected the black and white wires that were on the original switch?

grgryl 08-08-2008 12:50 AM

I tried my best not to change the wiring. I believe my switch is what your diagram indicates. A black and white wire is connected to the switch, but the switch itself doesn't have different colored screws. I think the black was on top and white was on the bottom and of course the ground was connected to the switch. When I replaced the switch I tried to keep the black on top and white on the bottom. When installing a switch, does polarity make any difference ? (since the switch have same colored screws).
Am I supposed to use a different type of switch for this kind of connection?

grgryl 08-08-2008 01:02 AM

possible problem
 
With all my switches, I've been wrapping the wire around the screws because the wire is too thick and doesn't fit in the hole (quick connect). But for the switch with the black and white wires, would that create a short circuit?
Or am I supposed to use a double pole switch instead of single pole?


Quote:

Originally Posted by Stubbie (Post 146897)
What you have is a switch loop. the power is at the light fixture and just a black and white and ground ran to the switch. The white is connected to power (black) at the light fixture box and brings power to the switch. The black that was connected to the switch is your switched power for the light. It looks like this....below.
Most likely you changed something in the wiring. so can you tell us how you connected the black and white wires that were on the original switch?


petey_c 08-08-2008 06:31 AM

Stubbie's right, you have a switch loop. Which screws (except the ground screw) of a single pole switch shouldn't really matter. (I always like to make the black the hot coming down and mark the white with tape so someone doesn't think it's a neutral.) It sounds like something might have shorted out, causing the breaker to trip immediately. Perhaps a nick in the insulation when you pushed the switch back into place. The wire may have broken allowing the breaker to be turned on. Turn off the breaker and recheck. pete

TazinCR 08-08-2008 07:11 AM

When you push the wires in you may have caused the ground to come in contact with the screws or the wire is nicked as petey stated. Pull it out and leave it hanging and see if it works.

grgryl 08-08-2008 08:33 PM

switch probably faulty
 
Thanks for all the suggestions; I tried them but still had trouble. I then changed out the switch and it works now! I guess there was something wrong with the switch.

frenchelectrican 08-09-2008 03:54 AM

From time to time the switch do fail over the time and it do happend.

And that why I always carry few extra switches along with me when I get service call something like that.

Merci,Marc

TazinCR 08-09-2008 07:39 AM

A bad switch would not cause the breaker to trip. Time to fess up. You had a short correct?

grgryl 08-09-2008 12:57 PM

lol, maybe there was a short when the breaker tripped but the funny thing is when I turned the breaker back on, the switch wouldn't work. (I'm talking about a brand new switch). I took out the switch, put it back in, still doesn't work.

Then I finally put in another new switch and it works. I'm not hiding anything here! But I appreciate the suggestions. I changed all the switches in my house without any problems.

I have to say the only inconvenience is removing the old switches because they weren't wrapped around the screw but they were inserted in a hole (quickconnect) and I had to yank it out with pliers or cut it.

Yoyizit 08-09-2008 01:40 PM

Quote:

Originally Posted by TazinCR (Post 147205)
A bad switch would not cause the breaker to trip.

". . .put in another new switch and it works"

Did the switch have a ground terminal, so there is a connection inside the switch between the switch contacts and the switch ground?
If you still have the old switch, this can be checked.

grgryl 08-09-2008 01:49 PM

Yes it did. I always connected the ground terminal.

Quote:

Originally Posted by Yoyizit (Post 147282)
". . .put in another new switch and it works"

Did the switch have a ground terminal, so there is a connection inside the switch between the switch contacts and the switch ground?
If you still have the old switch, this can be checked.


fw2007 08-09-2008 01:50 PM

I think what happened, is that when the new switch was installed, there was a short on the switched side, and when you turned the breaker back on, the switch was in the on position, so power shoreed to ground through the switch.
The instantaneous high current caused by the short (which tripped the breaker) destroyed the switch internally, so it no longer connected power to the switched side, thus no more short, and no light either.

If you're using metal boxes, you've got to be careful when pushing the switch and wiring back into the box. It could be that the bare ground wire contacted the switch terminal.
For this reason, I always wrap tape around the switch, covering the terminals. I am also very careful about where to route the ground wire. Always running along box wall to the terminal on the switch or outlet.

FW

Yoyizit 08-10-2008 08:11 AM

Quote:

Originally Posted by fw2007 (Post 147285)
I think what happened, is that when the new switch was installed, there was a short on the switched side, and when you turned the breaker back on, the switch was in the on position, so power shoreed to ground through the switch.
The instantaneous high current caused by the short (which tripped the breaker) destroyed the switch internally, so it no longer connected power to the switched side, thus no more short, and no light either.

Yes.

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grgryl 08-10-2008 01:26 PM

Quote:

Originally Posted by fw2007 (Post 147285)
I think what happened, is that when the new switch was installed, there was a short on the switched side, and when you turned the breaker back on, the switch was in the on position, so power shoreed to ground through the switch.
The instantaneous high current caused by the short (which tripped the breaker) destroyed the switch internally, so it no longer connected power to the switched side, thus no more short, and no light either.

If you're using metal boxes, you've got to be careful when pushing the switch and wiring back into the box. It could be that the bare ground wire contacted the switch terminal.
For this reason, I always wrap tape around the switch, covering the terminals. I am also very careful about where to route the ground wire. Always running along box wall to the terminal on the switch or outlet.

FW

Yep, the switch was "on" when I turned on the breaker. And your explanation seems to be the cause!


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