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Discussion Starter · #1 ·
We have a 15 year old house, new to us. We have 4 light switches in one box that we are replacing. Two of them are 3-way switches, which work fine after replacing. The other two are both single switches (one is a dimmer) and after replacing them, they do not work. We tested and can see that when the breaker is on, there is no power coming to the wires for those two switches (they are next to each other).

They were originally wired such that one of the black wires went to both of the switches, so we duplicated that when we replaced them.

We are trying to figure out what could have happened that would make them suddenly not even get any power to the wires on that side of the box. There don't seem to be any loose connections anywhere, although there are a mess of wires in the box. We have a voltmeter so are planning to test the actual breaker. Beyond that, what can we do?
 

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How are you testing for voltage at the switches? Are there ground wires in there? Are you using a white neutral for the test?
 

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Discussion Starter · #3 ·
How are you testing for voltage at the switches? Are there ground wires in there? Are you using a white neutral for the test?
We have a voltmeter, with one lead against the ground and one against the black wires connected to the switch itself - both black wires had nothing. We just tried the white wires, and they have nothing. They are all just bundled together back there, which I assume is right because we didn't do anything to them.

I also just tested with a little non-contact voltage tester that looks like a pen, and the two switches that work have power to the black wires, the white wires have nothing, and the two non-working switches have nothing. I guess we might try replacing the switch, but that wouldn't explain why there's no power in the actual black wire going to the switch....
 

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Discussion Starter · #4 ·
We just took off both non-working light switches to test the wires with nothing attached. With the voltmeter, one lead on the ground and one on the black wires, they each get .17 or so. Not even zeroing out. The two working switches get 120 on each black wire when the switch is on, and zero out when it's off. Ground to ground zeros out. I'm not sure what else we can test.
 

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Are these switches on the same circuit?
If not, then try to reset the breaker and try again.
 

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Newbie Bill
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Remember that I too am a noob with little to no electical experience. So just thinking out loud.

Can you see where that ineffective black wire is coming from? Is it coming from a marette where other black wires are attached together or a direct feed from the wall?

Are there any other switches/outlets in the general area that you recently changed out, or are no longer working?
 

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Is anyway you can post the photo what it look like ?? somecase it may help us a bit when we try to find this troubleshooting on this one.

Merci,
Marc
 

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Discussion Starter · #9 ·
I think we figured out what is going on. We should have taken a picture before we removed the existing switches, because the wiring was funky and we missed a piece when putting it back together.

It turns out that one of the working switches was powering 2 of the other switches. They had hijacked the hot wire from the first working switch and brought it over to power the last two switches as well. I think the builders did it, because we could see where there used to be a red wire coming out of the bundle for the last switch, and they cut it - we think that was the hot wire and they screwed up, so they had to steal power from the working switch.

So we did the same thing, and they are all working now.
 
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