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Thread: weird wiring and wierd voltages on 3 dual switches...

  1. #1
    DIY Junior Member meweber1000's Avatar
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    Default weird wiring and wierd voltages on 3 dual switches...

    In our 1969 home that we've had 7 years, we have a mystery. There are 3 dual switches in one switch box by our back door (so 6 switches total), and until recently, we could not find anything that they control. We just found that ONE of the switches controls some outdoor light boxes from which the lights had been removed. In searching for the circuit breaker to this switch and these lights, we found that TWO circuit breakers power it. I opened up the switch box and found that each dual switch has two circuits feeding it (a separate line to each of the two switches), but the jumper between the two switches was never removed.

    I believe this is very wrong, because it seems that the load would have to exceed 20 Amp + 20 Amp before the breaker would pop, but all the wiring is only rated for 20 Amps. Or is there a reasonable explanation for what can be going on here, such that this is actually correct? SHOULD I GO AHEAD AND REMOVE THE JUMPERS??

    I detached the line wires from the switches to sort out exactly which breakers are feeding which switches, and I'm getting really weird voltage readings in one aspect. The top switch of two of the dual switches is fed by the same breaker, and they seem normal...the voltage across the line wires to their load wires is 120V as expected. The weird part is that for the bottom switches that are fed by another breaker, the voltages across those line wires to their load wires on the switches, are zero and 35V (on a digital meter...may be an artifact), but oddly the voltages across the line wires to the load wire from the OTHER switch is 120V. For the third dual switch, the voltage across the line and load wires is 120V for both the top and bottom, so something is definitely weird in the other two switches.

    More info: There are no neutral wires in the switch box...just a line wire and a load wire for each switch. Also, I don't know if it matters, but in all three cases, the bottom switch is fed by a breaker that is on the same side of the breaker box as the top and it is two breakers below (i.e., #10 feeds the top and #14 feeds the bottom, where #12 is between them). There's no way to tie the two breakers together.

    Switch 1 Top: fed by #8, 120V across line and load wires
    Switch 1 Bottom: fed by #12, 120V
    Switch 2 Top: fed by #10, 120V
    Switch 2 Bottom: fed by #14, 0V across line and load wires, but 120V across load wire of Top
    Switch 3 Top: fed by #10, 120V (connected to outdoor lights)
    Switch 3 Bottom: fed by #14, 35V across line and load wires, but 120V across load wire of Top

    Is there any rational explanation for these voltages and why these switches would be wired this way? Or was it just someone incompetent? Help!

    Thanks a million for any insight you have!!

  2. #2
    Plumber jimbo's Avatar
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    With all due respect , you are over your head. The voltage measurements always have meaning, but in your context, you have no neutral, so that limits what you can measure. Measurements across an open switch are meaningful in context, as is the 35 volt reading. You really need to have an electrician check this out. Everything MAY be perfectly normal.

  3. #3
    DIY Junior Member meweber1000's Avatar
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    Thank you very much. Let me ask you...so does it ever make sense to feed a dual switch for lights with two circuits and not remove the jumper?

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    DIY Senior Member kreemoweet's Avatar
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    It probably all made perfect sense to the fellah that installed it. It's certainly not proper. Your measurements with only a digital voltmeter
    are not very convincing: floating wires can measure anywhere from 0 to 120 volts, so measuring that means nothing. You should disconnect
    everything in that box and find out unambiguously where the other end of each wire is. Or call an electrician.

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    Plumber jimbo's Avatar
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    Are you CERTAIN that both black wires are hot feeds? One could be for devices "down the line"

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    DIY Junior Member meweber1000's Avatar
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    Yes, I'm certain. Disconnecting the wires from one pair of switches shows that the bottom switch had one hot feed, the top switch had another hot feed. With the jumper in place, this meant both switches were getting power from both, and this is why BOTH breakers must be off for the lights to not come on.

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    DIY Junior Member meweber1000's Avatar
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    Quote Originally Posted by kreemoweet View Post
    It probably all made perfect sense to the fellah that installed it. It's certainly not proper. Your measurements with only a digital voltmeter
    are not very convincing: floating wires can measure anywhere from 0 to 120 volts, so measuring that means nothing. You should disconnect
    everything in that box and find out unambiguously where the other end of each wire is. Or call an electrician.
    I cannot find what's on the other end. It will be very expensive for an electrician to do it. I'm not certain it's worth the expense, give it's been like this for many years and most of the switches have nothing connected to them. I may just cap off the extra wires in the box, and just make sure I have only one circuit feeding my new found lights.

  8. #8
    DIY Senior Member Chad Schloss's Avatar
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    obviously both those breakers are on the same feed or else the breakers would blow or the switch pass through would have melted long ago. who knows what you have there and why. If they do nothing, pull the wires from the breakers and cap them off there too.

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    IBEW Electrician big2bird's Avatar
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    Quote Originally Posted by meweber1000 View Post
    Thank you very much. Let me ask you...so does it ever make sense to feed a dual switch for lights with two circuits and not remove the jumper?
    No, because that would be a dead short, unless both feeds are the same phase, which leads me to believe there is a whole lotta assuming/confusion/misinformation here. I agree you need a real sparkey. If you wish to post a ppicture, I might be able to help more, but I may not at all. Long distance electrical work is "iffy" at best.

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    Electrician ActionDave's Avatar
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    I agree with the others. There is too much going on to diagnose without being on site.

  11. #11
    Electrical Contractor/Instructor jwelectric's Avatar
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    A #8 connected to a switch????????????????????????????????

    Never been able to get a #8 around the screw so this is enough to tell me one of two things, either you are totally lost and need to stop what you are doing or someone was able to do the impossible.

    No matter what the expense is call someone with knowledge before you end homeless.

  12. #12
    IBEW Electrician big2bird's Avatar
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    Quote Originally Posted by jwelectric View Post
    A #8 connected to a switch????????????????????????????????

    Never been able to get a #8 around the screw so this is enough to tell me one of two things, either you are totally lost and need to stop what you are doing or someone was able to do the impossible.

    No matter what the expense is call someone with knowledge before you end homeless.
    I "think" he is talking circuit numbers. I am not really sure though.
    It makes sense with the voltages he is reading, and why it is not tripping.

  13. #13
    DIY Junior Member meweber1000's Avatar
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    Quote Originally Posted by big2bird View Post
    No, because that would be a dead short, unless both feeds are the same phase, which leads me to believe there is a whole lotta assuming/confusion/misinformation here. I agree you need a real sparkey. If you wish to post a ppicture, I might be able to help more, but I may not at all. Long distance electrical work is "iffy" at best.
    Thank you! I will work on getting a picture, but you may have touched on something. The top and bottom switch in each of the three are DEFINITELY simultaneously powered by two different circuit breakers and they are not shorted, so by what you've said, they must be the same phase. I read that in a CB panel, CBs on the same side and every other one will be of the same phase...and that is exactly how they are connected.

    At risk of asking a really dumb question, is it possible that they did this to make three 40-amp-rated circuits of three different phases to drive say a motor or something? It's an interesting coincidence that there are 3 of these dual switches each being powered by two circuit breakers of the same phase, and I'm not a believer in coincidences.

    This is a very bizarre house (it's a circle!) and the original owner was crazy about security. There are remnants of three very extensive security systems around the property, including a couple of large video cameras and there are dead motion sensors all over the property. Perhaps this was done to drive motorized cameras? If that seems reasonable, I'll do what I can to reach those cameras and see if this is what powers them (our attic is so tight that it is almost impossible to crawl around in...I've had electricians refuse to do it in the past.)

    I will not do anything without getting an electrician, but this situation is so bizarre that if I can do some investigation and perhaps find what this went to, I can focus the effort and we can get to the bottom of it. Otherwise I fear I will spend over $1000 and he won't be able to figure out what it's doing any and we'll just disconnect it all and we'll never know. Or I could just leave it the way it has been for decades.

  14. #14
    DIY Junior Member meweber1000's Avatar
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    Quote Originally Posted by big2bird View Post
    I "think" he is talking circuit numbers. I am not really sure though.
    It makes sense with the voltages he is reading, and why it is not tripping.
    Yes, I'm talking about circuit breaker numbers. I'm sorry I'm not using the right language to describe this. I put all that information in, because in googling this, I found something that said where the CBs were located in the panel tells you what phase they are.

  15. #15
    DIY Junior Member meweber1000's Avatar
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    Quote Originally Posted by jwelectric View Post
    A #8 connected to a switch????????????????????????????????

    Never been able to get a #8 around the screw so this is enough to tell me one of two things, either you are totally lost and need to stop what you are doing or someone was able to do the impossible.

    No matter what the expense is call someone with knowledge before you end homeless.

    I don't think I'm totally lost, but I'm clearly not an expert and I don't even know exactly what the standard language is. I meant CB #8 and CB #10 power the one dual switch, and CB #12 and CB #14 power the other two dual switches. You all are providing me great clues and insight as to what might be happening here, and I really appreciate it.

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