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where is this mystery 35v coming from?

Discussion in 'The DIY corner' started by Jayne, Jan 13, 2020.

  1. Jayne

    Jayne Just here for the memes Charter Member Supporting Member

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    Removing ceiling fans from two rooms in an office and replacing them with LED ceiling lights. Easy.

    Each room has two wall switches, one makes the fan go, the other the lights. The wiring is white/black to the fan, white/red to the light, common green.

    Here is what I expected to get when testing:

    switch #1 ON, you get 120v to white/red
    switch #2 ON, you get 120v to white/black

    However, what I found with the meter was:

    switch #1 ON, you get 120v to white/red
    switch #2 ON, you get 120v to white/black AND 35v to white/red
    switch #1 and #2 ON, you get 120v to white/black and white/red
    switch #1 and #2 OFF, you get zeros everywhere


    So... where exactly is that rogue 35v coming from? Both rooms had the wiring the same and both had the 35v on the 'off' circuit when one was active and both the light and fan have been working for years AFAIK (wife is just moving into this office this week). Wiring looks original to the building (mid-90s) being covered in over-spray from the original white color the rooms were.

    I can see some sort of mis-wire giving us 120v on both, but 35v? The fans were not physically hooked up when I was testing, just the multimeter so I'm not even sure what would be stepping down the 120v to 35v. Both rooms were exactly the same, and that 35v was rock steady in both.

    I disabled switch #2 since it goes nowhere now and I didn't want 35v going to the new LED fixture if someone flipped that second switch. No idea what that would do to the light. But... for the last N years has it been that if someone had the fan running without the light the bulbs were getting 35v (yet not lighting up)?
     
    Last edited: Jan 13, 2020
  2. Catfish

    Catfish E Pluribus Mendacium Charter Member

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    Is there a dimmer anywhere in this setup?
     
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  3. Jayne

    Jayne Just here for the memes Charter Member Supporting Member

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    Nope. Just two standard on/off switches.

    The office is also empty so other than ceiling lights, the only thing plugged in anywhere is the cable modem / router box. Not even sure that's on the same circuit as the office lights.
     
  4. Carolinatlc

    Carolinatlc Member Charter Member Supporting Member

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    Did you check the black and red wires back to ground? What you are probably seeing is a small phantom voltage from the switch that is turned on. There probably is no real voltage there.
     
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  5. Mirac

    Mirac Epic Replies ---> Charter Member Supporting Member

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    touch the neutral to ground... does the GFCI Breaker trip in the panel ?
     
  6. rdinatal

    rdinatal Better late then never...

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    Oh, this is getting interesting... ;)
     
    Last edited: Jan 13, 2020
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  7. Jayne

    Jayne Just here for the memes Charter Member Supporting Member

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    I did not. I was afraid to start poking around randomly at that point.

    It's officially fixed like this, it's pretty clean for DIY. :)

    upload_2020-1-13_15-31-45.png
     
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  8. Jayne

    Jayne Just here for the memes Charter Member Supporting Member

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    Looking for random voltage on the ground, or are you trying to kill me?
     
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  9. BlackGun

    BlackGun Well-Known Member Supporting Member

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    I would have to see it.

    1. Sounds like one of the wires is a traveler wire from another switch location.
    2. “Green is common.” OP. Not sure what you mean but it’s the grounding wire to fans, lights, and possible metal box.
     
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  10. Johnny

    Johnny Misanthropist Supporting Member

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    Points reduction, your faceplate screws are not aligned.
     
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  11. noway2

    noway2 Senior Member Charter Life Member

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    My guess would be that it's an induced voltage caused by mutual induction and / or parasitic capacitance from the non energized wire that is open circuited being run in parallel with the 120Vac energized wire.

    Do you have a resistor you could put on the red wire to ground and then measure the voltage. If it is induced voltage, if you give it a discharge path the voltage should collapse.

    I've ran into this on control wire run along with power wires. It can induce enough voltage and current to turn on an opto-isolator and make you think the circuit was active. Placing a load resistance across it fixed this.
     
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  12. Tim

    Tim I am....an enchanter. Staff Member Benefactor Charter Life Member

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    Well, I finally replaced my faulty GFCI yesterday, so I'm pretty much an expert electrician at this point.

    I'd say you have something wrong and it needs to be fixed. $150, please.
     
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  13. skiles

    skiles Reloaded Charter Member Supporting Member

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    I understood "red wire". :eek:
     
  14. Scsmith42

    Scsmith42 Member Benefactor Charter Life Member

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    Kelly, are any of your switches the type that light up when they are off? If so the 35V may be part of the switch light.
     
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  15. Brian K

    Brian K Resident Douchenozzle Charter Member Supporting Member

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    Curious what amperage is coming across at 35v. When you stick the white/red wires on your tongue does it tingle?
     
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  16. noway2

    noway2 Senior Member Charter Life Member

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  17. skiles

    skiles Reloaded Charter Member Supporting Member

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    Last edited: Jan 13, 2020
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  18. random

    random Active Member

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    Black & Red are hot, white is neutral (prob. what you mean by "common"?), green (or bare) is ground.

    I would be really interested in seeing the wiring of the switches. That sounds like something is partially crossed, but it's weird that it's only in one direction.
     
  19. Carolinatlc

    Carolinatlc Member Charter Member Supporting Member

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    What I said but with more accurate terminology. Induced voltage was what I was looking for. I’ve seen almost the exact thing before. Wires run in the same path with wires with power can pick up induced voltage occasionally. I’m mechanical but work around plenty of electrical guys.
     
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  20. BlackGun

    BlackGun Well-Known Member Supporting Member

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    I had a blank cover in the living room for many years and this past year I put a fan/light combo in. I had 50 volts on a wire to the new fan/light combo when one of the switches was off. I had 5 switches total in two spots, 3 in one box, and two in another. The traveler wires were not correct and not marked. It took over 2 hours to determine the issue.
    If you can’t use a meter to ohm out the wires you need an electrician on location. My situation also involved general lighting circuits commonly called receptacles fed from same circuit.
     
  21. Jayne

    Jayne Just here for the memes Charter Member Supporting Member

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    One left somewhat crooked for the OCD crowd.

    IMG_6674.JPG
     
    Last edited: Jan 13, 2020
  22. Jayne

    Jayne Just here for the memes Charter Member Supporting Member

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    Nope, all just low budget on/off.
     
  23. Jayne

    Jayne Just here for the memes Charter Member Supporting Member

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  24. Jake

    Jake Happy to be here

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    This is likely what is happening. High impedance digital multimeters often show this sort of thin. Can you find an old analog meter? If it is just the induced voltage Noway2 describes, it should read zero on any analog meter without a power switch. (If it has a power switch, it may be an FET input meter that could have the same problem.)
     
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  25. Schattenreiter

    Schattenreiter Member

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    And the paint is a little scuffed on the lower right one. Just saying. ;)
     
  26. Jayne

    Jayne Just here for the memes Charter Member Supporting Member

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    I don't, but I've received another (off forum) confirmation that this is what I'm seeing. The tests are as everyone is describing, but since it's all back an 'in production' now I'm just going to leave it.
     
  27. Jayne

    Jayne Just here for the memes Charter Member Supporting Member

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    Thanks to all who replied, we can put this thread to bed now (unless more mockery of the switch plate and/or the fact that the switch color doesn't match the plate cover is required). I hate those 'ivory' colored switches and outlets but it's not my office so I won't have to look at that and the wife didn't notice.
     
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  28. rdinatal

    rdinatal Better late then never...

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    @Jayne

    I want to know where you acquired the toggle cover! Man, I could use a couple.
     
    Last edited: Jan 14, 2020 at 11:41 AM
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  29. fieldgrade

    fieldgrade Well-Known Member Benefactor Charter Life Member

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    28 posts in and this thread is worthless until somebody gets shocked with at least 220v
    [​IMG]
     
    Last edited: Jan 14, 2020 at 10:30 AM
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  30. Inglis

    Inglis Member

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    If you get by 220 or more you get a Very bad copper mouth and you might even piss in your shorts. It is not fun.

    the 35 volts may be from a loose ground wire in your electrical system.
     
    Last edited: Jan 14, 2020 at 12:41 PM
  31. fieldgrade

    fieldgrade Well-Known Member Benefactor Charter Life Member

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    Some old timers here know I’ve sharked myself with 220 not once, but twice.
    Posted about it.
    Good times.
     
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  32. Scsmith42

    Scsmith42 Member Benefactor Charter Life Member

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    Got zapped by 240 while standing on the top of a 12' ladder. Not sure what hurt worse - the shock or the impact with the ground...
     
  33. Johnny

    Johnny Misanthropist Supporting Member

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    Is that when you get shocked and shart yourself?
     
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  34. fieldgrade

    fieldgrade Well-Known Member Benefactor Charter Life Member

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    Maybe.
    :D
     
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  35. Brian K

    Brian K Resident Douchenozzle Charter Member Supporting Member

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    No kidding. That'd keep the kids from leaving the lights on.
     
  36. pee wee

    pee wee (jloverman3) Charter Member Supporting Member

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    575v is a beotch. Split my thumb open and arm hurt for 2 days afterwards.
     
  37. rdinatal

    rdinatal Better late then never...

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    My kids are out and paying their own electric bills. This is for my wife to not turn certain ones on that she never turns off!
     
  38. Brian K

    Brian K Resident Douchenozzle Charter Member Supporting Member

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    14 and 17 at home with the same issue. At night every single light needs to be turned on to light their path to the kitchen, then left on.
     
  39. LeeMajors

    LeeMajors Bionic Man Staff Member Charter Member Life Member

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    I got 2 from Amazon about a year ago
     
  40. Jayne

    Jayne Just here for the memes Charter Member Supporting Member

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    Had the wife pick them up at Ace Hardware on her way to the office. I just sent her a screen shot and they appeared 30 minutes later. Like amazon right-the-hell-now delivery.