All the sudden "110v reverse negative polarity"

Discussion in 'The Garage' started by Ricardo Kuhn, Mar 20, 2013.

  1. Ricardo Kuhn

    Ricardo Kuhn a.k.a. Mr Rico Suave

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    Can this happen all the sudden...!?

    So we live on the same house for the last 3.8 years and last night when connecting the cable box coaxial cables I saw sparks, Yes sparks and the box was not even plug to the wall in at the time..

    In any case the cable man came today and he tells me we have "reverse negative polarity" in some of the outlets and we need to get them fix before they can replace the fried cable boxes (yes two of them fried at the same time, I guess by been connected to the same coaxial cable)

    Is this easy to fix by a clueless guy like me or do we need a call a expert.:huh

    Also, how can this polarity change can happen all the sudden...?
    we use the same outlets to connect the same appliances for years with out any trouble.

    Thanks in advance for the guidance and sorry if is a stupid question, since for me is not..:deal
    #1
  2. D.T.

    D.T. Difficult but useful

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    Check for hot & neutral wires hooked up wrong at receptacles.
    #2
  3. _cy_

    _cy_ Long timer

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    Gardner Bender GFI-501A Ground Fault Receptacle Tester and Circuit Analyzer

    <table class="product"><tbody><tr><td class="priceBlockLabel">List Price:</td> <td>$11.45</td> </tr> <tr id="actualPriceRow"> <td id="actualPriceLabel" class="priceBlockLabelPrice">Price:</td> <td id="actualPriceContent">$8.99</td></tr></tbody></table>

    [​IMG]
    #3
  4. Ricardo Kuhn

    Ricardo Kuhn a.k.a. Mr Rico Suave

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    But how can this be reverse with out changing anything, or was it wrong since we got the house and we never notice..??
    #4
  5. rapidoxidationman

    rapidoxidationman Easily trainable

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    If the 3 prong device shown by _cy_ shows any issues, then I'd start by taking the cover off the circuit breaker box and looking for anything obvious. If you're not comfy doing that then hire an electrician...
    #5
  6. spafxer

    spafxer Long timer

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    If I understand your correctly, it sounds as if your house ground system (possibly including the water pipes) has become energized. The coax is tied into the ground system of the house.

    This is very possible if the common conductor that goes back to your electrical supplier has become compromised, AND your house panel ground conductor is poor or non existent (depends on house age etc.)

    If this is the case, the electric supplier should come and take care of their side of the meter ON AN EMERGENCY BASIS.

    It's easy to put a volt meter on the cold water pipe outside and measure to wet earth or wet concrete. If you show AC voltage, YOU'VE GOT A DANGEROUS SITUATION.
    #6
  7. D.T.

    D.T. Difficult but useful

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    Reverse polarity is something that is real, but not "reverse negative polarity" :huh

    If there is voltage to ground somewhere usually it trips a circuit breaker in the panel. But if the amps are low enough or the CB is bad you have a dangerous situation as mentioned above. Usually fire. GFCI's will trip and you will get shocks too.

    How old is the house? Most appliances will work fine if the hot and neutral are switched around.
    #7
  8. Fuzzy Wrench

    Fuzzy Wrench Pick Your Tool

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    call an electrician, fix it right....not sure how it happened but some appliances don't care and run anyway 'cause AC is just that, alternating (back and forth)...could be a problem with the neutral wire...
    #8
  9. Ricardo Kuhn

    Ricardo Kuhn a.k.a. Mr Rico Suave

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    we are a little scare so we call a expert, hopefully will know more by tomorrow..
    1926 or something like it with knob and tube in at least some parts of the house even if the panel is newer.
    [​IMG]
    #9
  10. caryder

    caryder Been here awhile

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    There is no "polarity" on an AC circuit. Just Hot (power) and Neutral (reference). The "polarity" reverses at the frequency of the generator (usually 60 Hz (times/second) in the US or 50 Hz in Europe).

    To answer your question, if the wiring of your outlets are reversed, they were that way to start with. What fried your cable boxes was a voltage surge either on the power supply or the cable itself. This is why it's a good idea to have your electronics connected to a surge suppressor although some cable companies don't like that if the cable signal is weak because they don't know what the suppressor is doing to the signal.

    It's easy to use one of the circuit testers recommended by the above responses to check the wiring of each outlet in your house. The testers are cheap and some power companies offer to lend them for free. Once you figure out which outlets are suspect it's generally easy to refer to any handyman website and learn the white wire goes to the wide prong (usually the silver screw) and the black wire goes to the narrow prong (usually the brass colored screw). Green wire is ground and goes to the base (usually tinted green) prong at the bottom of the outlet. Make you turn off the circuit breaker or pull the fuse before you work on the outlet. You can use the circuit tester to verify the power is off. Otherwise call an electrician to fix the suspect outlets.


    Chuck
    #10
  11. P B G

    P B G Long timer

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    #11
  12. the_gr8t_waldo

    the_gr8t_waldo Long timer

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    reverse negative polarity- sounds like double talk! but it might make some sense to a cable guy. reguardless, if you haven't had anything done to the system, then it has to be at the transformer, out on the pole. and if it is, then the power company owns that problem!. (had a lighting storm in the last few days?) call 'em up and get them to figure out if they are delivering the right product to your home. before assuming that it's in your home
    #12
  13. foxtrapper

    foxtrapper Been here awhile

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    Agree, the wires in your house didn't just reverse themselves. And being reversed wouldn't cause sparking. What you've described sounds like what spaxfxer describes, which is *darn* dangerous. It is not something I'd recommend dinking around with on a leasurely basis.

    If I had an outlet that blew sparks at me when I plugged something in, and especially if it didn't blow the breaker when throwing those sparks, I'd be quickly investigating and either fixing it, or having it fixed, pronto. I do not like electrocution in the shower, nor do I like having my house burn.
    #13
  14. ph0rk

    ph0rk Doesn't Care

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    I wouldn't screw around with this - sometimes it is well worth paying a professional, though if the house has wiring that old you may end up really paying.
    #14
  15. H96669

    H96669 A proud pragmatist.

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    Get yourself ready if you call the power company. They may not fool around and just remove the meter.:eek1Different problem I had but call the electrician and get it fixed they told me and just then we will come back and reconnect. That was 2-3 days without power.:eek1

    I am always ready for such days.....water, food, heat and cooking.:wink:
    #15
  16. ragtoplvr

    ragtoplvr Long timer

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    The other problem you have is Knob and tube homes I have seen never have ground wires.

    Rewiring is is quite expensive, copper is high now, and the labor is not cheap.

    first step is to get the tester, and then you can determine how to fix the incorrectly polarized outlets.

    Getting a proper ground on the house is much more difficult.

    Rod
    #16
  17. ttpete

    ttpete Rectum Non Bustibus

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    There are lots of homes that don't have grounded outlets. Anything built in the 1950s or before won't have them.

    What I think is happening here is that the cable coax shielding is always grounded at the entry point to the house. If an outlet is wired backward, you could see voltage between the supposedly neutral side of the outlet and that external ground connection, and that could have fried the cable box.

    Use one of the plug in testers, and if that indicates a reversed connection, check the outlet first. If that's wired OK, you'll have to go back to the breaker panel and check connections there at the breaker for that circuit. The breaker should have the black wire, and the white should go to the neutral bus.

    Seeing you have some knob and tube work, the neutral and hot could have been unknowingly transposed in some other place. If that's the case, the simplest fix would be to flip the wires in the outlets.
    #17
  18. kiwi_outdoors

    kiwi_outdoors Been here awhile

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    Street transformer is center tapped
    center = zero volts = white wire inside your house
    either and of the coil is about 115V relative to center - these go to 2 lugs on your breaker panel (black and black or black and red wires)

    so thats the three wires coming into the house

    the ground wiring inside the house is a "backup" path for current in case the appliance has a problem

    ordinarily grounding is for local safety, so we use an earth rod and ground metal pipes and so forth

    your sparking sounds interesting, and warrants a professional to check it out
    #18
  19. jdrocks

    jdrocks Gravel Runner

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    no professional electrician ever made up that subpanel, and i'm betting no building inspector ever put his eyes on it.

    time to call a licensed electrician, have him check the whole works.
    #19
  20. Ricardo Kuhn

    Ricardo Kuhn a.k.a. Mr Rico Suave

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    The electrical master just left, one wire was lose on the receptacle, but except for that everything was fine, well at least he did not find any other funky issues.

    Ps: pretty sure I will have my 220V welder wire up at last, the guy is great..
    #20