Hot neutral reversed in old apartment

Discussion in 'General Electronics Chat' started by axxel, Aug 9, 2014.

  1. axxel

    Thread Starter New Member

    Aug 9, 2014
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    Just bought an old NYC apartment built in the 60's. I believe it was updated in the 80's, but not really sure.

    My surge protector indicated building fault wiring,and hot neutral reversed in all outlets except the kitchen and the window ac units, so I started doing a little investigating.

    First, I wanted to verify I have a good ground to earth. I did not see any ground wires in my outlets, and suspect the outlet box is grounded itself. I ran a jumper from the circuit breaker box chassis to all of my outlet grounds and they all showed continuity. I think the grounds are all ok.

    The first outlet that I wanted to inspect, that was indicating hot neutral reversed, I went ahead and pulled it out. To my surprise, the wiring colors look correct. The black is going to the narrow slot, and white wire to the wide slot. The odd part is that the kitchen outlet that tested good, also had the correct wire color polarity.

    I then wanted to determine the polarity of my faulty outlet. I plugged an extension cord into the known good kitchen outlet, ran it and set it on the floor next to my reverse polarity outlet. I put my multimeter probe into the extension cord wide slot, and the other multimeter probe into the narrow slot on the faulty outlet, and I see no voltage. I remove the lead from the narrow slot and insert into the wide, and I see 124V. Thus, probing from wide to wide slot shows a voltage. To me, this confirms that the outlet has reversed polarity.

    However, I am still confused as to why. Recall that all the wiring colors at every outlet were color coded properly (black going to narrow slot), but only a couple outlets had correct polarity voltage. Would this mean it was wired wrong at the circuit breaker box for most of the outlets and the others were done correctly? I have no way to tell, as I only have access to the circuit breaker switches, and cannot see any wiring, and am not going to attempt to pull the box out. It looks like it has not been disrupted in along time, and I am not going to do it myself.

    Just looking for some input here. Wondering if I should just swap the wires that show hot neutral reverse, or have an electrician come out and look. It seems easy enough, but I am not sure if I could have more issues than I realize.

    Thanks
     
  2. inwo

    Well-Known Member

    Nov 7, 2013
    2,433
    315
    If you can find the outlet that's wired wrong and correct it, it will fix them all.

    I wouldn't change the ones that are correct.

    Find the problem one.;)
     
  3. Nykolas

    Member

    Aug 27, 2013
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  4. axxel

    Thread Starter New Member

    Aug 9, 2014
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    Interesting. I didn't think about that.

    Any strategy to track that sucker down?

    Basically, just pulling all of them that indicate reversed polarity, and find the one with INCORRECT color coding?

    What about the fact that these are on different circuits. I would need to find the incorrect outlet on each one?

    Thanks
     
  5. axxel

    Thread Starter New Member

    Aug 9, 2014
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    I have one of those. It helped somewhat, but it isn't a sure thing to determine correct polarity and a true ground. I've seen videos where false grounds can trick even the most expensive circuit testers.
     
  6. crutschow

    Expert

    Mar 14, 2008
    13,003
    3,232
    It's, of course, possible that the wire is incorrectly connected at the breaker box, thus appearing to be wired correctly at the outlets.

    In general, I don't know that interchanging hot and neutral is a significant problem. Most new two prong devices are double-insulated and do not have the two-prongs polarized (one blade wider then the other) so it becomes unimportant which is hot and which is mutual. The only appliances to be concerned about are those with a two-prong polarized plug and you can probably judge whether the design of the product would allow voltage to appear on any surface metal if there were an internal short.
     
  7. axxel

    Thread Starter New Member

    Aug 9, 2014
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    It looks that way. So far, every outlet I've checked has proper color orientation.

    I've read that tv's and computers may be sensitive to hot neutral reversed....
     
  8. crutschow

    Expert

    Mar 14, 2008
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    3,232
    If they have a polarized plug, that could be true, perhaps related to their RF sensitivity.
     
  9. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    3,783
    944
    It is doubtful any of your appliances will experience any problems, but it should be corrected none-the-less.

    As a young boy long long long time ago. :)

    I stretched out my arm and balanced on one leg in an attempt to close the refrigerator door. I was standing in front of the stove where I was warming up some chicken noodle soup. My leaning position required my body to come in contact with the stove. Of course since I was home alone, I was clad in only the minimum required clothing, wearing my tighty-whities.

    The moment I made contact with the refrigerator door panel I received a nasty shock. The outlet into which the stove was plugged was reversed wired. It was a gas stove, but had a fancy, new at the time, electric sparking ignition feature. The installers had simply tapped into a junction box in the attic and wired it up. They were NOT true electricians, and for a long time no-one had discovered the problem because of the large distance between the stove and other appliances. The problem may never occur in your case depending on the electrical isolation conditions of your various appliances, but...

    Now that you know about your problem, you should get it corrected if you can.
     
  10. bladerunner

    Member

    Apr 15, 2012
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