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    charlesnoyes's Avatar
    charlesnoyes Posts: 1, Reputation: 1
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    #1

    Dec 27, 2007, 09:38 PM
    Reversed polarity receptacles 15 amp
    My house has bx cable wiring with grounded receptacle boxes per a test meter indication. I want to replace two slot outlets with three hole grounded receptacles but the polarity on those in place is reversed with the long slot hot and the short slot neutral. What's the best course?

    Thank You!
    KISS's Avatar
    KISS Posts: 12,510, Reputation: 839
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    #2

    Dec 27, 2007, 09:58 PM
    White should go to the silver screw. It will connect to the wide blade and will be neutral in 2 and 3 prong outlets.

    Black should go to the brass screw. It will connect to the shorter width blade and will be hot in 2 and 3 prong outlets.

    The 3 prong outlet ground needs to be separately bonded to the box, You can buy green pigtails with an attached screw for this.

    It's easy to get confused depending on what world you were brought up in. I suspect that someone THOUGHT erroneously that black was (-) or neutral. Red, for instance, is negative in the thermocouple word, but in the automotive world it seems to be positive.

    I guess, you'll have to fix it and check with an inexpensive outlet tester when your done.
    donf's Avatar
    donf Posts: 5,679, Reputation: 582
    Printers & Electronics Expert
    		  
    #3

    Dec 28, 2007, 06:44 AM
    Charles,

    Can you give me the colors of the wires inside the BX cover. For the life of me, I can't imagine any self respecting electrician using "White" as a hot conductor. A previous home owner, maybe thinking it did not matter, maybe but never a card carrying electrician.

    Look at the panel box. Pull the cover so you can see inside. Keep your hands out of the box.

    Find the breaker that feed your outlet. Where is the black wire connected, on the Neutral Bus or on the Breaker. As soon as you can answer that, get back to us and let us know.
    tkrussell's Avatar
    tkrussell Posts: 9,659, Reputation: 725
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    #4

    Dec 28, 2007, 02:54 PM
    The wires should be checked to determine which is live and which is neutral, and do not assume that white is neutral and black is live.

    This condition should be corrected through out the home.

    The issue may be as simple as the wires are switched at the panel, as suggested by Don, however, if this is found to be the cause, be sure to re-check each outlet and light, as some the outlets may had been wired correctly, and now would be incorrect.

    As I suggested, all the lights and outlets in the home needs to be checked, as reverse polarity can make the screw shell of light fixtures and lamps live.

    Switches also, need to be checked to insure that no neutrals are being switched.

    This is a serious condition that needs to be resolved thruout the home.
    KISS's Avatar
    KISS Posts: 12,510, Reputation: 839
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    #5

    Dec 28, 2007, 09:27 PM
    As to some things that could happen if the problem is not corrected:

    1) Your TV can break because HOT might be connected to the coax shield.
    2) A shock hazard as in the above case
    3) Electrical devices will be switching the neutral rather than line internally
    4) Systems designed to prevent RFI (Radio Frequency Interference) won't work.
    5) Phantom voltages can be generated from devices connected improperly because of how the RFI filters are constructed.
    6) The screw side of a lamp base would be hot.
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