Hot on both sides of dedicated outlet ?!?

Discussion in 'Electrical Forum discussion & Blog' started by Theodore, Oct 20, 2020.

  1. Theodore

    Theodore Member

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    New York
    Remodeled kitchen 3+years ago. Refrigerator is a dedicated 15amp line with NOTHING else on it, as per code of course. No earthquakes have occurred and no one has messed with the wiring for years. This morning the refrigerator stopped working but I figured out it still functions on another outlet. And, after testing with voltmeter, I found that the dedicated outlet for the refrigerator reads 120V on the hot side (to ground) AND on the neutral side (to ground). The circuit breaker in the basement seems to be working fine and is not warm to the touch or anything weird. What can be going wrong?? For safety, I've now shut down the circuit from the breaker.

    Advice greatly appreciated.
    Theodore
     
  2. LLigetfa

    LLigetfa DIYer, not in the trades

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    How many wires on the outlet. Sometimes outlets are wired as "split" with two breakers for the outlet. Post a picture of wires on the outlet.
    Is there anything connected to the outlet? Is there more than one outlet on the breaker? It is possible that there is a load connected and the neutral return is open so the load is presenting a voltage on the neutral.
     
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  4. Theodore

    Theodore Member

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    There is no other outlet on this dedicated 15amp circuit breaker.
    I'm 100% certain because I oversaw its installation from kitchen to circuit breaker panel.
    It's a 3 wire (black, white, green ground) wire outlet.

    IMG_9439.JPG
     
  5. Reach4

    Reach4 Well-Known Member

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    A break in the neutral path could explain your symptoms. Can you find the other end of the white wire? But wait....

    It looks to me as if the jumper between top and bottom sections of the outlet may be broken out. If I am right, you would need to plug the fridge into the bottom socket. Let's see a picture of the other side of that outlet.
     
    Last edited: Oct 20, 2020
  6. LLigetfa

    LLigetfa DIYer, not in the trades

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    Thanks for the pic. Where are you referencing the ground, the green wire or the metal box? Did you check for voltage between the green wire and the metal box? I don't see the green wire bonded to the metal box. Is the wire in metal conduit for the full run to the panel?

    Can the white-to-green circuit provide any current?
     
  7. wwhitney

    wwhitney Well-Known Member

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    I suggest rechecking your measurements with a (edit) low impedance meter. Or one of those plug in receptacle testers.

    Cheers, Wayne
     
    Last edited: Oct 20, 2020
  8. Theodore

    Theodore Member

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    Jumper is intact (just bad photo lighting).

    I disconnected the hot and neutral and turned breaker back on.

    I got:
    • 121.1 V from black to green
    • 121.1 V from white to green
    • 0.88 V from black to white
    • 0.0 V from green to the metal box.
    The green wire is bonded to the outlet, but not to the box.
    The wire is armored cable from this box to the circuit breaker panel.

    I am pulling what little hair I have left out. Makes no sense to me that on a random Tuesday morning, a fault could develop that not only makes the neutral hot, but simultaneously prevents the neutral from tripping the breaker?! FWIW, the wife was already in morning work routine and heard the fridge compressor working curiously loud this morning at 5AM, and then minutes later she said it was silent and she went to open the door and the light was out. Fridge works fine in adjacent outlet (different circuit). I subsequently pulled the fridge outlet to discover per details above. Again, makes no sense to me.

    IMG_9440.JPG IMG_9445.JPG
     
  9. Reach4

    Reach4 Well-Known Member

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    Either the white wire is broken or came loose from the neutral strip in the breaker box, or the green wire is broken or came loose from the grounding strip in the breaker box. The fact that the fridge stopped working would point to the white neutral rather than green. Neutral and grounding may be on the same bar.

    Or if you have one of those newfangled breaker boxes where the neutral comes through the breaker, -- well you know.
     
    Last edited: Oct 20, 2020
  10. LLigetfa

    LLigetfa DIYer, not in the trades

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    If it were not armored, I would suspect rodent damage, too tight a bend or staple, or some other damage has shorted the neutral to hot which also burned off the neutral to panel bond. This is less likely to happen if it is one contiguous armored cable run.

    Possibly the neutral is open at the panel and your meter is very high impedance or you are using a contactless probe that can give a false hot reading. A floating neutral can pick up stray voltage just from proximity which was why I asked if it can actually supply current. A lightbulb in a pigtail socket makes for a good tester. If connecting it between green and white does not light the bulb but connecting between green and black does, then you have an open neutral.
     
  11. Theodore

    Theodore Member

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    Going off your suggestions: i used a lightbulb in a pigtail socket. Black to Green gives full/bright light. White to Green gives a barely visible/very weak light. Does this reinforce any theory?
     
  12. LLigetfa

    LLigetfa DIYer, not in the trades

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    Interesting... A small current potential suggests something more than an open neutral at the panel on just that one circuit.

    More likely damage along the route and possible moisture as well. Possibly a poor neutral bond between the panel and the pole and/or a badly balanced panel with much more current on one leg than the other.

    Still, I would rule out an open neutral inside the panel first. Might be time to call an electrician.
     
  13. Reach4

    Reach4 Well-Known Member

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    Lightbulb was LED I suspect.

    If LED, I tend to think white wire is broken, but if it is a tungsten bulb that glowed dimly, then make that a marginal connection for the white. Find the white in the breaker panel. Tighten the place that white connects.
     
  14. wwhitney

    wwhitney Well-Known Member

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    More precisely:

    -Shut off power upstream of the panel so that no live parts are exposed in the panel.
    -Inspect the connection for signs of discoloration, which would imply overheating. If present, report back for further guidance.
    -Tighten to the specified torque using a torque screwdriver. If it's a neutral bar in the panel, the panel label should specify the torque. If the neutral is going to the breaker, then imprinting on the breaker case should specify the torque.

    Or call an electrician if any of the above doesn't feel comfortable.

    Cheers, Wayne
     
  15. Theodore

    Theodore Member

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    It's a tungsten bulb that was glowing dimly.
    I'll look for a loose connection at the panel, i guess......
     
  16. wwhitney

    wwhitney Well-Known Member

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    If you're able to safely measure the voltage drop across the tungsten bulb while it is connected between neutral and ground, that may be informative.

    Just to double check: only the refrigerator circuit is acting weird? No other unusual electrical issues? And did you make any house modifications in the recent past?

    Cheers, Wayne
     
  17. Theodore

    Theodore Member

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    Just wanted to close the loop on this, I hope. Had an electrician friend come over this evening. We found one junction box in basement where this line connects to. We opened, undid the wire nuts and reconnected them. No idea if that was the culprit or not. Everything works like there's never been an issue. He suspects there must have been a broken neutral somehow in that junction box that has now fixed itself. Maybe the wires in the wire nuts were a little dirty. It's all armored cable, so rodent damage is not possible. All neutrals in main panel were super-tight to begin with. We both sort of shrugged and said let's wait another 3+/-years and see if it happens again before taking more drastic measures (i.e. tearing open walls/ceilings to replace all).
    Thank you all for your kind and generous advice.
     
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  18. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    When there is no current flow (an open circuit), and something is plugged in, measuring between the hot and neutral is effectively the same as measuring on the same piece of wire, so when measuring to ground, you'd get the same measurement. When there is current flow across a load, then, you'll measure a voltage drop across it. So, measuring the same voltage on both sides of what should be an active load means it's an open circuit.

    The wire nut may have been loose, or one of the wires may not have been pushed in all the way, creating an open circuit. Just to make sure, once I've put the wire nut on, I like to pull each wire in there individually to ensure it doesn't come loose from the others. IF you pre-twist them, that shouldn't happen, but if you ensure they're all the same length, and you keep them all lined up when you tighten the wire nut, it should twist and lock them all in on their own.
     
  19. wwhitney

    wwhitney Well-Known Member

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    Right, but the OP's measurements (to my understanding) were taken with no load at the refrigerator receptacle.

    However, now we have the information about the basement junction box, and perhaps there is another load fed from that junction box (contrary to the original information in the OP). So the neutral wire nut in the junction box would have 3 wires under it, the feed from the panel, the refrigerator receptacle load, and the other unknown load. If that connection was compromised so that the feed from the panel was effectively disconnected, but the other two wires were still connected, then that would explain all the behavior described. The 120V neutral-to-ground measurement was through that other load, and the light bulb glowed dimly because it was powered in series with the other load.

    Cheers, Wayne
     
  20. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Data without knowledge can lead to misdirection. It's good to ask questions. The more you know, the more you know you don't know! One should strive to not make the same mistake twice, a mark of higher intelligence...
     
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