Sparks while changing outlet with circuit breaker off

Discussion in 'Electrical Forum discussion & Blog' started by DavidV_NC, Dec 26, 2013.

  1. DavidV_NC

    DavidV_NC New Member

    Messages:
    7
    Location:
    Charlotte, NC
    I just purchased a 1970 house with aluminum wiring. I'm going to replace the old outlets with aluminum-rated ones. I just went to replace the first one and when I had the circuit breaker off and was disconnecting wires, the neutral wires started sending off sparks when they shifted. They continued to do this after the hot wires and ground were disconnected. My multimeter indicated there was no current going through the outlet.

    I assume the sparks indicate a problem, but I'm very much a novice when it comes to electrical work. Any help in figuring out what might be wrong would be appreciated. I did finish up installing the new outlet, as I figured that was safer than having loose wires.

    Bonus question: When getting the wire under the screws on the new outlet, I couldn't help scratching it a bit with my pliers. I've heard that scratches are particularly bad in aluminum wiring because it becomes a weak point during later heating and cooling expansion and contraction. How much of a problem is light scoring along the surface of the wire?

    Thank you.
  2. kcodyjr

    kcodyjr New Member

    Messages:
    103
    Location:
    Chelmsford, MA
    That sparking bothers me. I think one of two things must be going on;

    1) some other circuit is so badly miswired it's sending return current down another circuit's neutral line. if this is the case, something had to have been flickering, somewhere in the house, while that sparking was going on.

    2) somewhere on that same circuit further away from the panel, neutral and ground are tied together. that should only happen at the panel, and even at that, there are exceptions such as mobile homes.
  3. houptee

    houptee Member

    Messages:
    182
    Location:
    Monmouth County, NJ
    First thing go Look at the main panel to see if you have a ground wire to a cold water pipe, or to ground rods outside to make sure your panel is grounded.

    There must be a circuit in your house using the same neutral wires feeding back to the panel that you are working on, but it gets its hot feed from another breaker, so when you separated all the white neutrals in the box you broke the neutral circuit which has current flowing and hence the sparks.

    If you have coming into your panel any romex wires with 3 conductors Black Red White and a bare ground, then you have a "shared neutral" with the black and red wire breakers so watch out turn both breakers off or your gonna get shocked.
  4. hj

    hj Moderator & Master Plumber Staff Member

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    26,626
    Location:
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    You could have a failed neutral line and the ground is acting as the neutral, which means it is carrying a load, but your multimeter might not indicate it depending on HOW you are testing it.
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
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    Location:
    New England
    Unless you have an inductive (clamp-on) ammeter, or you insert the meter in series with the load, or have a known resistive load you can measure voltage across, you cannot test for current with a voltmeter or a multimeter. To get sparks, there has to be current. If the breaker was off, then it may not be fully disconnecting the line from the circuit. Or, as was mentioned, it was a circuit with a shared neutral, and they did not use the proper CB to shut both sides of the circuit off. Or, there is some other fault in your wiring.
  6. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,534
    Location:
    North Carolina
    it is called a multiwire circuit. Two hots sharing one neutral and was very common it its day
  7. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,626
    Location:
    Cave Creek, Arizona
    quote; Two hots sharing one neutral and was very common it its day

    Even so, THAT would not cause sparking of the ground wire.
  8. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    3,973
    Location:
    NW Ontario, Canada
    Not sure how this morphed from neutral to ground. Mind you, lots of folk confuse the two.
  9. Reach4

    Reach4 Active Member

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    2,233
    Location:
    IL
    I suspect you are saying that you get sparking when you touch the neutral (white) and protective ground (bare or green) together or when you bridge those two wires together with something metal-- such as a screwdriver. Is that what you are saying? If not, describe further what the sparking is between.

    Regarding "current", that represents a flow of electricity. That is measured with the amps or milliamps ranges on a multimeter. Often milliamp meters read zero in those ranges because the internal fuse was blown long ago when somebody probed an AC line voltage or a battery while in a current range rather than a voltage range. Be careful to only be in a voltage range when probing power wires, until you are sure there are no voltages present. I think you probably meant voltage when you said current, but your multimeter does have non-voltage ranges.
  10. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,126
    Location:
    Houston, TX
    Reading;

    "the neutral wires started sending off sparks when they shifted."

    That tells me that there is a loose connection also, and the wires are not secured properly.


    A person needs to cut the end of the wire Off and make the connection using a fresh bite on the clean undamaged conductor.


    Be careful playing with electricity.
  11. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    3,973
    Location:
    NW Ontario, Canada
    Yes, and I still see it used to this day. If the return path of the neutral is broken, the two loads end up in series. This can result in a voltage and current potential on the neutral. Even if the return is not broken, a grossly imbalanced load could see a small potential on the neutral because of line resistance. In extreme cases, this imbalance can go all the way back to the transformer but the bonding of neutral and ground at the service entrance is supposed to mitigate that. I have seen where an open neutral to the transformer resulted in so much current on the ground that was connected to a copper water line, that it warmed the water in the pipe.

    In the case of a "kitchen split", the two breakers are normally ganged together so turning off one side would also turn off the opposite side.
  12. houptee

    houptee Member

    Messages:
    182
    Location:
    Monmouth County, NJ
    You may want to consider running all new copper wire in the house if feasible and you can afford it.
    Last week a home burned down near me and they say due to aluminum wiring.
    Or if you decide to leave it in place you can pigtail each outlet with 6" pieces of copper wire and splice to your aluminum wires with special purple wire nuts made for that purpose.
    This lets you tuck the aluminum wires neatly back into the box with good tight connections and the device (receptacle or switch etc) can be pushed in and out flexing only the copper pigtails with much less chance of repeatedly flexing the existing aluminum wires.
    The drawback to this is those Cu-Al purple wire nuts are very expensive.
    http://www.idealindustries.com/products/wire_termination/twist-on/twister_al-cu.jsp
  13. kcodyjr

    kcodyjr New Member

    Messages:
    103
    Location:
    Chelmsford, MA
    This. The only wire that sucks worse than aluminum is old aluminum. Tearing all your walls open might not be practical, though.
  14. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,126
    Location:
    Houston, TX

    That may be a good Ideal. But good luck getting a extra 6 inches of copper in the outlet box.

    Cost should be no object when it comes to electrical safety.
  15. Reach4

    Reach4 Active Member

    Messages:
    2,233
    Location:
    IL
    What does that tell you about what the arcing is between? Or are you seeing sparks emanating from a point in the wire in all directions like a sparkler?

    If a loose connection explains sparking when the breaker is off, then the wire is carrying current. The shared neutral explanation of jwelectric and hj make sense. If there are two neutral wires using the outlet's terminals as a connection point and that connection is opening up intermittently, there can be arcing. Is that what your reading reports?
  16. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,126
    Location:
    Houston, TX

    My reading is that there is more than one problem.

    And some people should not be playing with electricity. Myself included.


    Sorry.
    Last edited: Dec 27, 2013
  17. DavidV_NC

    DavidV_NC New Member

    Messages:
    7
    Location:
    Charlotte, NC
    Thanks everyone. That was a lot to digest...

    First, Reach4, you're correct. When I said "current" I meant voltage. Still learning the terminology... Thanks for clarifying for me.

    The neutral wires were the ones sparking, both before and after I disconnected the hot wires and the ground wire. They sparked when I moved the outlet so they shifted slightly. They were still screwed in to the old outlet at that time and they were sparking off metal parts in the outlet itself. I was not shocked at any point, and I was careful to avoid creating a bridge between any two wires.

    Incidentally, I don't know if this is helpful information, but the grounding is copper water pipes. Also, I'm discovering the wiring is quite random, with parts of rooms on different circuit breakers.


    So is the only safety concern with a multiwire circuit the potential to be shocked if there's current you don't expect? If I turn off power to the whole house while I work, is there anything else I need to be concerned about, i.e. safety issues from the setup itself, even when I'm not working on it?

    And thank you, everyone, for the warnings regarding aluminum wiring. I'm aware of the safety issues and I'm trying to make it as safe as possible without spending money that I don't have. I'd like to replace with copper, but that's not feasible right now. An electrician friend recommended the aluminum-rated outlets as a good temporary measure?
    Last edited: Dec 27, 2013
  18. houptee

    houptee Member

    Messages:
    182
    Location:
    Monmouth County, NJ
    The purple al-cu wire nuts are $19.96 for a 10 pack at big orange store so that's $2 bucks per wire nut.

    That money would be better spent replacing the aluminum wire with copper wire if he can do it is what I am saying.

    Then you can use regular off the shelf wiring devices, connectors, etc, once you are all converted to copper.
  19. houptee

    houptee Member

    Messages:
    182
    Location:
    Monmouth County, NJ
    The purple al-cu wire nuts are $19.96 for a 10 pack at big orange store so that's $2 bucks per wire nut.

    That money would be better spent replacing the aluminum wire with copper wire if he can do it is what I am saying.

    Then you can use regular off the shelf wiring devices, connectors, etc, once you are all converted to copper.
  20. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,126
    Location:
    Houston, TX
    David,

    Your copper water pipes should not be carrying current.

    You should kill all power to the house, until you can map your new houses electrical system wiring.

    If you know how it is wired, then it is easy to fix later down the road.

    Current kills you, Voltage just tickles.


    Be Safe. Have a Happy New Year.
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