Strange Coincidence, or wiring issue?

Discussion in 'General Electronics Chat' started by Sybarite, Aug 23, 2010.

  1. Sybarite

    Thread Starter New Member

    Aug 23, 2010
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    Hello,

    I'm new to the forum and hope that someone can help us. We moved in to a home that we purchased last December, that was built in the 60's. Over the past few months, several appliances and small electronics have just "burned-out" or stopped working:
    • Coffee-maker
    • Hair-dryer
    • Toaster overn
    • Foreman-style grill
    • Air purifier seems to turn itself off sporadically (safety circuit?)

    The first couple of failures I chalked up to normal wear and tear. But after multiple items have failed within such a short time, I've been convinced that it's more than a coincidence.

    The kitchen was slightly updated including what looks like newer wiring/circuits. I have no idea if the work was done by licensed electrician, or if the previous owner did it himself.

    We haven't done much to the electrical in the place, other than we swapped out a few outlets and switches with new ones that weren't painted shut.

    Could something we have done lead to prematurely burning out our small electronics? We would hate to ruin our new dishwasher, new fridge and new in-wall AC unit if there is something wrong with the overall wiring. What can I test for with my DMM?

    Thanks for any help you can contribute!
     
  2. tom66

    Senior Member

    May 9, 2009
    2,613
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    There's little you can measure with your DMM, other than the mains voltage. Stick the probes into a socket (while it is off), set to 200 volts AC (presuming your in the US), you should measure less than 10V (the switch does let a bit of current leak and the meter has a high enough resistance to see this), while on you should measure 100V to 127V. If it is out of this range then you have a fault and you should contact an electrician, or better, the utility.

    Some things however can just be a coincidence. The grill, for example. I take it there are very little "electronics" in it, just a heating element and maybe a timer (mechanical/electronic?) If so it is very difficult to fry a grill's heating element... not without melting everything else around it.
     
  3. Jaguarjoe

    Active Member

    Apr 7, 2010
    770
    90
    You could have a fault in the main neutral lead from the incoming power line. If you have poor contact between that neutral wire and the neutral distribution bar in your breaker panel, the 2 power phases (L1 and L2) will no longer be equal.
     
  4. Sybarite

    Thread Starter New Member

    Aug 23, 2010
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    0
    Right, the electric grill is a very simple device. I just don't know enough about electronics to know if an improperly wired circuit can cause it to fry, while not tripping breakers or showing any other symptoms.

    Thanks for your reply.
     
  5. Sybarite

    Thread Starter New Member

    Aug 23, 2010
    5
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    Hi Joe,

    Is there any easy way to test, measure or confirm this?
     
  6. Jaguarjoe

    Active Member

    Apr 7, 2010
    770
    90
    You should have duplex receptacles (one outlet above another). Plug in an appliance at the outlet giving you the problem. Probe the other outlet with your meter. If you get a reading substantially different than 120VAC you probably have this problem. Often the culprit is simply a loose connection in your breaker box.
     
  7. eblc1388

    Senior Member

    Nov 28, 2008
    1,542
    102
    Write a proper compliant letter to the power company, detailing the sequence of the event of appliance failure.

    Every power company has a duty to consumer to assure them that the line voltage is within specific limits. They have equipment to monitor the long term voltage fluctuation on the lines.
     
  8. creakndale

    Active Member

    Mar 13, 2009
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  9. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,574
    230
    I vote for the neutral problem. This happened to my father. Bulbs in certain light would last for months or days. Turned out it was a loose neutral at the pole. The difference in voltage between the two 120VAC branches will vary, depending on what is running on each branch at a given moment. Appliances turning on and off will show large changes.

    Ken
     
  10. Sybarite

    Thread Starter New Member

    Aug 23, 2010
    5
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    I actually do own one of those. Last night I tested the majority of the outlets in the kitchen circuit, they tested normal. However, when I tested a few in the dining and living room areas, they tested hot/neutral reversed.

    Could this be the culprit?
     
  11. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    If it indicates hot/neutral reversed, the wiring must be corrected.

    As has already been suggested, I also feel that you have a problem with the neutral as well. Another possibility is that the load on the service panel is very unbalanced; ie: lots of load on L1, little or none on L2.

    Please do not attempt to correct this yourself. Contact a licensed electrician to correct the deficiencies. You have multiple issues going on.

    Review the documents that you signed when you purchased the home. It's very common to have a 1-year warranty on the home. The previous owner should pay to have the deficiencies corrected.
     
  12. Sybarite

    Thread Starter New Member

    Aug 23, 2010
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    Hi,

    Thanks for your feedback. I think we will enlist an electrician's help, as this appears beyond our abilities as DIY'ers.

    This is an old home, and we did not get any warranty with the purchase. I don't think this is as common here in NJ.
     
  13. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,574
    230
    Beyond the problem with the hot-neutral reverse, that device won't tell you what you need to know if the problem in a loose neutral feed. You need an AC voltmeter to check the actual voltage at each outlet. And, the voltage will be different on each branch depending on what is running at that moment. This Again this is assuming a noose neutral.

    Ken
     
  14. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
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    You are 100% correcct, a loose neutral termination anywhere along the line can wreak havoc with your line voltage. Think about it - if you lose neutral then you've got 240V dividing across "Side A" and "Side B" of all the loads in your house. This can cause things like 90V on one side and 150V on the other.

    These type problems also tend to be intermittent. I'd call the power company, they're free and will tighten everything up to the breaker box.
     
  15. creakndale

    Active Member

    Mar 13, 2009
    68
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    I'd have an electrician in first to check all outlets/switches, connections and correct the problems. Only after that would I get the electric company involved. You don't need the them shutting off your electricity until the in-house problems are fixed. Talk about opening a potential "can of worms".

    creakndale
     
  16. BillB3857

    Senior Member

    Feb 28, 2009
    2,400
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    Although it needs to be corrected, I doubt that the hot/neutral being switched is causing your problem. I would also vote for the bad neutral connection either at the pole or at your entry point. One way to test is to place your voltmeter in a receptacle, as suggested in an earlier post, along with a fairly high current draw appliance. When you turn the appliance on, you should see a very minimal voltage change, if any. If the voltage drops more than a few volts, there is a good chance that the voltage on the other side of the line went up by the same amount. A poor neutral connection at a distribution point will do that.

    If you have noticed lights getting suddenly bright, then dimming back down to normal, that is a sure clue to a bad neutral connection.
     
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