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Checking the voltage in a light bulb socket

  1. Apr 1, 2017 #1
    Hello,

    I was trying to check with a voltage tester if there was voltage in a light bulb socket (Edison type, no bulb present). Explosion happened (a relatively loud sound) and the safety circuit switch turned off.

    My question is, how can one explain this with the laws of physics and how can one check for voltage in such situation without explosion and turning off safety switch?

    Sincerely,
    Nikola
     
    Last edited: Apr 1, 2017
  2. jcsd
  3. Apr 1, 2017 #2

    berkeman

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    Staff: Mentor

    Glad you are okay and you just popped the breaker.

    You most likely shorted Line and Neutral in the open socket with your voltage probes. The outer screw-shaped conductor is Neutral, and the small button at the bottom of the socket is Line (when the socket is wired correctly). As you reached for the bottom button, you probably made contact with both the button and the outer threads with the metal part of that probe.

    http://images.esellerpro.com/2242/I/668/27/lamp gu10 to e27.jpg
    lamp%20gu10%20to%20e27.jpg
     
  4. Apr 1, 2017 #3

    berkeman

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    To do this test in a more safe manner, be sure to use probes that only have a very small amount of metal exposed near the end of the probe tip, with the rest covered by insulators.

    https://cdn.sparkfun.com//assets/parts/8/6/9/5/12078-01.jpg
    12078-01.jpg
     
  5. Apr 1, 2017 #4
  6. Apr 1, 2017 #5

    berkeman

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    Definitely. To temporarily use that probe until you get better ones, you could insulate most of that exposed metal probe tip with heatshrink tubing or electrical tape. Only leave about 1mm of the conductor tip exposed.

    Oh, and please be careful. Why are you wanting to make this measurement? Measuring the voltage at the wall socket is a bit safer, as long as you are careful not to touch any metal with your hands or body when you are making the measurement.
     
  7. Apr 1, 2017 #6

    berkeman

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    BTW, that looks like a small screwdriver to me. Where does the wire attach?
     
    Last edited by a moderator: May 8, 2017
  8. Apr 1, 2017 #7

    OK, thank you very much.
     
  9. Apr 1, 2017 #8
    Which wire?
     
  10. Apr 1, 2017 #9
    Btw, can you, or somebody else, suggest me some popular or semi-popular book (first year undergraduate university textbook also acceptable) which explains those things?
     
  11. Apr 1, 2017 #10

    dlgoff

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    It's a Neon Circuit Checker.
     
  12. Apr 1, 2017 #11

    berkeman

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    Staff: Mentor

  13. Apr 1, 2017 #12

    Averagesupernova

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    Gold Member

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