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GFCI /outlet tester

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  • GFCI /outlet tester

    I just acquired a new toy.

    For years I used the typical 3 neon outlet tester ...OK, no ground, reversed polarity...etc.

    I never really had a GFCI tester....I simply relied upon the self test button.

    Well the other day I came across the KLEIN RT250 GFCI receptacle tester with LCD display.

    You can see a number of reviews and operation of the device on u-tube.

    It is alive! as it uses two AAA batteries.
    About twenty dollars American at Home Depot.

    You get an English display telling you about the receptacle under test.

    Wired correctly, open ground, open neutral, open hot!, open neutral and hot, reversed hot/ground,
    and reversed hot neutral....That is more than the typical 3 neon tester.

    Then you get a GFCI tester....The device injects 6-9 ma of fault current yeah higher than what the NEC tells us
    but this is a "tester"....
    Here is the cool part... when it faults the GFCI it tells you pre-test voltage and how fast it faults....I have a GFCI that faulted in less than 0.1
    seconds! Is this important? Well I now believe so. I also had a GFCI outlet that would fault when the test button on the
    outlet was pressed, but would not fault using the KLEIN tester. If the fault time is greater than say 6 seconds the unit flashes
    and you now know the GFCI is actually faulty or miswired [mine was correctly installed] and needs to be replaced!

    The display also has about a 10 second time out, this allows you to insert the tool upside down or the display not
    facing you..Then you remove the tester and read the information.

    My whole approach to testing outlets has entered the 21st century.

    Now a question.....Other than you folks in biomedical electronics / medical electronics
    do you ever measure the pounds of pull on receptacles in the home or commercial environment?

    Cactus Man

  • #2
    How fast should a properly working GFCI trigger a fault? I would guess that 1 or 2 seconds of an electric shock might cause a person to lose muscular control and collapse.


    • #3
      IIRC a Class A GFCI should trip at between 4 to 6 mA and the time is less than 20 ms.
      Other class GFCIs used on circuits other than 120V, 15A or 20A have slightly higher trip levels.

      On construction sites even 460V welding machines need a GFCI, and those puppies are not cheap.
      I bought a bunch of them for a project I was working on years ago. They were around $400 each
      and I bought 60 of them.

      Using the GFT2G tester made by Hubbell can be manually adjusted for trip current stepping it up one milliamp at a time to see where the device does trip. The GFT2G sells for about $125 online.

      Note that OSHA does not require the use of a tester. They say the devices' internal test mechanism is good enough. Read about it here.
      But also note that this OSHA interpertation letter was written back in the early 90s and much more sophisticated testing equipment is available today 30 years later.
      Attached Files
      Last edited by Bob D.; 01-03-2021, 06:26 AM.
      "It's a table saw, do you know where your fingers are?" Bob D. 2006
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