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Thread: GFCI tripping

  1. #11
    Join Date
    Nov 2006
    Location
    Texas
    Posts
    112
    Quote Originally Posted by JohnJ0906 View Post
    Do you have a leakage current clamp meter?

    At least you would be able to say whether or not it is the machine that is the problem, and let the appliance guys deal with it.

    I dont have such a clamp meter. The crude amp meter I have shows around 9 amps in and 9 amps out. I suppose the leakage current would show up on the ground wire. I do have a fluke 87 (no clamp) which I could get in series with the ground while the machine is running and maybe detect the leakage.

    How what is the threshold that makes the gfci breaker trip?

  2. #12
    Join Date
    Jun 2003
    Location
    NE (9.1 miles @5.07 Degrees from Winged Horses)
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    5,942
    Quote Originally Posted by Billy_Bob View Post
    Which parts were causing the trouble?
    There were one or two temp sensors that clamped to the refrig line. The epoxy had split and was allowing moisture to accumulate in the switch and thus to ground.
    Tom
    TBLO

  3. #13

    Something to think about?

    :confused: Issue with polarity, Hot? Neutral? I have had GFCI trips from “Series GFCI’S”

    :rolleyes: To even suggest bypassing a Safety when problem is known, in a public place no less.
    Commmeted “ Next step is to install a disconnect and hard wire the icemaker to non GFCI ckt. I'm a big believer in the life saving attributes of GFCI's. I would remove the GFCI protection only as a last resort.”


    422.51 Cord-and-Plug-Connected Vending Machines.
    Cord-and-plug-connected vending machines manufactured or re-manufactured on or after January 1, 2005, shall include a ground-fault circuit interrupter as an integral part of the attachment plug or be located within 300 mm (12 in.) of the attachment plug. Older vending machines manufactured or remanufactured prior to January 1, 2005, shall be connected to a GFCI-protected outlet. For the purpose of this section, the term vending machine means any self-service device that dispenses products or merchandise without the necessity of replenishing the device between each vending operation and is designed to require insertion of a coin, paper currency, token, card, key, or receipt of payment by other means.
    FPN: For further information, see ANSI/UL 541-2005, Standard for Refrigerated Vending Machines, or ANSI/UL 751-2005, Standard for Vending Machines.
    Goroon

  4. #14
    Join Date
    Jul 2008
    Posts
    774
    We had a problem similar to this in a state prison and we finally traced the problem to the limit switch that shuts the ice machine down when full. Every time they called us the machine would be empty! The control circuit that detected the ice bin full had moisture in the sensor and would trip the GFIC. The State would not let us hard wire the unit due to someone getting killed on another unit in their system! They suggested disconnecting the limit switch--which we did--they next morning their kitchen had about a pickup truck load of ice on the floor. We then installed a remote temperature probe thru the top of the bin and set it at 32 degrees--that did the trick!

  5. #15
    Join Date
    Apr 2008
    Location
    Ann Arbor, Michigan
    Posts
    4,718
    090125-1251 EST

    Cody K:

    The GFCI is required to trip at 5 MA of unbalanced current between the hot and neutral lines. Inside the GFCI is a small current transformer that these two lines pass thru. The output of this small current transformer is the difference in current between the two lines. This signal when larger than 5 MA is used to trip the GFCI. At 5 MA it may take several seconds. Higher difference currents will trip it quicker.

    For you to make your own measurement you need an adapter cable that will allow you to separate the hot and neutral from the ECG wire. The low range clamp on current probe has the hot and neutral run thru it and then you will read the difference current between the hot and neutral.

    To measure the current in the EGC is insufficient because the leakage current may follow some other path such as the water pipe.

    I believe Fluke makes some appropriate current transducers that connect to your DVM. Make it part of the expense to the customer. From years back I have from Fluke both a normal current transformer, and a Hall device type that plug into my DVM.

    I have not experimented with this idea, but it might work for your purpose. Open a GFCI, find the current transformer output, attach a pair of leads, and wire this to serve as your difference current transformer. It is a little more complicated, but this is the basic idea. This is not isolated from the AC lines. If you want to do this type of playing, then you need more instruction. I have to leave just now.

    .

  6. #16
    Join Date
    Feb 2003
    Location
    Bremerton, Washington
    Posts
    6,696
    A GFCI trips between 4-6 Ma and above. Its least likely to be the GFCI, and its doing its job. The leakage could be 100 mA which is more than enough for a fatal shock.

    There are availble GFCI testers that create an adjustable amount of leakage. Those are a good way to very GFCI issues.
    Moderator-Washington State
    Ancora Imparo

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