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Earth Leakage

Discussion in 'Hobby Electronics' started by jrobbo, May 22, 2004.

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  1. jrobbo

    jrobbo Guest

    Hi All,

    I have something in my house that is causing the Safety Switch (Earth
    Leakage Breaker?) in the switch box to switch off.

    This used to happen once a week or so, but then I went on Holidays for
    a month, and I went around the house and switched off a fair bit of
    stuff at the wall before I went, as well as the heaters. Of course,
    the power didn't go off once while I was away. Since I've been back
    home though, the power is going off once or twice a day.

    So, I figure it is one of the things I'd turned off while away, or one
    of the gas heaters. I've started going around unplugging things one by
    one, but it seems a bit hit and miss.

    Is there such a thing as a plug-in earth leakage breaker, that I could
    plug one piece of equipment into, and then plug that into the wall,
    that would trigger before the main breaker in the fuse box triggers?
    Something like this would make it easier to isolate the faulty item
    over time

    Any other thoughts? Any advice appreciated


  2. Yes, made by HPM (electresafe), PDL and Ringgrip among others, easy to
    come by, but whether it would trip first is hard to say.
  3. John_H

    John_H Guest

    Don't rule out it being a power outlet (wall socket) causing the

    Particularly if you've got one exposed to moisture -- or like to wash
    your walls with a garden hose. :)
  4. Hello John R,
    My next door neighbours had a similar problem. I managed to
    isolate the problem to their fridge. The reason I remember is,
    I had a long extension lead hanging out the window of my
    house going into their house for a month running their fridge
    and they wouldn't get off their backsides and find an electrician
    to fix the problem. I had to find an electrician and bring him to
    their house. Payment I recall was cartons of beer.

    There were three of these leakage detector devices fitted to
    that house. The electrician removed one and bypassed it.
    I remember him saying that it was OK to remove it because
    the house was old and they were fitted voluntarily. The
    electrician said he would come back and run a separate
    cable for the fridge back to the fuse box and refit the leakage
    device. I remember him saying that fridges are better off run
    on their own dedicated power circuit with no earth leakage
    device fitted.

    How does that little story help you? Well, put your fridge
    on a power circuit without a leakage detector then you
    can relax a bit knowing that your food will be OK, while
    you find, by trial and error, the appliance that is causing
    the problem.

    John Crighton
  5. If the appliance isn't too large you could run it through an isolation
    transormer. Better to fix the faulty appliance though. The device is there
    to protect you!

  6. jrobbo

    jrobbo Guest

    Thanks Marty,

    I absolutely want to isolate the faulty device so that I can fix it,
    there was never any question of doing otherwise.

    The problem I have is that most of the suspect equipment is the
    computer equipment in the office, ie. several computers, printers, a
    scanner etc. It's a PITA to turn one of the computers off for a couple
    of days to see if it is the culprit, as they get used fairly heaviliy,
    it's easier if I can isolate single appliances while still using them
    to identify the faulty item, then I can get it fixed and be done with


  7. jrobbo

    jrobbo Guest

    Thanks Patrick,

    I'll give one of them a go


  8. David Sauer

    David Sauer Guest

    Here's my 2cents.

    Check your switchboard to see if you have a dedicated circuit such as
    for the fridge or freezer that doesn't have RCD protection. (These
    days its required on everything). If you do, then go out and buy one
    of those portable RCD protectors (they can cost quite a bit however do
    come in handy) and run the suspect items off an extension lead plugged
    into the unprotected outlet. Use the portable RCD on the extension
    lead to try and determine the faulty device over time.

    Another point is that some houses only have 1 rcd to do all the
    outlets in the whole house, so if you have an item that is slightly
    leaking (anything with a heating element will) can add up and cause
    the RCD to trip. It is recommeded to have an RCD for each
    power/lighting circuit within the house that way if it trips it only
    turns off one circuit. Stops the accumulation of slightly leaky

    In fact there is no reason why you cannot do away with RCDs at the
    switchboard and just use GPOs with RCDs fitted, however this is a very
    expensive option.
  9. Another pretty sure fire method would be to go around and measure the
    insulation resistance with a 'Megger' type meter. Anything with a low
    reading say below 1 megohm would be suspect. The faulty item would show up
    compared to the other stuff. An intermittent fault would not show up with
    this test but it would be a logical start.
  10. I remember I plugged my electresafe into a shaver socket (which in NZ has
    an isolating transformer inside it), for some reason the electresafe blew
    up under no load, totally cooked itself.
  11. Paul Howard

    Paul Howard Guest

    Yeah! Good move. Megger the PC, the printer, VCR and TV. Should help
    find the faulty item, or stop them from ever working again :p

  12. David

    David Guest

    Hi John,

    A common cause is the fridge. If the fridge has auto defrost, this often
    runs from a timer within the fridge, and operates one / twice a day. When
    this turn on it defrosts the fridge and heats up the water to
    evaporate it. If the heater has developed leakage, which is quite common,
    this will trip a RCD (or Safety Switch).

  13. YEAH, it was said hoping the operator had a clue about instruments, but then
    again they could ask the 'armchair experts' like yourself .
  14. Rod Speed

    Rod Speed Guest

    But some appliances have a bit of leakage that is perfectly safe.
  15. Jon

    Jon Guest

    I'd try the fridge, the washing machine and the dryer as likely culprits
    from experience. Forget about the printers and computer monitors.. Theyre
    usually ,but not always double insulated. They cannot t rip the earth
    leakage detector. A megger test with POWER OFF to power points, would be a
    good idea, as well as checking your power point with an el cheapo phase
    tester to make sure all is well with your power points.
    Megger test all appliances that are not sensitive to Meggers. I once found a
    temp caravan which was giving trouble with earth leakge due to moisture
    building up in winter and bad wiring from extension leads.
    Watch out for home owner wiring. It lethal!!!!
  16. James

    James Guest

    text cut to save space

    the fridge and heats up the water to
    Mornin all,

    According to some people at clipsal I was speaking to, the toaster is
    often likely to trip the RCD. This is even if it is not being used,
    just plugged into a power point. The elements are connected to the
    neutral all the time and if there is a voltage build up (say when a
    fridge starts) some current may leak from neutral to earth in the

    ANother thing it could be is just cumulative leakage, small amounts of
    leakage in a lot of places. It is good practice to install a separate
    RCD per circuit rather than one for the entire installation. This
    costs more but is much less prone to being a pain. While the RCD's are
    rated at a leakage current of 30mA they are usually set to trip at
    22mA in the factory to keep them in the middle of the allowable

    Like other posters have said, some appliances do leak normally to
    earth and having them on separate RCDs can help. Some have caps or
    MOVs connected between active and earth too which will cause some
    current to flow through the earth.

    goodluck finding it

  17. jrobbo

    jrobbo Guest

    Thanks very much for all of the excellent responses so far, the
    assistance very much appreciated.

    I don't think the fridge is the culprit, it was on the whole time we
    were on holidays (a month), and the power stayed on the whole time.
    Since I've been back, I've turned on everything that I had turned off
    while we were away (2 computers, monitors, printers, speakers, a
    scanner, a TV, DVD player, and amplifier, and two central heating
    systems, as well as sundry other devices), and the leakage breaker has
    started tripping at least once a day.

    I don't think it's the toaster either, as we don't actually have a

    Our house has five seperate power circuits, all fed by one leakage
    breaker. It also has five lighting circuits, all fed by another
    leakage breaker. There is a seperate circuit for the oven, and it
    doesn't have a leakage breaker. I wish I had thought ahead when
    building the house an specified seperate leakage breakers for each
    circuit, oh well, I might get them fitted later.

    Anyway, I may have found the culprit. I had my soldering station
    plugged in, but not turned on. I unplugged it yesterday morning, and
    the breaker hasn't tripped since then. I'll leave it for another week
    and see how I go. The soldering station is just one of those Duratech
    cheapies from Jaycar, I've had it for about 18months I guess. I might
    pull it apart and see if there is something obviously wrong with it.

    Thanks again everyone!


  18. Chas

    Chas Guest


    Sorry, I beg to differ. Any device with an SMPS will include an RFI filter
    in the power supply, resulting in an earth leakage of 2-5mA. The filter may
    be on the power side of the switch. A faulty filter component or multiple
    devices connected to one RCD could cause a trip.

    Regards, Chas.
  19. Residential RCDs in Australia should operate at 30 mA.

  20. Phil Allison

    Phil Allison Guest

    ** Double insulated devices ( lots of them have SMPS) have only a two core
    power lead with no connection to supply earth. Kinda makes earth leakage a
    bit unlikely.

    ............... Phil
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