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Shocks in Kitchen

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    #32
    mikeoneill893
    Site Banned Posts: 52 ✭✭mikeoneill893


    knipex wrote: »
    True..

    16mA or above can trip them

    the no-trip test is at 15mA


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    #33
    eggy81
    Registered Users Posts: 2,004 ✭✭✭eggy81


    2011 wrote: »
    No, not any current. Only a current >30mA should cause the RCD to operate.

    Anything over 15ma can trip them.
    They trip at between .5 and 1 times their rated current don't they?


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    #34
    Steve
    Moderators, Category Moderators, Entertainment Moderators, Sports Moderators Posts: 22,584 CMod ✭✭✭✭Steve


    eggy81 wrote: »
    Anything over 15ma can trip them.
    They trip at between .5 and 1 times their rated current don't they?

    Cheap ones do. Quality ones do what it says on the box - 30mA :)

    If you have RCDS with 16mA trip level then anything with a switch mode power supply will drive them nuts. Phone chargers, laptops, any modern electronics.


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    #35
    eggy81
    Registered Users Posts: 2,004 ✭✭✭eggy81


    Steve wrote: »
    Cheap ones do. Quality ones do what it says on the box - 30mA :)

    If you have RCDS with 16mA trip level then anything with a switch mode power supply will drive them nuts. Phone chargers, laptops, any modern electronics.

    I thought they were supposed to trip at between .5 and 1 times their current.
    This sheds some light on a problematic rcd I've been dealing with.


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    #36
    SpaceTime
    Closed Accounts Posts: 9,088 ✭✭✭SpaceTime


    They trip between 15 and about 22mA.


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    #37
    mikeoneill893
    Site Banned Posts: 52 ✭✭mikeoneill893


    "A Hager 30mA RCD will not trip at 15mA but will trip at a point above 15mA and below 30mA"

    http://www.hagerelectro.com.au/downloads-services-support/faq/84.htm


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    #38
    mikeoneill893
    Site Banned Posts: 52 ✭✭mikeoneill893


    i've never done any ramp testing so i'm not familiar

    maybe steve is right and they're calibrated for 30mA

    why the fubar should rcd's be tripping anywhere between 16-30 out of the box and not 30mA

    it's gonna create a lot more potential for nuisance


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    #39
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    mikeoneill893 wrote: »
    i've never done any ramp testing so i'm not familiar

    maybe steve is right and they're calibrated for 30mA

    why the fubar should rcd's be tripping anywhere between 16-30 out of the box and not 30mA

    it's gonna create a lot more potential for nuisance

    Not if 16 to 30 was always the average. Increased nuisance would only be noticeable if the average trip level did actually reduce compared to before.


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    #40
    mikeoneill893
    Site Banned Posts: 52 ✭✭mikeoneill893


    Bruthal wrote: »
    Not if 16 to 30 was always the average. Increased nuisance would only be noticeable if the average trip level did actually reduce compared to before.



    so the no trip test is 15mA......


    the trip test is at 30mA...........




    therefore rcds must trip at a point between 16 and 30mA


    (copyright einstein)


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    #41
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    mikeoneill893 wrote: »
    so the no trip test is 15mA......


    the trip test is at 30mA...........




    therefore rcds must trip at a point between 16 and 30mA


    (copyright einstein)
    Yea but unless we know the average of all RCDs in the country, it would be hard to say that finding out they trip at 20 for example, would mean more nuisance tripping than is usually seen.


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    #42
    mikeoneill893
    Site Banned Posts: 52 ✭✭mikeoneill893


    Bruthal wrote: »
    Yea but unless we know the average of all RCDs in the country, it would be hard to say that finding out they trip at 20 for example, would mean more nuisance tripping than is usually seen.
    ya i wasn't implying that


    i just meant less potential nuisance at 29 than 19 for example


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    #43
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    mikeoneill893 wrote: »
    ya i wasn't implying that


    i just meant less potential nuisance at 29 than 19 for example

    Yea that's true alright.


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    #44
    Steve
    Moderators, Category Moderators, Entertainment Moderators, Sports Moderators Posts: 22,584 CMod ✭✭✭✭Steve


    mikeoneill893 wrote: »
    so the no trip test is 15mA......
    the trip test is at 30mA...........
    therefore rcds must trip at a point between 16 and 30mA
    No, the trip test is 30mA. That's what the regulations / standards say.
    There is no defined 'no-trip' test, it varies my manufacturer.

    Also bear in mind that not all milliAmps are the same, it depends on the waveform of the imblance. A human being electrocuted, in theory, will produce a nice sinusoidal imbalance that is easy to work with. Other devices can create lesser RMS imbalances but with higher peaks that exceed the thresholds and this is where nuisance trips arise.

    If you really want to know the science of it, have a read of this.

    As I said earlier, better quality units are more tolerant because - and I'm guessing here - it's probably easier and cheaper to manufacture a device that trips *somewhere* between 16 and 30 mA than it is to manufacture a device that trips between 28 and 30mA.


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    #45
    Doom
    Banned (with Prison Access) Posts: 2,381 ✭✭✭Doom


    Are the pipes bonded to Earth...? Or maybe not tightened down enough, this may cause a poor earthing in the house.
    Your electrician should have done an earth continuity test...it would have shown up any earthing problems.


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    #46
    mikeoneill893
    Site Banned Posts: 52 ✭✭mikeoneill893


    Steve wrote: »
    No, the trip test is 30mA. That's what the regulations / standards say.
    There is no defined 'no-trip' test, it varies my manufacturer.

    yes trip test is 30mA....according to regulations



    no-trip test is conducted at 15mA is it not?


    it doesn't vary does it?


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    #47
    Steve
    Moderators, Category Moderators, Entertainment Moderators, Sports Moderators Posts: 22,584 CMod ✭✭✭✭Steve


    mikeoneill893 wrote: »
    no-trip test is conducted at 15mA is it not?


    it doesn't vary does it?

    I don't know, I don't actually do much RCD testing so I'll take your word for it.

    This tech note seems to suggest 62% of trip level as an acceptable no-trip test - in this case it would be 18.6mA for a 30mA RCD. Again, I'm not an expert on no-trip testing. :)


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    #48
    mikeoneill893
    Site Banned Posts: 52 ✭✭mikeoneill893


    neither do i

    but no-trip test is always 50% of rated trip current-it doesn't vary


    manufacturers tolerances do

    as you say the better quality rcds may be closer to 30mA trip on a ramp test


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    #49
    Steve
    Moderators, Category Moderators, Entertainment Moderators, Sports Moderators Posts: 22,584 CMod ✭✭✭✭Steve


    Anyways... better get back on topic. :D

    The only real way to sort the OP's issue is to do a proper earth loop impedance test on all exposed metalwork back to the incomer.

    It could be a broken neutral touching metal somewhere - it would explain the mild shocks as it would create a potential on exposed parts as it used the earthing system as a return to the neutralising link at the meter.


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    #50
    mikeoneill893
    Site Banned Posts: 52 ✭✭mikeoneill893


    prob the first thing you'd do alright

    loop impedance testing

    can't be much to it


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    #51
    adrian92
    Registered Users Posts: 563 ✭✭✭adrian92


    My first thought was to agree that it seems like static charge. Mildly but of no danger. I am still inclined to think it is this.

    I do not know if anyone else has suggested that you ensure your RCD (device to protect people if they touch a live part) - assuming you do have an RCD at your electrical Distribution Board.


    But there could be something else happening.

    Is there any time pattern to these occurences , have you noticed?


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    #52
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    Steve wrote: »
    It could be a broken neutral touching metal somewhere - it would explain the mild shocks as it would create a potential on exposed parts as it used the earthing system as a return to the neutralising link at the meter.

    If it was a broken neutral touching metal somewhere, that would be unlikely to cause any shocks, unless the earth on the metalic item was very poor. If it was poor, the item with the broken neutral touching it, would not be working properly.

    Even the full 230v direct might only cause mild shocks, if perceived at all, unless an earth or neutral point was also in contact with the person.

    An actual loop impedance test of all the sockets in the house might show a problem before even looking at exposed metal. If for example a shock is being perceived from the washing machine, then there is an earthing problem at its socket and likely other sockets (or machine itself) . A group of sockets with no connection to the earth bar for example, but all linked to each other, would all have a shared problem if an earth fault was on one appliance plugged in.


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    #53
    joeperry
    Closed Accounts Posts: 527 ✭✭✭joeperry


    Is the op still alive? What was the problem?


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    #54
    Andrew_Doran
    Registered Users Posts: 227 ✭✭Andrew_Doran


    It could also be a bad neutral before the neutralising link at the cutout (assuming TN-C-S), which would allow both earth and neutral within the installation to "float".


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    #55
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    Andrew_Doran wrote: »
    It could also be a bad neutral before the neutralising link at the cutout (assuming TN-C-S), which would allow both earth and neutral within the installation to "float".

    When/if that happens, items in the house wont be working properly and would be clearly not right, apart from if only very low wattage items are on.


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