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Thread: Random earth leakage problem

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    Random earth leakage problem

    For a few months now I have been experiencing random earth leakage problems - earth leakage switch tripping for no apparent reason. For a while it appeared to be both random trips and when plugging in a charger power brick for a laptop.

    I have now spent several thousand rands on replacing all sorts of things based on advice from sparkles, eg gate motor, pool pump, all day/night switches, plus I have had the garage/workshop rewired with a new DB and own earth leakage breaker because some of the problems occurred when the garage lights were switched on each day! Each of these faults was detected using a 'megger' (?).

    Interestingly I find that this still occurs BUT still trips in the house and not at the new EL breaker, despite all the feed from the house now via the new switch.

    I cannot find a sparky who can get me past this point.

    I understand that the combined effect of power bricks and ups units (I have several ups units powering essential systems in the office) can create a background earth leakage level that makes the el breaker trip at very low additional el loads?

    I would appreciate some diagnostic advice as this is now driving me nuts!

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    if it is a heineman 60 amp unit dated 2006 - 2008 i can understand...i have been having huge problems with heinemen 60 amp earth leakage units...to a point that i now longer install heineman earth leakage units....and the joke..heineman only offer a 1 year warranty...i wonder why.

    i had a simmilar problem in december...i managed to find the problem...a wire which was no longer used...but not diconnected...i managed to find all the other little issues in the house...like water in light fittings...gate motor and pool pump...must have been from all the rain we had...once all the little faults whre found...the earth leakage unit still tripped...i replaced the earth leakage unit with a different make and havent had a call sinc...i did test the new earth leakage unit with an earth leakage tester and it did trip at 25 mA

    an insulation resistance tester(commonly refered to as a "megger" which is a brand of insulation resitance testers ) is used to find insulation resistance issues...

    fluorescent light fittings are a common problem when connected to an earth leakage units...when they ignite (start up) they cause tripping issues...bad idea to have them connected to an earth leakage unit...but in saying that...all sabs regs must be adhered to at all times.


    sounds to me like the sparky has connected the new earth leakage in series...which is incorrect...it must be connected in parallel...believe it or not but this is a common practice...a quick way to determine whether the sparky knows what he is doing or not...

    i sympathise with you trying to find a good sparky...there are hundreds if not thousands of them out there but when it comes to anything more than chasing walls and connecting plugs...there are only a few good ones left.

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    Site Caretaker Dave A's Avatar
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    Has the earth leakage unit in the house been replaced?

    Nuisance earth leakage tripping sure is a PITA. Part of the problem is the fault that is causing the tripping never gets enough juice to really advertise where it is while on the earth leakage unit. My sparkies use the term "blow the fault clear." It involves taking the suspect circuits off earth leakage so that when the fault blows, it blows properly!

    Obviously needs to be done with due regard for safety issues, and I'm probably going to take some flack for even suggesting it - but sometimes it is the only way to find the fault.
    The trouble with opportunity is it normally comes dressed up as work.

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    Quote Originally Posted by BillH View Post
    For a few months now I have been experiencing random earth leakage problems - earth leakage switch tripping for no apparent reason. For a while it appeared to be both random trips and when plugging in a charger power brick for a laptop.
    There's no reason a laptop power supply would cause earth leakage, they're usually Class II appliances and don't even have an earth connection.

    Quote Originally Posted by BillH View Post
    I have now spent several thousand rands on replacing all sorts of things based on advice from sparkles, eg gate motor, pool pump, all day/night switches, plus I have had the garage/workshop rewired with a new DB and own earth leakage breaker because some of the problems occurred when the garage lights were switched on each day! Each of these faults was detected using a 'megger' (?).
    Assuming the electrician removed the garage subDB from the RCD (earth leakage breaker) in the house when he fitted a new RCD in the subDB then this rules out the garage as being the problem. If the garage is still supplied via the main RCD in the house then without discrimination it's a lottery which one would trip fiirst to a fault in the garage.

    Quote Originally Posted by BillH View Post
    I cannot find a sparky who can get me past this point.
    This seems to be your problem. You need someone who's capable of localising and fixing this problem. You're going to have to get past the cheapest price mentality and find a good capable electrician and pay him his extortionate labour rate to find the problem.

    Quote Originally Posted by BillH View Post
    I understand that the combined effect of power bricks and ups units (I have several ups units powering essential systems in the office) can create a background earth leakage level that makes the el breaker trip at very low additional el loads?
    Firstly there's no such thing as background earth leakage. There's just earth leakage.... period. Earth leakage is usually measured in milliamps unless there's a lot of it and then it might be measured in amps.

    Secondly class2 appliances (double insulated) such as cellphone and laptop chargers would have zero earth leakage. A UPS usually has a chassis with an earth so with the UPS it's possible to have a low insulation problem resulting in earth leakage. It is unlikely however and would easily be proved using a Mega tester.

    Quote Originally Posted by BillH View Post
    I would appreciate some diagnostic advice as this is now driving me nuts!
    My immediate diagnosis is that you need a decent electrician otherwise your prognosis is looking bleak.

    RCD nuisance tripping is one of the more difficult problems to solve.
    Start with sorting out the easy stuff and only then get complicated if necessary.
    1 Ramp test both RCD devices.
    2 IR test all circuits on the main DB and fix anything with an IR value of less than 2 MΩ.
    3 Do same with Sub DB in garage.
    4 Check both DB's for circuits with borrowed or crossed neutrals.

    One thing you can do is keep a log of every time the RCD trips. Note the time of day, exactly what appliances are running and any other circuit breakers that trip at the same time.

    Can you attach photos of the inside of the main and garage DB's?
    Can you tell us whether the RCD resets first time after it trips?
    The more info you can give the better.



    Quote Originally Posted by murdock View Post
    fluorescent light fittings are a common problem when connected to an earth leakage units...when they ignite (start up) they cause tripping issues...
    If fluorescent light have low IR readings then they're faulty. A fluorescent light should present no earth leakage even during ignition cycle.

    Quote Originally Posted by Dave A View Post
    My sparkies use the term "blow the fault clear." It involves taking the suspect circuits off earth leakage so that when the fault blows, it blows properly!
    Not sure what 'blow the fault clear' means but the phrase is exciting in a very scary sort of way.
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    Thanks very much for your response. I can respond to the issues you raise as follows:

    The earth leakage switches are both Heineman but I have no idea as yet re their manufacturing date. Will look tomorrow. I was not aware that there are other makes? Can you recommend what I should buy?

    The fluorescent lights did not trip today - first time for a while after the sparky said he found loose connections in the switch yesterday.

    The only trip I have had today was when I plugged one of my microscopes (I am a biologist) into a multi-plug. Not sure how this could happen as this only powers the lamp and it's a new scope.

    Multiplugs are so necessary but seemingly problematical. Is it possible to buy good quality multiplugs that have an in-built trip switch?

    The sparky did not disconnect the sub-board feed from the trip switch in the house. I assume this is what you mean by in series? I did ask him why I assumed he would have by-passed the house trip. He indicated that this was how it should be done.

    I would really like to find a knowledgeable electrician. The guy I am using now was recommended by Geyserwise, before that I was using a "reputed" Somerset west company who eventually just stopped coming back. They have not been cheap either, plus they have recommended a lot of expensive replacements of stuff that turned out to have not been the problem.

    I am open to any recommendations for a good sparky in the cape town area - or an electrical engineer who does fault finding!
    Last edited by BillH; 06-Jan-12 at 08:42 AM.

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    Yes, it was replaced quite early in the process.

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    Thanks for your time to respond so comprehensively.

    I found a USA forum where someone found that different laptop power bricks tripped his circuits from different points in his house. This is exactly what I have been experiencing. The forum responder said that this was common and that with many such units plugged in renders the earth leakage more sensitive. Seemed logical at the time - some transformers give quite a buzz if you touch the wall socket end when disconnecting?

    I urgently need to find a good electrician who can fault-find in a scientific manner?

    We have kept logs for a while but could not link the faults to any appliance switching on or off. We have three types of occurrence: entirely random, plugging in a charger or the garage light issue. The random could be ants or geckos but we cannot find where if this is the case. Maybe a frayed wire underground somewhere.

    Thanks again!

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    I forgot to add that the earth leakage resets immediately.

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    Hi again,

    In response to the make of earth leakage switch, they are not Heineman (my mistake) but are marked "CBi". Most of the other breakers on the boards are SAMITE, with one or two Heineman switches left over from the original DB when we built the house 30 years ago.

    Is the CBi make OK?

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    Ok, today (Friday), had a random trip around 08:00 and the garage lights again tripped the house RCD and not the new one in the garage!

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