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Thread: Earth Leakage Breaker (RCD) Tripping

  1. #21
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    I agree, so many times I have found that the earth leakage is tripping due to BURNING WIRES inside of a light fitting or connection box. Removing the light circuit from the earth leakage does not resolve the problem, it exacerbates it.

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    Bronze Member Brett Nortje's Avatar
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    Quote Originally Posted by Leecatt View Post
    I agree, so many times I have found that the earth leakage is tripping due to BURNING WIRES inside of a light fitting or connection box. Removing the light circuit from the earth leakage does not resolve the problem, it exacerbates it.
    The only reason those wires are burning is because there is 'too much heat per capita,' or, not enough area for electrons. think, now, if you were to have heat 'enveloping an area,' the more area there is, the more the heat spreads - like a hot spring where there is much more heat than a kettle, yet, there is so much less steam, yes?

    If you really know your stuff, you might want to make fancy wires! these wires could be made out of something denser, or, a better conductor. you could make money with the people that take care of their stuff, but builders will always use the cheapest stuff.
    !! Going to my destruction !!

  3. #23
    Diamond Member AndyD's Avatar
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    Most of the burning connections or terminations I come across are plain old poor installation techniques. It's little things like not using end ferrules on fine stranded wires when terminating, incorrectly sized connector blocks, too many wires in a termination, wires that are twisted too tight and they don't spread in the MCB cage clamp, even wires that have completely missed the cage clamp on MCB's and were just trapped behind it. Poor crimping technique on lugs is another....... the number of times I see lugs crimped using a pair of side cutters or hammer and screwdriver, I swear there must be a nationwide shortage of indent crimpers, oh yeah and over-tightened screws in plugs is another.

    Poor installation technique still remains the most common cause of burning or arcing problems I come across but poor quality manufacturing is more recently becoming a serious contender for the title. Neutral bars with only a single screw per termination are quite common to see failures on, in the good old days where there were double screwed connections failures were pretty rare. Poor clamp terminals on MCB's are more common nowadays as well, I've come across a few MCB's in the last year or two where no matter how the wire is inserted it doesn't get firmly clamped by the termination, either that or the screws strip....and before someone suggests it, yes I do use a calibrated torque driver for wiring up panels.
    Last edited by AndyD; 13-Dec-15 at 12:51 AM. Reason: spelling
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    Diamond Member Justloadit's Avatar
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    The screws strip or the thread strips because they have reduced the thickness of the termination material, so that they can save a few cents. Thinner material means there is less area to cut the thread on.

    Another issue I have found, especially with high current terminations, and areas in which there are high swings in temperature, is that the terminal screw unloosens, or more likely is that the copper in time with the high current flow, changes shape, aggravated by the pressure of the screw force on the copper. Over time the electrical contact degrades, whcih cause more temperature due to contact resistance, and the copper becomes annealed, and the start of a burning point.

    Part of maintenance in panels is to check the terminations points every 6 months to ensure that they remain tight.
    Victor - Knowledge is a blessing or a curse, your current circumstances make you decide!
    Solar pumping, Solar Geyser & Solar Security lighting solutions - www.microsolve.co.za

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    Diamond Member AndyD's Avatar
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    Yep the copper settles over time but if the wire was correctly prepared it's usually minimised. It's a habit of some to use linesman's pliers to twist the wire strands tight before putting the wire into the lug or cage clamp or if there's two wires they twist both wires together tightly. This just means the wires don't settle into the shape of the clamp as it's tightened and the contact area between the clamp and the wire is a lot less..... leading to higher resistance...... leading to heat.

    Molex have a nice beginners guide to crimping, it's biased toward production line crimping but it's an interesting read and good info.
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    Diamond Member Justloadit's Avatar
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    The issue is rather the electrician in most instances. How perfectionist is he, or is he simply trying to make a quick buck.

    I love tools, and in many instances, I have tools which I may only use once or twice a year.The fact remains, that when I have used that tool, I am confident that what I have done will stand the test of time.I am a believer of doing your best at what ever I do, even if it is digging a hole in the garden. I like to get the right tool for the job.
    Victor - Knowledge is a blessing or a curse, your current circumstances make you decide!
    Solar pumping, Solar Geyser & Solar Security lighting solutions - www.microsolve.co.za

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  10. #27
    Diamond Member AndyD's Avatar
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    Tools are important especially with processes like crimping, there's no substitute for using the correct crimper for the type and size of crimp you're using. I think your first point might be even more important though, the attitude of the person doing the work invariably reflects heavily on the quality of the finished job. I also used to think shoddy workmanship was about people trying to make a 'quick buck', I'm sure that's the motivation for some of the corner cutting I encounter almost daily but over the years I've started leaning more toward thinking it's a general personality deficit and simply a lack of pride or concern.

    Maybe in the past there was an education angle as well, bad habits like old wives tales or urban myths get passed on from generation to generation. I know a few of the things I was taught by the journeymen and masters who were my mentors when I was an apprentice were not the best practices. In those days you just did what you were taught and there were very few ways to improve or verify your inherited knowledge but nowadays with the internet there's no excuse for not constantly checking and learning and keeping your knowledge accurate and up to date.
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  12. #28
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    Just a quick question, is the use of porcelain screw connectors compliant. I prefer crimped joints.

    Sent from my GT-I9100 using Tapatalk

  13. #29
    Diamond Member AndyD's Avatar
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    They're most commonly used internally in appliances like stoves, autoclaves, kilns and ovens where there's high temperatures. As far as I know there's nothing in the regs that would mean you can't use them but they wouldn't be the best or most appropriate connector for most applications.
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  15. #30
    Site Caretaker Dave A's Avatar
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    Quote Originally Posted by jkamuz View Post
    Just a quick question, is the use of porcelain screw connectors compliant. I prefer crimped joints.
    per SANS 10142-1
    It's definitely not compliant with SANS 10142-1 for earth connections (a joint must require a tool to disconnect). When it comes to phase and neutral conductors, it is cable type dependant as I recall.

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