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Thread: where is the line?

  1. #1
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    where is the line?

    where is the line you draw between work and common sense?

    i got thinking yesterday when i was requested to verify a certificate of compliance and determine if it was an electrical installtion issue or a buyer seller issue.

    while doing this and identifying issues with the electrical installation...there was an 18 month old little boy running around the garden ans it got me thinking.
    this property has just been sold and the electrical inpesctor has been to test and the repairs apprently have been done...but unfortunalty there are number of things noted during a visual inpsection which are not correct so i have requested a copy of the COC so that i can carry out a full investigation on the buyer behalf.

    i for one am guilty of this practise because it is an easy...cheap solutions.

    removing the circuit from the electrical installtion and plugging it into the socket outlet...so that the illegal installtion is no longer part of the electrical installtion and is not covered by the regulations.

    why i took note of this was because the wires fed from the pool to the garden lights are illegal...wired in twin flex (speaker wire) no earth...exposed where they are connected because the tape has come off ...and here is this little fella running around the garden playing and i am more concerned about a pool net for the pool...yet the wires in the garden are just as dangerous if not more than not having a pool net...

    but because the lights are not covered by the COC legally there would be no claim against the inspector...but the home owner who has a COC might not be aware of the danger...because the wires are hidden in the bush and he has just moved in and thinks his house id safe because there is a COC for the electrical installation...the more i think of the electrical COC the more i believe there should be a lot more thought put into the regulations regarding domestic installations and commercial buildings especially shopping centres.

    and especially the plugging in of electrical components...like lights...gate installations...pools...i belive if the component is secured to the wall in anyway it should become part of and including in the regulations even if it is plugged in.

    the regulations are more concerned about a double pole isolator for a ceiling fan than more important issues like illegal wiring simple plugged in

    the powers that be should be more concerned about creating regulation for south africa and our typical installations than just copying the UK regulations

  2. #2
    Site Caretaker Dave A's Avatar
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    Make damn sure the plug points are on earth leakage, and the unit is working properly.

    The problem as I see it is you have to draw the line at the law - especially when it comes to COCs at property sales time. Of course there is nothing wrong with making additional recommendations - unfortunately whether to impliment them or not is at the discretion of the client. And when the client is the seller... let's just say that safety and best practice is not at the top of the priority list - at least not for the place they're selling.

    Of course they're absolutely fascinated with best practice and safety for the place they're buying.

    We've had this debate within the company ever since we went into the electrical contracting game. The closest I've come to a solution is to try to lobby for change of the law when it's needed (not requiring earth leakage units on old, unaltered installations was a prime example of something that desperately needed changing) and to do our best to educate the consumer to make responsible decisions.
    Quote Originally Posted by murdock View Post
    i belive if the component is secured to the wall in anyway it should become part of and including in the regulations even if it is plugged in.
    That's pretty close to a blanket "any fixture is part of the electrical installation" rule. I can see problems - think of geysers, stoves, airconditioning units...
    Last edited by Dave A; 05-Dec-10 at 09:52 AM.
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  3. #3
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    and if it is wired without an earth and it is not double insulated...and has exposed wires how will earth leakage help?

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    Diamond Member AndyD's Avatar
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    An earth leakage will detect a fault current of 30mA even if there's no earth connected to the appliance. The fault current causes an imbalance between the current on the live and the current on the neutral, if there's 30mA flowing through the poor soul using the appliance they there will be a 30 mA difference between the live and neutral currents. The E/Leakage breaker will detect this and trip.
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    Diamond Member adrianh's Avatar
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    A couple of questions:

    Why are pool lighting transformers isolation transformers but general outdoor cabling doesn't require isolation transformers to be used?

    Is it because a person is more likely to be shocked in a pool because the cables are more likely to be exposed to water and that the swimmer is fully grounded?

    What about rain & garden lighting?
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    and if they grab both wires one in each hand?

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    Diamond Member AndyD's Avatar
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    Quote Originally Posted by adrianh View Post
    A couple of questions:

    Why are pool lighting transformers isolation transformers but general outdoor cabling doesn't require isolation transformers to be used?

    Is it because a person is more likely to be shocked in a pool because the cables are more likely to be exposed to water and that the swimmer is fully grounded?

    What about rain & garden lighting?
    With pool lighting it's considered that a swimming pool is a high hazard zone. The transformer for pool lighting must be constructed with a galvanically isolated secondary winding to reduce the chances of it ever becoming live at the primary voltage even if the there's a fault and the chassis (laminations) of the transformer are at 220v. Garden lighting doesn't fall under this high risk zone category so a standard transformer is fine. In fact generally, garden lighting doesn't require RCD (earth leakage) protection so a fault current of 10-15Amps would be required before it trips. If the garden lighting is low voltage then the transformer must have a fused secondary which should blow if there's a fault on the secondary side. This isn't to protect people from shocks, it's to prevent fires being cause by the 12v wiring being overloaded. The light fittings themselves should be waterproof to prevent rain ingress.

    Quote Originally Posted by murdock View Post
    and if they grab both wires one in each hand?
    Then apart from them being idiots the E/leakage will still trip. The live wire goes positive and negative with respect to the neutral, the neutral should always be at zero volts no matter the load. The idiot grabbing the wires would cause an earth fault meaning electrons travel through him into and out of the live wire, these electrons(the fault current) would create an imbalance between the current flowing on the live and the current flowing on the neutral. If the actual number of electrons traveling through the idiot exceeds 187245300000000000 / second then the earth leakage trips.
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    Diamond Member Justloadit's Avatar
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    Quote Originally Posted by AndyD View Post
    Then apart from them being idiots the E/leakage will still trip. The live wire goes positive and negative with respect to the neutral, the neutral should always be at zero volts no matter the load. The idiot grabbing the wires would cause an earth fault meaning electrons travel through him into and out of the live wire, these electrons(the fault current) would create an imbalance between the current flowing on the live and the current flowing on the neutral. If the actual number of electrons traveling through the idiot exceeds 187245300000000000 / second then the earth leakage trips.
    Not quite as you say, you are assuming that the person is barefoot and some part of his body is touching earth. What if he is wearing rubber shoes, and no part of his body touches earth, and he holds each wire individually in each hand, he will then be electrocuted and the earth leakage will not see this as a fault but something closing the circuit, just like a lamp.

    The manner which the earth leakage operates, is that it looks for an imbalance of up to 30mAmp between the live and neutral wire. The difference in current between the Live and Neutral, is then assumed that is flowing into earth, and then the earth leakage trips.

    The way in which the earth leakage works, is that the live and neutral wires are fed in a transformer toroidal core. The sine wave flowing in the live wire cancels the sine wave flowing out the neutral wire when any load is connected to the system. when an earth fault occurs, the current in the neutral wire is less than the current in the live wire, so there is no canceling effect, and the difference in the current is detected in the core. This is amplified, and a reference is used to measure this leakage current, if it exceeds 30mAmps it trips the circuit breaker.
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    Diamond Member AndyD's Avatar
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    Quote Originally Posted by Justloadit View Post
    Not quite as you say, you are assuming that the person is barefoot and some part of his body is touching earth. What if he is wearing rubber shoes, and no part of his body touches earth, and he holds each wire individually in each hand, he will then be electrocuted and the earth leakage will not see this as a fault but something closing the circuit, just like a lamp.
    Not necessarily barefoot, normal footwear will usually pass 30mA @ 220v unless it's bone dry.
    You're right though, if the idiot is standing on an insulated mat or wearing neoprene Doc Martens then there will be no fault current and the earth leakage will just see him as a load and not trip. If he holds one wire in each hand with suitably moistened fingers then the current that flows through his body would be more than sufficient to defibrillate him and send him into cardiac arrhythmia.
    The standing on a rubber mat scenario is a similar problem to circuits with high Zs which develop insulation problems and aren't effectively protected by RCD's. This is common with TT earthing systems where fault currents may not reach the 30mA tripping threshold.
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    Diamond Member adrianh's Avatar
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    But isn't that exactly why there should be a secondary side breaker besides the earth leakage?
    How easily someone is offended is directly proportional to how stupid they are.
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