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Thread: Plastic switch covers.

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    Plastic switch covers.

    If an electrical installation has no earth wire to light switches and the conduit in older installations do not provide an efficient earth, is it accepted legal practice to have plastic switch covers with plastic screws, thus insulating the switch and receptacle from human contact?

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    There was a time period around 2001 that you did not need to install an earth wire to a light switch if it was PVC with pvc screws.
    It only lasted a year or two and then scrapped.

    If I was doing a COC on the installation you describe I would assume it was done within the time period that the metal conduit was used as an earth conductor and would therefore ensure that there is an earth at the light switch.
    Often you can give the locknuts a turn and get to your readings

    It is cheaper to quote the client now for separate earth and install then have a different opinion ( read AIA test) and be forced to do at your own cost later.

    We ensure that there are earth wires at each point , also maybe the reason we don't get much COC type inspection work.
    I prefer protecting my licence then end up in arguments

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    Making me put my searching cap on -


    6.12.3.1 The following conductive parts shall be earthed:
    a) all exposed conductive parts of an installation other than those described
    in 6.12.3.2;
    NOTE Metal enclosures on PVC conduit should be earthed if they can become
    live and can be touched.
    b) all conductive cable sheaths and armouring, wireways and catenary
    wires;
    c) the earthing terminal of a socket-outlet;
    d) the secondary winding of a transformer if it is not a safety transformer;
    e) earthing terminals of all permanently connected electrical equipment and
    appliances;

    f) conductive parts of discharge luminaires and equipment that need special
    earthing arrangements; and
    g) all class I equipment.
    6.12.3.2 The


    e may not apply to all switches but some do have earthing terminals which will mean an earth wire

    6.1.9 The continuity of neutral and earth circuits shall be ensured at all
    times, and, except where the luminaire is used as a wireway for throughwiring,
    the continuity shall not be disturbed during repair, replacement or
    removal of any appliance.


    8.6.3 Resistance of earth continuity conductor
    Use a resistance meter to measure the resistance of the earth continuity
    conductors between the consumer's earth terminal and the earthing
    terminals of all points of consumption and switches. The values shall not
    exceed those given in table 8.1


    The above tend to indicate that you need an earth but a bit grey - Seem to distinctly remember something being brought in that every switch point will have an earth , looks like I could be wrong.

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    I've understood the situation to be exposed conductive parts need to earthed, and that if the component has a earthing terminal, it must be connected to earth (some small print, particularly relating to safety supplies applies).

    It had me looking at light switch chassis, and the metal ones in my store have an earth terminal. The plastic chassis switches (unsurprisingly) do not.
    The trouble with opportunity is it normally comes dressed up as work.

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    Morning All

    Please remember that it is illegal to use the metal Conduit as an earth.

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    Thank you all for your input. SeanM raises an interesting point that is another area shaded in grey. Many old installations made use of the well installed steel conduit (in the day of artisans) before an earth conductor became compulsory. In many houses and blocks of flats, you will find this. The way I read the Regulations, this is acceptable on installations completed before 2008, with the proviso that acceptable earth continuity readings are obtained during tests. This also raises another problem when it comes to replacing a socket outlet. The new plastic outlets have no continuity from the earth terminal to the mounting plate. You must thus install a flying earth lead that is lugged and properly secured to the wall box to ensure a proper earth. Your valuable comments will be appreciated.

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    Hi

    I pulled out the oldest regulations that I have which is SABS 0142-1 valid from date of approval 1 November 2001 .
    In that edition 6.12.1.3 already stated that a wireway may not be used as an earth conductor.
    I cant find an older edition - I think that is more a prior to 1994 than 2008 with regards to a separate earth.
    I have a feeling that when I wrote reg's in 1988 a separate earth was already a requirement - I don't ever remember using conduit as an earth.
    Yes if the building is old and the conduit is still the screw type the chances are that the regulation at time of installation allowed the conduit to be an earth and if your readings are acceptable you could sign off.
    We did put in flyleads from the steel box to the earth terminal in old installations , generally factories where the conduit is still good.
    We have had a couple of old houses where the conduit has rusted through under the ground and had no earth , back in the day when I would tackle that sort of work.
    Now I refuse to sign off without installing earth wires.

    I have had conversations with AIA's where they read the reg's as saying if work has been done on a circuit then the complete circuit should be upgraded to the new regulations.The definition of electrical installation work includes repairs and maintenance.

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    Thank you GCE, I firstly want to ensure you that I am not trying to find loopholes in the system. I just want to confirm what the inspection authorities class as "reasonably safe" in a fairly old installation. In the ECB test report attached to the CoC, page 4 point 13 allows a choice of (a) or (b) in the answer and point (b)reads, and I quote: - In the case of installations that existed before the publication of this edition of SANS 10142-1, the installation complies with the general safety requirements in this part of SANS 10142-1 and is reasonably safe. - This statement forms part of the test report and my interpretation is that if your test results comply, the installation is reasonably safe. I can not see how a person can charge a customer for a complete rewire, if the earthing is within the required parameters. That is also what prompted my initial question regarding switches. Surely a plastic switch with a plastic cover and no exposed metal parts is "reasonably safe". The previous edition of SANS 10149-1 to my knowledge was published in 2008-2009. Please correct me if I am wrong on this point.

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    Hi Henthal

    With regards to your question on a plastic light switch this is safe.

    Take the plastic LED down light unit no earth required.

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    The answer is quite straightforward when you look at the whole of SANS 10142.
    First of all at the beginning of SANS 10142

    1.2.Aspects covered by this part of SANS10142.
    This part of SANS 10142 covers
    I) replacement or maintenance of components


    From this short sentence it is clear that any replacement or maintenance of any component of the electrical installation must be done under the current version of SANS 10142

    According to the latest version of SANS10142:
    6.12.1.3 A wireway shall not be used as an earth continuity conductor
    Last edited by Leecatt; 03-Feb-19 at 06:32 AM. Reason: Adjustments of paragraghs
    To make a mistake is human, to learn from that mistake is knowledge and knowledge is strength.

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