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Thread: Plastic switch covers.

  1. #11
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    Hi

    This thread has made me do some serious thinking.
    We need to remember that the OHSA also has a play on the regulations and the way we conduct our business .

    My understanding of reasonable safe is that it must comply to section 5 , fundamentals , of the code .
    So metal conduit on an old installation and now fitted with PVC switches would not need to have an earth wire as I read it .

    But as pointed out by Leecatt above any replacement etc must comply to the latest version at the time.Pvc switches where not available at the time of metal conduit and it is therefore assumed that it was done much later. ( the majority of PVC switches came out after the change in reg's that stated earth wire must go to the earthing terminals of all permanently connected electrical equipment and appliances. My memory anyway)

    If I look at the latest regulations I cannot come up with a reason to run an earth wire to a light switch that is PVC without an earth terminal , has pvc conduit and pvc wall box.
    But - If I look at the OHSA , electrical machinery regulations , section 18 Earthing

    Earthing
    18. ( 1) An employer or user shall cause -
    (b) all accessible metallic parts of electrical machinery that, though normally
    not forming part of an electrical circuit, may become live accidentally, to be
    protected by an insulating covering or to be otherwise enclosed or to be
    earthed and the resistance of the earth continuity path shall not exceed
    0,2 ohm, except-
    (iv) metalwork of fixed electrical machinery where such metalwork is
    more than 2.4 m above the floor: Provided that this exception shall
    not apply where such metalwork is situated in any position likely to
    become damp, or in an elevator shaft, or near rotating machinery,
    or in contact with a wall, ceiling or other support constructed of or
    covered with conducting material


    To me , and maybe I am taking it out of context , I need to earth the metal box/ conduit as it is in contact with the wall , and to bring it into context the conduit may be above 2,4m - On an old installation I suppose that means that it must be earth but not necessarily have an earth wire.

    In answer to Henthel's question "I can not see how a person can charge a customer for a complete rewire, if the earthing is within the required parameters" The introduction of SANS 10142 and the OHSA gives me a chance to insist on more than the basic requirements .I have pasted 5 pieces below which to me would be relevant when trying to persuade the client to accept my insistence on installing separate earth wires.I know that there is a chance of a hot connection which may cause a smoldering of the switch hidden behind a curtain that sets the fire off or the wiring burning back in the conduit and not tripping the supply until the roof space starts smoldering.
    May sound extreme but I watched my folks lose there entire house and contents in the space of 30 minutes due to a short on an electric blanket while they were in the room.Made me rethink on what is required by regulation and what is required from me as a responsible person signing off reasonable safe.

    As a responsible person signing the COC I need to be 100% sure in myself that what I am declaring as reasonable safe is definitely so .There can be no doubt within myself otherwise I will not be able to convince somebody else in the event of a problem that I did everything possible to prevent a problem.If that doubt is there I then run the risk of being prosecuted under the OHSA.

    Think it a reason that I don't do COC type work on existing installations as we just quote on the work , to do it as we see correctly , only to go back later to see the disaster. If we do COC type inspections we will only do for the buyer as he understands whereas the seller wants as cheap as possible.


    Extracts from SANS 10142-1
    Compliance with this document cannot confer immunity from legal
    obligations


    The aim of this part of SANS 10142 is to ensure that people, animals and
    property are protected from hazards that can arise from the operation of an
    electrical installation under both normal and fault conditions. An electrical
    installation has to provide protection against:
    – shock current,
    – overcurrent,
    – fault current,
    – overvoltage,
    – undervoltage,
    – excessive temperatures, and
    – electric arcs.


    This part of SANS 10142 is concerned with ensuring the basic safety of
    electrical installations. To ensure the protection of people, animals and
    property and the proper functioning of an installation, the designer of an
    electrical installation should be aware of:
    a) the characteristics of the power supply,
    b) the nature of the demand, and
    c) the operating environment of each part of the installation


    Extract From General Administrative regulations
    9. General duties of employers and self-employed persons to persons other than their employees

    (1) Every employer shall conduct his undertaking in such a manner as to ensure, as far as is reasonably practicable, that persons other than those in his employment who may be directly affected by his activities are not thereby exposed to hazards to their health or safety.

    (2) Every self-employed person shall conduct his undertaking in such a manner as to ensure, as far as is reasonably practicable, that he and other persons who may be directly affected by his activities are not thereby exposed to hazards to their health or safety.


    Extract from General Safety Regulations
    2. (1) Subject to the provisions of paragraphs (f), (g), (h) and (i) of regulation 5 of the General Administrative Regulations published under Government Notice R. 2206 of 5 October 1984, every employer and every user of machinery shall make an evaluation of the risk attached to any condition or situation which may arise from the activities of such employer or user, as the case may be, and to which persons at a workplace or in the course of their employment or in connection with the use of machinery are exposed, and he shall take such steps as may under the circumstances be necessary to make such condition or situation safe

  2. #12
    Site Caretaker Dave A's Avatar
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    Quote Originally Posted by GCE View Post
    ...
    or in contact with a wall, ceiling or other support constructed of or
    covered with conducting material[/I]

    To me , and maybe I am taking it out of context , I need to earth the metal box/ conduit as it is in contact with the wall , and to bring it into context the conduit may be above 2,4m - On an old installation I suppose that means that it must be earth but not necessarily have an earth wire.
    Remember that the wall needs to be constructed of, or covered with a conductive material. Brick and plaster, wood and plasterboard would not be conductive materials.
    Last edited by Dave A; 04-Feb-19 at 12:27 PM. Reason: fixed typo
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  3. #13
    Diamond Member AndyD's Avatar
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    Quote Originally Posted by Dave A View Post
    Remember that the wall needs to be contructed of, or covered with a conductive material. Brick and plaster, wood and plasterboard would not be conductive materials.
    Interesting discussion.

    I'd argue that brick, plaster, wood and drywall board are all conductive to some degree depending on their moisture content. Ufer earthing arrangements could be considered proof of this; Ufer (concrete encased conductors/electrodes), whilst not mentioned in SANS 10142 are recognised in othe regs sucah as IEC/SANS 62305-3. I've also seen numerous 'tingling' faults over the years where the plaster or slab has become partially conductive.
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  4. #14
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    Hi Leecatt, I refer to your post of 25 April 2016. What made you change your opinion so drastically since that time? In that specific post, you seem to agree with my present opinion.
    I have researched the origin of this practice in South Africa and the only conclusion I can come to is that prior to 1960 we were still under British rule and thus using British standards. B.S. 7671 Reg. 543.2.5 and 543.3.6 still allow for wireways to be used as CPC's (circuit protective conductors). I am certain that before South Africa became a Republic, the practice of using the conduit as an earth was widely acceptable. I started my apprenticeship with the South African Railways in 1967 and at that time it was common practice (on railway housing) to have a separate earth conductor for socket outlets. The only lights that we earthed were metal clad fittings and fluorescent fittings. Round bakelite and porcelain switches on wooden blocks were still widely used, Some even had brass covers and toggles. Interestingly, South Africa led the world pioneering Earth leakage protection devices and the Mining industry were the leaders in installing them. The first domestic units installed were FWJ units in 400 houses in the village of Stilfontein (Western Transvaal). This was in 1958. South Africa was also the first country in the world to make the installation of E/L units mandatory. We have come a long way since then.

  5. #15
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    Quote Originally Posted by Henthel View Post
    Hi Leecatt, I refer to your post of 25 April 2016. What made you change your opinion so drastically since that time? In that specific post, you seem to agree with my present opinion.
    I have researched the origin of this practice in South Africa and the only conclusion I can come to is that prior to 1960 we were still under British rule and thus using British standards. B.S. 7671 Reg. 543.2.5 and 543.3.6 still allow for wireways to be used as CPC's (circuit protective conductors). I am certain that before South Africa became a Republic, the practice of using the conduit as an earth was widely acceptable. I started my apprenticeship with the South African Railways in 1967 and at that time it was common practice (on railway housing) to have a separate earth conductor for socket outlets. The only lights that we earthed were metal clad fittings and fluorescent fittings. Round bakelite and porcelain switches on wooden blocks were still widely used, Some even had brass covers and toggles. Interestingly, South Africa led the world pioneering Earth leakage protection devices and the Mining industry were the leaders in installing them. The first domestic units installed were FWJ units in 400 houses in the village of Stilfontein (Western Transvaal). This was in 1958. South Africa was also the first country in the world to make the installation of E/L units mandatory. We have come a long way since then.
    Sorry, I posted this reply on the wrong thread.

  6. #16
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    Wow!
    Gents thank you so much for all the input. I never thought that the thread would become so interesting. I agree with GCE that if things are not clear, all possible avenues must be investigated. In a court of law, ignorance counts for nothing. The OSH Act, Mine Health and Safety Act, Building Regulations etc. must all be taken into consideration. In the end a proper risk assessment done by a team of interested parties will find whether it is an acceptable decision or not. I think in the absence of hard and fast rules, you should let your conscience guide you as well.

  7. #17
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    Hi

    The thread was thought provoking - I found it scary that there is no hard and fast rule that if you are using PVC wall boxes , pvc conduit , pvc switches and light fittings that you need an earth wire.It is the right thing to do but leaves it open to debate
    Means that light circuit's in an installation could be wired without any earth wires.

    Think there needs to be a change to the regulations and thought that maybe we need to arrange the extra wording in red below to the clause.

    Not sure if anybody agrees or thinks that it is already covered.?

    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 and points ( lights switches , light fittings, etc even if PVC ) of all permanently connected electrical equipment and appliances

  8. #18
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    GCE, the Regulation starts of quoting "conductive parts". It goes on to say "exposed" conductive parts. Also metal boxes on PVC that can become live and can be" touched" . Then - anything "out of arms reach" need not be earthed. These Regulations were written to protect the layman - user or tenant. Not for the electrician or competent person working on the installation. It must be safe for the person operating the switches daily. A person that is not competent should not even attempt to change a light bulb without switching off the main switch. For that matter, a careful electrician would do the same. It is very easy to become complacent and that is normally when accidents happen. To go overboard and try and earth plastic and PVC fittings would serve no purpose. Rather re-write the regulations to exclude an earth wire on light circuits where it will serve no purpose. It is like saying that you should have an earth on a double insulated appliance. If you have a short-circuit fault between live and neutral, your circuit breakers should provide protection and trip the supply before the house burns down. In most TN connected supplies, your neutral and earth are at the same potential anyway. That is just my humble opinion.

  9. #19
    Site Caretaker Dave A's Avatar
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    I see value in amending the standard in such a way it ensures there is an earth wire available at each electrical point, except where the absence thereof is for good reason (e.g. safety supplies).

    In the light switch point situation that is the focus here, we could talk about the challenge faced if there is no earth wire available and the client wants (or needs) to change the plastic light switch to something a bit fancier, (or robust) that has an exposed conductive material. The more common problem though is where the client wants to replace a light point plastic bowl fitting with a ceiling fan incorporating a luminaire.

    Things change. Let's make sure there is an earth available.
    The trouble with opportunity is it normally comes dressed up as work.

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