[Question] Plastic switch covers.

[Henthel]

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?

[GCE]

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

[GCE]

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.

[Dave A]

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.

[SeanM]

Morning All

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

[Henthel]

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.

[GCE]

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.

[Henthel]

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.

[SeanM]

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.

[Leecatt]

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

[GCE]

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

[Dave A]

...
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.

[AndyD]

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.

[Henthel]

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.

[Henthel]

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.