What constitues an alteration to an existing installation.

**Leecatt** · 03-Jul-12, 11:05 AM

aGAIN

Originally posted by Leecatt

Here is the scenario: you climb in the roof and it is wired in pvc cleated wiring running into metal downpipes.
The older installation has earth wires attached to the exposed portion of the metal downpipes, in the roof.
On the older installation there are no earth wires running down into the pipes, to the light switches or plugs.

There have been some additional plugs and lights and they have been wired using pvc pipe and pvc wires which are tapped of the older installation.
The new additions have all got the required earthing which is also tapped of the older installation

SANS says "If an existing
installation is extended or altered, such extension or alteration has to comply
with the provisions of this part of SANS 10142 that were applicable at the
time of the erection of the extension or alteration."

I take this to mean that only the new portion of the circuit has to comply with the latest regs.

In a recent statement in the media it was said that "changing a plug socket or light switch does not constitute an alteration therefore you must not upgrade the older installation when changing a plug socket or light switch."

In my given example if you change a plugsocket or light switch then you must upgrade the effected circuit to the latest regs because the new sockets and light switches have different requirements to the older ones. For example the new plugs need an earth wire connection, and connecting a wire from the earthing terminal to a screw on the metal housing is "using the pipework as an earth continuity path" which is no longer legal.

Another thing is, by installing the new plugs an earth leakage now has to be added to the circuit. After that is done EVERY plug has to have an earth wire as required by the earth leakage.

Comments?

does anyone have an opinion on this, i am trying to get a debate around this to see if I am wrong

**Dave A** · 03-Jul-12, 07:59 PM

My thought is if you're replacing a plug point on an old installation, there usually is an existing earthing point to use.

**AndyD** · 04-Jul-12, 12:57 AM

I didn't take a stab at this cause I didn't understand the question fully.

Which parts of the socket circuit are the original 2-wires in steel conduit and which parts are PVC conduit with housewire or FT&E?

Am I along the right lines with this setup?

**dfsa** · 04-Jul-12, 02:46 AM

You have come across an original installation before earth leakage time. At the time it was purely a 2 wire system and the actual earth was used for neutral. That was also at the time where open wires was used in the roof. You should find that the old section have the wires a couple centimeters apart and fixed onto insulators. Around 30 Years ago the law changed where plugs and appliances needed to be run through an eart leakage, to prevent people from getting shocked if there are a leakage from any metal surface.

When the extensions was done on the installation you found, the original part of the installation was supposed to be upgraded to all run via the earth leakage and extra earthing to all points was supposed to have been installed.

If you replace an older plug socket ( You will find it is actually bakelite) to a new one, you need to pull the needed earth from the socket to the nearest earth point. Even with today's new plastic socket covers, you still need the earthing, because people might still plug a 3 wire appliance into the socket and then will need the earthing for leakage protection.

**Leecatt** · 04-Jul-12, 07:51 AM

Originally posted by AndyD

I didn't take a stab at this cause I didn't understand the question fully.

Which parts of the socket circuit are the original 2-wires in steel conduit and which parts are PVC conduit with housewire or FT&E?

Am I along the right lines with this setup?

[ATTACH=CONFIG]2680[/ATTACH]

Almost. there are no cables involved. This is an old installation. The original socket circuit was wired as such: two pvc wires, red and black, exiting the Db board conjute metal piping, mounted upon cleats and running through the roof. Every so often there is a joint, with another 2 wires, and those 2 wires run away from the cleated wires and into a metal conjute down to a plug. The lighting circuit is similar. All the metal conjute pipes are bonded at the exposed part in the roof, to a earth wire and then usually to the water pipes. The earth wire does not travel down the pipe with the red and black wire.
The question is, when the socket outlet is replaced, does there have to be an earth wire delivered down the conjute pipe to the new socket outlet (i support this theory) or are you allowed to drill a screw into the metal box and attach a wire from the plug socket to the screw. (I do not support this theory)
Disregard the extensions for now that was actually for another question

**AndyD** · 04-Jul-12, 10:38 AM

Originally posted by dfsa

You have come across an original installation before earth leakage time. At the time it was purely a 2 wire system and the actual earth was used for neutral.

This sounds like a TN-C system. I've never seen one . An earth leakage breaker (RCD) is unlikely to operate effectively on this system. Single pole disconnects only should be used. I would consider any TN-C system as hazardous and would rewire as TN-C-S and PME the installation.

**murdock** · 04-Jul-12, 12:00 PM

ir depends on who is doing the job...if a handy man is doing it...just take off and replace...if an "electrician" is doing the job...he would replace the plug and put a screw or pop rivet into the steel frame...then carry out a loop impedance test or an earth continuity test...(i would prefer the loop impedance test)...if within the required limits...it is ok...if not then you need to get and earth from a reliable source...back to the db...bonding strap around the pipe in the roof...geyser earth etc etc.

**Leecatt** · 05-Jul-12, 08:09 AM

Originally posted by murdock

ir depends on who is doing the job...if a handy man is doing it...just take off and replace...if an "electrician" is doing the job...he would replace the plug and put a screw or pop rivet into the steel frame...then carry out a loop impedance test or an earth continuity test...(i would prefer the loop impedance test)...if within the required limits...it is ok...if not then you need to get and earth from a reliable source...back to the db...bonding strap around the pipe in the roof...geyser earth etc etc.

In my opinion, putting a screw or pop rivet into the steel frame would constitute a violation of 6.12.1.3 'A wireway shall not be used as an earth continuity conductor'.
What do you think?

**AndyD** · 05-Jul-12, 10:58 AM

Depends if you're using the actual wireway as the earth or you're just earth bonding the wireway as an extraneous item. In my sketch above the backbox and steel conduit in the wall are bonded, they're not used to actually carry the earth.

**murdock** · 05-Jul-12, 11:09 AM

Originally posted by Leecatt

In my opinion, putting a screw or pop rivet into the steel frame would constitute a violation of 6.12.1.3 'A wireway shall not be used as an earth continuity conductor'.
What do you think?

then lets look at how most installation worked in the past...as mentioned in another thread work...the steel frame of the socket outlet (crabtree and the old lumex plugs are a good examples) were screwed to the 4x4 /4x2 flush box which was passed for many years...i have noticed on some of the new installations the engineer has insisted that a link be put in between the 4x4/4x2 flush metal box and the frame of the socket outlet

most old domestic installations used the conduit and 4x4 or 4x2 steel box as the earth...ie when you removed the plug it was no longer earthed...just one example...in a situation like this i have come across a fair amount of so called elctricians (if they have ntc 3 they regard themselves as electricans...ntc 6 master elctricians) who remove the old metal framed socket and replace it with the new plastic sockets...becuas emost of them only own a couple of screwdrivers and a pair of pliers they cant test the plug to check for earth...the fact that there is no earth wire to connect to the socket just means that it doesnt need one...yeah i know you ar eshaking your head...what is really scary is when you confront the owner of the company who sent out the bright spark to replace the socket...says no problem just pull in an earth wire and send me the bill...i take out my plug tester and find they have replaced 14 socket outlets in the duplex...not one has an earth...i pack up my tools and advise the customer to contact the company who replaced the plugs.

**murdock** · 05-Jul-12, 11:19 AM

Originally posted by AndyD

Depends if you're using the actual wireway as the earth or you're just earth bonding the wireway as an extraneous item. In my sketch above the backbox and steel conduit in the wall are bonded, they're not used to actually carry the earth.

the older installations used the piping and metal boxes as the earth...there were only 2 wires in the electrical installation...red and black...no earth...the piping above the db would be bonded with a bonding strap and water pipes etc...including the electrical piping and earth wire from the overhead supply cable...all connected to one point...the problem however...over the years the pipes in coastal areas have rusted creating a higher resistance...deeming the earthing inadequate...so back to connecting an earth wire from the plastic socket or even replacing the metal one with another metal one...personally i would run a new earth wire back to a point were i can connect in to the incoming earth wire...be it an overhead line wher ethe earth wire would be running across the roof sapce or to the DB in the case of an underground armoured cable treminated at the DB

**Leecatt** · 05-Jul-12, 11:31 AM

Originally posted by AndyD

Depends if you're using the actual wireway as the earth or you're just earth bonding the wireway as an extraneous item. In my sketch above the backbox and steel conduit in the wall are bonded, they're not used to actually carry the earth.

Thanks for your reply Andy, I really do appreciate the input on this subject.
However in this case that Murdoch mentioned the cojute pipe is being used to connect the earth pin of the socket outlet to the earth wire bonded to the top of the same conjute.
My stance however, is that I feel that the replacement of a socket outlet, or light switch, DOES constitute an alteration to an existing installation, and therefore new rules have to be applied to the existing installation. I have heard voices from well qualified sources deny this.

**Leecatt** · 06-Jul-12, 12:40 PM

Originally posted by murdock

the older installations used the piping and metal boxes as the earth...there were only 2 wires in the electrical installation...red and black...no earth...the piping above the db would be bonded with a bonding strap and water pipes etc...including the electrical piping and earth wire from the overhead supply cable...all connected to one point...the problem however...over the years the pipes in coastal areas have rusted creating a higher resistance...deeming the earthing inadequate...so back to connecting an earth wire from the plastic socket or even replacing the metal one with another metal one...personally i would run a new earth wire back to a point were i can connect in to the incoming earth wire...be it an overhead line wher ethe earth wire would be running across the roof sapce or to the DB in the case of an underground armoured cable treminated at the DB

I never took coastal conditions into account as I am inland , but a very valid point.