Unconventional light wiring

zmrfgz · Oct 10, 2019

I'm removing all the lighting in my home (will get an electrician to fit the new lights) and came across this wiring configuration. The switch in the pic was a part of the light fitting, and the earth tab was connected to the light housing. There is only one wall switch. Every other light in the house was wired normally, that is just connected to a single (or sometimes two daisy chained) L/N/E wire. What's going on here?

[ElectriciansForums.net] Unconventional light wiring

multimick · Oct 10, 2019

bet your sparks will be overjoyed that you have done all this,however the circuit is perfectly normal, but a mess.

Lucien Nunes · Oct 10, 2019

It's a bit odd. The cable with the green sleeved earth looks like the supply, except that the line (red) was not connected and was replaced by whatever that smaller white cable is with its sheath going right into the terminal. That does not look from here like a normal installation cable, so my first guess is that it is a DIY workaround for the line in the real supply cable having been damaged. The cable may or may not be suitable for the purpose.

Then it looks normal, with the switch cable being the one connected with its black to the red of the light fitting. However, its CPC does not appear to be connected, so the switch may not have an earth.

I would think the electrician who installs the new lights will want to investigate the reason for the separate line conductor entering the fitting as it could indicate an inappropriate repair.

zmrfgz · Oct 10, 2019

Thanks. The switch was earthed when it was originally connected to the light's housing, along with the green earth wire. If the real supply cable was damaged, then why would there be two more cables running to repair it?

Dustydazzler · Oct 10, 2019

you have a switched feed and neutral to the buld holder via an inline switch to boot

then a blanked off live and a what appears to be some flex feeding the light

looks a bit rough if you ask me

Lucien Nunes · Oct 10, 2019

I meant the switch on the wall may not have an earth as the CPC in its cable was not connected this end.

HappyHippyDad · Oct 10, 2019

Its a little difficult to work out from the picture what is going on but it looks pretty normal.
2 PL's, 1 x N and 1 x SL, plus an extra little switch. I cant quite make out what the white flex is doing.

Zerax · Oct 10, 2019

I bet that's an extension from the original pendant position... and they just used whatever they had to make it work..

Dustydazzler · Oct 10, 2019

Zerax said:
I bet that's an extension from the original pendant position... and they just used whatever they had to make it work..

them there rough old builders...

ElectroChem · Oct 10, 2019

The white cable is most likely an SDI (Single core Double Insulated), often used in Australia to carry an extra active conductor.

My thoughts on how this setup came to be:
1. TPS bringing N+E from the nearest light on the circuit, active will either be switched with the other light or not connected, depending on if this light is new or was on the other circuit already. The earth is not sheathed, it's green-yellow insulated.
2. SDI bringing a hard active then twin-active TPS (red-black, more modern Aussie twin-active will be red-white) to a switch. Light switches do not have to include an earth here unless it's a metal faceplate, most household gear is plastic fronted.
3. Estimate 70s-80s, after we moved to insulated earths but before stranded cable became more common at the 1.5mm2 range.

zmrfgz · Oct 11, 2019

Yes, the wall switch is not grounded, but none of them are due to being plastic.

Yes, found another light nearby with a daisy chained TPS, presume that's providing the N+E.

Found a nearby light switch that provides the SDI active (but doesn't switch it).

The two core cable goes back to a switch that looks a little different to the others, so maybe it was an afterthought (as opposed to bypassing cable damage).

House was built early 80s.

Thanks guys, all makes sense now.

Kidsolo · Oct 20, 2019

Looks like there was no active where they got the neutral and earth from, so they had to run a SDI active from another outlet. The red wire in the connector should be dead.

Unconventional light wiring

zmrfgz

multimick

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Lucien Nunes

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zmrfgz

Dustydazzler

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Lucien Nunes

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HappyHippyDad

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Zerax

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Dustydazzler

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ElectroChem

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zmrfgz

Kidsolo

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