T&E Two way switching

[omph]

So, I was at a client's house today, and was investigating some other issue only to discover that some sparky many moons ago decided to use a 2 core + earth for a 2 way switch. The earth was switched live, no sheathing, and he barely had any tape to cover it, and right next to the bare switched earth were some coiled earth cables - what an idiot.
Has anyone seen t&e used like this before (minus the lack of sheathing) ? I've seen it a few times now and am wondering whether this may have been a thing a few decades ago - doubt it, but would be interesting if anyone has any stories to tell.

 

[CBW]

I’ve seen a thermostat wired up with the earth being used as the switch live, only time I’ve seen it though. (I’m not an electrician).

 

[Taylortwocities]

Seen it several times in lighting, and many times in heating systems.

It has never been a “thing”. Only done by people who don’t know what the regs are. Often DIYers who run twin&earth from an existing switch to add a second switch, and finding, after plastering the wall chases, that they are missing a conductor!

A few decades ago the regs were the same on the point of the unsleeved cpc not to be used as a live conductor. Early pvc cables used for lighting - when an earth was not a regulation- included 3-core (and no earth) cable in national red, white and blue.

 

[bernardgreen]

The worst I heard about was the CPC used as a live conductor to a terminal in a switch and then a link from the switch terminal to the Earth terminal in the back box

 

[markyd1]

Yep...cpc used as a switch line for a fan...no sleeving at either end

 

[opps]

I have seen the earth used as a permenant live on extractor fans with an over overrun.

 

[omph]

Correction: the CPC is perm live . Turns out it was some shady builders tinkering on the cheap.

So the owner is a little peed as you'd expect, but fixing it properly is not possible since they've blown a load on renovations and can't bare to deal with any more significant work to correct it.

Since they want to move to metal plated switches, I am going to re-earth the CPC, and pull a (fortunately) live feed from the switch next to it, which will effectively move it onto the other lighting circuit - such a PITA.

What solutions did you guys adopt to fix the issue when encountered ?

 

[CBW]

What solutions did you guys adopt to fix the issue when encountered ?

Sorry to say, mine was exceptionally easy, disconnected at room stat, disconnected boiler end and renewed with wireless room stat.

 

[EFLImpudence]

and pull a (fortunately) live feed from the switch next to it, which will effectively move it onto the other lighting circuit -

That sounds like it will result in what is known as a "borrowed neutral" - i.e. the neutral from the light is on another circuit - not advisable.

It will trip both RCDs if the circuits are on different RCDs.

 

[bernardgreen]

and pull a (fortunately) live feed from the switch next to it, which will effectively move it onto the other lighting circuit - such a PITA.

Are both light circuits fed from the same RCD ?

If not then the Live to the lights is coming from one RCD and the Neutral for the lights is coming from another RCD.

That will mean the RCDs will both trip when the lights are switched ON

EDIT Too slow EFL got there first

 

[SUNRAY]

Sadly I've seen this system several times, one of the first had been very carefully trimmed inside the sheath to allow yellow sleeve (I assume removed from 3C & E) to be slipped inside to make it look like 3C without earth with red, yellow, black colours. The yellow and black even had red marker sleeves added to make it look totally pukka.
Others have not been so well done, all to often the only sleeveing available is green/yellow and there's usually exposed copper twix sheath and sleeve.

 

[omph]

@EFLImpudence, @bernardgreen - This is a very old install with no RCDs, so tripping is not an issue. I will do some remedial work to keep them both on the same circuit in the event they update their gear.
I would have imagined that gutting the house would have allowed for them to rewire and upgrade the CU but apparently not. Although considering the prices these days I'm not surprised either.

 

[EFLImpudence]

Ok, but it is potentially dangerous - although often done.

Depending on which you think the lesser of two evils, you could put both light circuits on the one MCB.

 

[xm77]

Yup seen it as per the above on timer run-on bathroom and kitchen fans where the CPC earth is used as the switched live.
This was on a house all wired up by professional electricians as a new build in 1990.
At least the bare cpc was wrapped in red insulation tape at the terminations........

What did they do on two way switching lighting circuits you may ask?
Wire it up in T&E plus a separate running single is the answer.

 

[Taylortwocities]

What did they do on two way switching lighting circuits you may ask?
Wire it up in T&E plus a separate running single is the answer.

The single is (I hope) single plus earth?
Were the electricians from Rooster Cogburn Ltd??
PS back in the past, two way was wired like this.