Old style earth ring and Part P inspection

[r.bob]

I understood that we were under no obligation to change existing installations to meet current regs, but wonder how the following fits in:

The council appointed inspector says that I cannot connect the earth wire from the new wiring in new en-suite (not a new circuit, just a JB from existing lighting cable) to the existing earth circuit, which is a bare 6mm ring, unsheathed. This earthing, which is only for the lighting circuit, runs in the ground floor ceiling and the loft and serves all the lighting for the home.

Instead he would like me either to run a fresh earth wire to the CU just for the en-suite (even though both en-suite fan and lights are double insulated and need no earth!) OR to use an existing 2.5mm spur to serve the lights as well, via a fused spur.

Does this sound correct?

 

[electronicsuk]

Unfortunately you are pretty much at the building inspectors mercy, and you will need to do as he asks in order to get the installation certified. In any case, if your wiring is old enough to have 2-core cable with a separate unsheathed CPC then I'd be dubious about making any alterations or additions to it whatsoever. Exactly what is the existing cable? Rubber sheathed?

 

[r.bob]

Thanks Matthew

Yes, I agree, there are so many opinions that I thought I would get the inspector to tell me what he needs, but it rankles a bit if he's asking for what isn't required!

The house was built in 1959 and has modern plastic coated cables, except that the earth wire in the T&E lighting circuit is redundant, and this 6mm unsheathed wire is used instead. Strange but true, and it passes all tests with flying colours (except the one where someone holds it while a current is passed through!)

 

[hairyben]

Thanks Matthew

Yes, I agree, there are so many opinions that I thought I would get the inspector to tell me what he needs, but it rankles a bit if he's asking for what isn't required!

The house was built in 1959 and has modern plastic coated cables, except that the earth wire in the T&E lighting circuit is redundant, and this 6mm unsheathed wire is used instead. Strange but true, and it passes all tests with flying colours (except the one where someone holds it while a current is passed through!)

When twin & earth first started being used for lighting circuits, some of the ol' boys just chopped the earth off and continued as they'd done before with twin. Presumably the separate earth has been retro-fitted.

 

[ban-all-sheds]

I understood that we were under no obligation to change existing installations to meet current regs,

You aren't, and the electrician appointed by the council isn't saying that you do have to.

But your existing cpc does not comply with 543.3.2, and therefore cannot be used as the cpc for the new additions.

Instead he would like me either to run a fresh earth wire to the CU just for the en-suite (even though both en-suite fan and lights are double insulated and need no earth!) OR to use an existing 2.5mm spur to serve the lights as well, via a fused spur.

Does this sound correct?

Yes.

the earth wire in the T&E lighting circuit is redundant

What do you mean by that?

it passes all tests with flying colours (except the one where someone holds it while a current is passed through!)

¿Que?

 

[r.bob]

Thanks for the confirmation Ban.

When I said

the earth wire in the T&E lighting circuit is redundant

I was referring to the fact that although modern T&E is installed for the lighting circuit, the Earth is not connected to anything, just nipped off at each light, as Hairyben remarked, and a separate bare 6mm wire used as the earth. The logic for this escapes me, but the house was wired just as pvc cable was being introduced, and perhaps the sparks were thinking along the lines of "sod this new stuff, I'm installing it like I've always done!"

The last comment was a little joke, referring to the fact that the bare 6mm earth wire works as it should when tested, but obviously is not insulated should someone be holding it at the wrong time....

 

[electronicsuk]

Do you have enough slack on the cables in your lighting circuit to be able to strip them all back and re-terminate along with the integral CPC? That would alleviate the need for a separate earthing conductor for your additions to the circuit, and also help to bring the existing wiring inline with today's standards.

 

[ban-all-sheds]

The logic for this escapes me, but the house was wired just as pvc cable was being introduced, and perhaps the sparks were thinking along the lines of "s** this new stuff, I'm installing it like I've always done!"

Sadly, some electricians are characterised by superstition, ignorance and fear of anything new, and some take a perverse pride in not changing what they do in line with changes to the regulations.

Suggest though that this is in any way unprofessional and even those who don't agree with them close ranks and attack you for having the temerity to criticise the dangerous old dinosaurs.

 

[r.bob]

Sounds about right Ban....I'm just trying to imagine what was going through his mind as he clipped off all the ends of the earth wire...

Thanks Matthew, a good idea. The earth wire in the T&E cable IS connected to the CU, so I guess I could trace the relevant cable to ensure continuity from the en-suite. If that was tricky would it be acceptable to run a new earth from the en-suite light to where the T&E disappears below, (and use a JB to reconnect into the T&E) rather than having to route it all the way to the CU? Or is that a bit of DIY thinking??

I'm happy to use the alternative, ie the 2.5mm spur, but it would mean one extra FCU on the en-suite wall, as well as creating a spur on a spur.

 

[electronicsuk]

Thanks Matthew, a good idea. The earth wire in the T&E cable IS connected to the CU, so I guess I could trace the relevant cable to ensure continuity from the en-suite. If that was tricky would it be acceptable to run a new earth from the en-suite light to where the T&E disappears below, (and use a JB to reconnect into the T&E) rather than having to route it all the way to the CU? Or is that a bit of DIY thinking??.

Depends which bit of T&E you're talking about. If you're suggesting picking up an earth off a socket from the ring final then no, as any changes to or removal or that circuit in the future could give rise to a situation where the fixtures in the bathroom no longer have an earth connection. It's not safe to assume that anyone working on your electrical installation will be aware of where you've picked the earth up from.

If, however, you're suggesting picking up an earth from the CPC of the initial length of T&E cable that feeds the lighting circuit to the bathroom, that should be acceptable as long as you can confirm there is a good earth path back to the CU.

 

[r.bob]

Thanks again Matthew.

Yes, it was the second "if" that I had in mind.

Cheers, Bob

 

[dingbat]

The logic for this escapes me, but the house was wired just as pvc cable was being introduced, and perhaps the sparks were thinking along the lines of "s** this new stuff, I'm installing it like I've always done!"

Sadly, some electricians are characterised by superstition, ignorance and fear of anything new, and some take a perverse pride in not changing what they do in line with changes to the regulations.

Suggest though that this is in any way unprofessional and even those who don't agree with them close ranks and attack you for having the temerity to criticise the dangerous old dinosaurs.

No closing ranks here.

I see these same dangerous old dinosaurs every working day... and I criticise the Bejasus out of 'em.

 

[ban-all-sheds]

OK -

Suggest though that this is in any way unprofessional and even some of those who don't agree with them close ranks and attack you for having the temerity to criticise the dangerous old dinosaurs.

And naming no names, some of the rank-closers frequent this forum...

 

[Click-Sure]

I helped a guy out at his house who was qualified to 11th (yes, eleventh) edition!

Must take him up on the offer of borrowing his old regs books one day, the have a look and see how far we've come!

 

[ban-all-sheds]

I helped a guy out at his house who was qualified to 11th (yes, eleventh) edition!

1939-1950.

Someone who left school early and was apprenticed under that version and never bothered to update could still have been wiring houses to that standard into the 1990s...