Additional CPC... does it have to run in a zone?

[DNS1]

Got a load of stainless steel sockets and switches for my living room a while back, but never fitted the light switch as there's no cpc (current light switch is plastic).

Planning to drop a cpc down from the loft, but for one reason and another it's going to have to run diagonally across the wall (beam and board adhesive mean it can't drop down straight).

I know it's not ideal, but do the regs prevent the running of a protective conductor outside a zone?

 

[johnboy6083]

I think that it would be wrong to run it diagonally, but you can use steel conduit as CPC, and that can be run outside zones!

 

[GLENNSPARK]

Got a load of stainless steel sockets and switches for my living room a while back, but never fitted the light switch as there's no cpc (current light switch is plastic).

Planning to drop a cpc down from the loft, but for one reason and another it's going to have to run diagonally across the wall (beam and board adhesive mean it can't drop down straight).

I know it's not ideal, but do the regs prevent the running of a protective conductor outside a zone?

so what you mean is the walls have been drylined?...is the room decorated?....is the existing cable in channel?...if so all you do is use the old cable to draw a new one in.....and i wouldn`t be running it on the diagonal...or outside prescribed zones either....so if the cpc you run outside zones and diagonal (as you suggest)... gets drilled.....then you lose that cpc to a class 1 fitting......come on.....think about it.....

 

[trev]

I have to agree with Glenn, it's inviting disaster to run it diagonally. What I would do is get a tenon saw (Yes a wood butcher's toy!!!!) and gently cut from the ceiling to the switch point but not going all the way through unless you're cutting quite wide. You should then be able to prise that bit out, if you break it you can use it as a template for a new bit and dot and dab that bit in. Once it's replaced, fill up the cuts with an appropriate filler paint/paper over and jobs a goodun

 

[spark 68]

I don't really see the point of this question, as by the regs the CPC has to follow the same route as the existing cable and would need to be in 4mm.

So if the 'new CPC' has to follow the same route you may as well run T&E, as this is likely to cause the same disruption to decor etc.anyway

 

[DNS1]

Thanks for the advice guys.

It didn't sound right to run it diagonally, but seeing as it's not directly dangerous, it didn't sound wrong either! Now Glenn has mentioned the possibility of accidentally cutting it and never knowing, all becomes much clearer!

The walls are indeed drylined. I originally thought about using the existing cable to draw another one though, but it's stuck fast. I assume the plasterer dot and dabbed straight over the wiring!

Having thought about it a bit more, I reckon I can work out where the offending dabs of adhesive are, drill in and uncover the cable (power off of course!), free it and then use it to pull a new one through.

Was initially reluctant to damage the plasterboard (only just been redecorated!) but it wouldn't exactly be hard to make good.

 

[DNS1]

I don't really see the point of this question, as by the regs the CPC has to follow the same route as the existing cable and would need to be in 4mm.

Yeah, it's a fairly pointless question, but then I am only learning.

Thanks for pointing out that bit about the cpc having to follow the existing cable route. Didn't know that!

 

[spark 68]

The 4mm bit is important too! and is a bit tight to terminate.
I will look the reg up for you re: following the same route,.

I wasn't being snotty or anything, but I have had this conversation before with a customer.

 

[The Ranger]

The 4mm bit is important too! and is a bit tight to terminate.
I will look the reg up for you re: following the same route,.

I wasn't being snotty or anything, but I have had this conversation before with a customer.

excuse my ignorance why 4mm? mechanical strength?

 

[GLENNSPARK]

Thanks for the advice guys.

It didn't sound right to run it diagonally, but seeing as it's not directly dangerous, it didn't sound wrong either! Now Glenn has mentioned the possibility of accidentally cutting it and never knowing, all becomes much clearer!

The walls are indeed drylined. I originally thought about using the existing cable to draw another one though, but it's stuck fast. I assume the plasterer dot and dabbed straight over the wiring!

Having thought about it a bit more, I reckon I can work out where the offending dabs of adhesive are, drill in and uncover the cable (power off of course!), free it and then use it to pull a new one through.

Was initially reluctant to damage the plasterboard (only just been redecorated!) but it wouldn't exactly be hard to make good.

look mate.....say a fault occurs on a class 1....such as these metal wallswitches you plan to fit.....and theres no fault path back to the MET.....so you come along and touch the fitting..thus creating the fault path...now...depending on what type of fuse or MCB you have...together with the moisture content of your skin and what footware (if any) you are wearing etc....all these things will dictate the magnetude of the fault...or the shock you would recieve and the duration.....and you wouldn`t know that the integrety of the cpc had been compromised......

 

[DNS1]

The 4mm bit is important too! and is a bit tight to terminate.
I will look the reg up for you re: following the same route,.

I wasn't being snotty or anything, but I have had this conversation before with a customer.

No probs.

543.1.1 mentions the cross section, but I can't find the bit about following the same route as the rest of the circuit

 

[spark 68]

543.6.1 for the same route.

And it has to be 4mm, because the minimum is 2.5mm with mechanical protection, 4mm without. 543.1.1

 

[DNS1]

Thanks for that, 543.6 is open in front of me but I didn't read it properly!

Glad I'm getting some use out of my BGB!

 

[CrazyScozzese]

Are you sure it isn't easier to do what Glenn says and draw a new t&e in using the old cable? No plastering, no soft bendy 4mm going everywhere except where you want it.

 

[spark 68]

It will be difficult to terminate more than one 4mm cable at lighting accessories.

Iam still finding my way around the BGB too, Iam sure 534.6 was worded differently before, in an earlier edition perhaps.

 

[DNS1]

Are you sure it isn't easier to do what Glenn says and draw a new t&e in using the old cable? No plastering, no soft bendy 4mm going everywhere except where you want it.

old cable won't budge mate, think the plasterer must have slapped a great spodge of adhesive over it.

 

[CrazyScozzese]

I guess it was wishful thinking! Not ideal but is there a cavity?

 

[a1guvner]

old cable won't budge mate, think the plasterer must have slapped a great spodge of adhesive over it.

If it was dot and dab over existing walls wouldnt your old cable still be in the original containment and easier to work out where the plasterer may of stuck it, ps in hindsight if you know you didnt have a cpc originally before the work started would of been a lot easier back then to rewire the lot properly,

Just a thought for the future

 

[wildgoose]

Not as difficult as you think to get it down the wall. You only need to locate the studs (dabs in your case). Then locally create a small channel the in plaster only over these points. Use the voids between plasterboard and wall for the rest. You only then need to patch plaster little bits. For customers, would use quickset plater and you'll not have to come back next day!!

ps: use proper insulating rods to prospect the wall and not coat hangers. This minimises the risk of coming into contact with live wires - how often have you seen taped up bodges behind walls?

 

[DNS1]

Cheers guys.

I'll do a little investigating and replace the whole cable.