Routing of meter tails

[leep82]

hi all any advice on the following scenario much appreciated. I have taken on a rewire from another electrician whos personal circumstances mean he cant finish the project. Majority of the first fix has been completed including the repositioning of the DB. The original DB was situated inside the kitchen base units adjacent to the meter and cut out. I can see why the DB is being moved as it isnt the most accesible of places and a new utility room is being created which is much more suitable. However it is the routing of the new ‘ tails’ that im not 100% comfortable with.

25mm double insulated tails along with a 16mm CPC have been run at low level behind the new kitchen base units before rising up in a PVC trunking to ceiling height. They then run approximately 8mtrs through the joist before again dropping down in a PVC trunking to what will be the new DB position. At no point are they buried in a wall. Personally i would have used 16mm2
T&E but the ceiling is now boarded and skimmed so the customer and builder is very reluctant to drop the ceiling and allow me to do this. The intention is to provide our own overcorrect protection at the origin so as not to be solely relying on the 100a DNO fuse.

Ive searched varies threads looking for an answer or advice so apologies if this has been done to death. Can anyone point me in the right direction of where to look in the regs or offer any other advice

 

[leep82]

So what do you think that tells you Leep82

It doesnt tell me im wrong as its all opinion. No install method mentioned is a deviation from the Regs and nobody has said i shouldnt use T&E because of ........ My prefence would be SWA>T&E>insulated/sheathed tails, but it all depends on the installation.

 

[Midwest]

It doesnt tell me im wrong as its all opinion. No install method mentioned is a deviation from the Regs and nobody has said i shouldnt use T&E because of ........ My prefence would be SWA>T&E>insulated/sheathed tails, but it all depends on the installation.

You not alone, I've seen quite a few such distribution circuits done with tw&e. If done correctly, there's nowt wrong with it. Prefer to allow using swa myself.

 

[Deleted member 26818]

You can use T&E if you want.
The CPC will have to be a minimum CSA of 10mm2 if PME conditions apply.
Where the cable passes through joists or battens above a ceiling or below a floor, it will have to be a minimum of 50mm from the surface of the ceiling or floor, or provided with mechanical protection.
If it’s concealed in walls it will have to be at a minimum depth of 50mm or in a prescribed route and provided with 30mA RCD protection.

 

[stevels4]

I wonder who is going to break the seals on the cut out and meter and remove the fuse in order to install the load tails and KMF unless there is already a double pole isolator fitted.
It is coming up to Christmas so perhaps the "Seal Fairy"
I guess the tails from the cut out to meter are also 25mm and fully tightened?

 

[Octopus]

Whats a seal?

 

[Pete999]

Whats a seal?

 

[davesparks]

Yeah im not saying its by any means fool proof, i just feel theres more chance of striking more than just the one conductor when using a T&E

Actually with the theee separate single core cables properly bound in a triangular formation you’d be more likely to hit more than one core with a screw as they overlap better in all planes.

But ‘more likely to hit’ is irrelevant and offers no protection.

 

[davesparks]

Without wanting to sound stupid what is tht earthed armour offering ?

That earthed armour is offering protection from electric shock for anyone damaging the cable with a metal object.
The point of having earthed armour on a cable is to connect any metal object which penetrates the cable to earth before it makes contact with any live conductor, this in turn ensures operation of the protective device.

 

[Percyprod]

You must have some means of protection at meter position, dno fuse is NOT acceptable, it is to protect the dno's system, not the installation.

 

[leep82]

That earthed armour is offering protection from electric shock for anyone damaging the cable with a metal object.
The point of having earthed armour on a cable is to connect any metal object which penetrates the cable to earth before it makes contact with any live conductor, this in turn ensures operation of the protective device.

Yes i agree, so by that token does a metal object have more chance of striking the CPC in a T&E than it does if using insulated/sheathed tails? Im not trying to argue against SWA, its the best method discussed on this thread. I was just asked what benefits a T&E would have over tails and for me this is it. Granted its by no means a certainty and as none of the install methods are not to current regulations it doesnt actually matter, but my personal opinion is the T&E method has advantages over 25mm tails

 

[Toneyz]

Apart from the use of SWA I think we are getting into the argument of good practice.This supply in "meter tails" should not be protected by the DNO protective device.

 

[leep82]

Apart from the use of SWA I think we are getting into the argument of good practice.This supply in "meter tails" should not be protected by the DNO protective device.

It wont be

 

[EbolaSideRoom]

Would it not be better to extend the supply via SWA from a DP Switch Fuse?

Would be my best case scenario too, if budget & circumstances allow.
If the 25mm/16mm tail kit is in place (and there will be suitable DP switched fuse after the meter) I don't see a problem.

 

[leep82]

Would be my best case scenario too, if budget & circumstances allow.
If the 25mm/16mm tail kit is in place (and there will be suitable DP switched fuse after the meter) I don't see a problem.

Yea guys this is the best scenario however the 25mm tails are already in and ceilings boarded and skimmed. The debate has gone slightly off topic and benefits of other methods are being discussed

 

[davesparks]

Yes i agree, so by that token does a metal object have more chance of striking the CPC in a T&E than it does if using insulated/sheathed tails? s

You’ve missed the point, it is not about striking the cpc, it is about making contact with earthed metal first.
Yes there might be slightly more chance of hitting the cpc, but that’s no good if the metal object has gone through the live first and injured or killed the person holding it.

‘More chance’ doesn’t offer any protection at all.