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

 

[Spark attitude]

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

 

[westward10]

I don't see a problem.

 

[leep82]

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

Would have been another option prior to ceilings being boarded and skimmed although maybe difficult to run a SWA through the joists.

 

[westward10]

What proplem/issue are you seeing.

 

[Pete999]

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

These "double insulated tails" the should be described as Insulated and Sheathed tails, I know I'm pedantic

 

[telectrix]

fit a 80A KMF after the meter. then connect existing tails. no problem.

 

[leep82]

I don't see a problem.

Maybe there isnt. I may be looking for one because its not how i would have done it myself. On the surface it all seems ok. Its just the length of those tails and more the fact that they run through the joists like they do

 

[Midwest]

I suppose only one issue is how they have been installed through the joists, but not sure tw&e would solve that.

 

[westward10]

These "double insulated tails" the should be described as Insulated and Sheathed tails, I know I'm pedantic

PVC/PVC conductors, animals have tails

 

[westward10]

Maybe there isnt. I may be looking for one because its not how i would have done it myself. On the surface it all seems ok. Its just the length of those tails and more the fact that they run through the joists like they do

6181Y conductors are no different to T&E with regards to the construction of the insulation and sheathing.

 

[stevethesparks]

Why would the op want to reduce the cabling to 16mm T&E?

 

[Midwest]

Why would the op want to reduce the cabling to 16mm T&E?

To be fair, installing 6242y thru joists is easier than 6181y cable IMO. But then I would of used 6943x cable any way, which is a whole lot more of a sweat.

 

[Midwest]

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

I know its been covered before here, but have you covered your botty, taking on the completion of someone else's installation?

 

[westward10]

To be fair, installing 6242y thru joists is easier than 6181y cable IMO. But then I would of used 6943x cable any way, which is a whole lot more of a sweat.

Jobs been done for him though.

 

[Midwest]

Jobs been done for him though.

I know, I was just expressing my opinion, before someone challenged my design

 

[leep82]

Thanks for the comments guys, would it be

I know its been covered before here, but have you covered your botty, taking on the completion of someone else's installation?

Fair point raised and if it was sombody who i didnt know from adam then i would be very reluctant to do so. However i have worked with the electrician who has carried out the work so far and am more than comfortable picking it up from him. As things stand the vast majority of his 1st fix is still visible to inspect, its just the route that the new tails take that has been the first area handed over to the plasterer. Would it be worth installing a 100ma time delay RCD as a belt and braces approach?

 

[westward10]

If it is a TN system an rcd is not required.

 

[DPG]

, its just the route that the new tails take that has been the first area handed over to the plasterer. Would it be worth installing a 100ma time delay RCD as a belt and braces approach?

What protection are you giving by adding a 100mA TD RCD though?

And changing to T&E wouldn't improve things over the tails that are there already. Can't see the sense of pulling the celing down.

 

[Midwest]

I'm confused, I understand a distribution circuit only requires disconnection time of 5 secs (411.3.2.3), but does not reg 522.6.202 apply?

Edit; assuming cables are installed below flooring of less than 50mm.

 

[stevethesparks]

I was confused as thought the CU should be within 3 metres of the meter, unless I've misread something?
Edit: if directly fed from the meter

 

[westward10]

His intention is to fit circuit protection at the source.

 

[Midwest]

I'm confused, I understand a distribution circuit only requires disconnection time of 5 secs (411.3.2.3), but does not reg 522.6.202 apply?

Edit; assuming cables are installed below flooring of less than 50mm.

And my query Westward?

 

[Octopus]

I can't see what fitting 16mm twin and earth would help? Especially as the cpc size would be too small

 

[westward10]

And my query Westward?

The OP states they are not buried in a wall but yes Reg 522.6.201 would come into play. Fit swa

 

[Deleted member 26818]

522.6.201 can be complied with in a number of ways.
As far as I am aware, RCD protection is not one of them.

 

[Ian1981]

I can't see what fitting 16mm twin and earth would help? Especially as the cpc size would be too small

The cpc in the 16 mm would only be the distribution circuit cpc and not the main earthing conductor (that’s if a suitable sized conductor will be installed at the origin) so depending on the zs at the consumer unit it will most likely be satisfactory for use as a cpc only.
Tho If your bonding conductors are connected at the consumer unit then it’s another story....

 

[Octopus]

Tho If your bonding conductors are connected at the consumer unit then it’s another story....

hit, nail and head .....

As we don't have all the information, my observation stands...

 

[westward10]

Doesn't matter the 16.0 is not relevant in this case.

 

[PEG]

Going away from who has the biggest core...

Is the OP concerned about the vulnerability of the animal wagging parts,where they have been installed?

I get the feeling,this may be his concern.

 

[leep82]

If it is a TN system an rcd is

Going away from who has the biggest core...

Is the OP concerned about the vulnerability of the animal wagging parts,where they have been installed?

I get the feeling,this may be his concern.

sorry for the late reply, yes this is a concern. It is a TN system NOT TT so as pointed out earlier in the thread RCD protection not required.

 

[DPG]

Animal wagging? I've checked the regs and I can't find this.

 

[leep82]

I can't see what fitting 16mm twin and earth would help? Especially as the cpc size would be too small

A seperate cpc would have been run along with the T&E

 

[Midwest]

sorry for the late reply, yes this is a concern. It is a TN system NOT TT so as pointed out earlier in the thread RCD protection not required.

Thought you said the tails were installed under floorboards, are they more than 50mm...?

 

[leep82]

Thought you said the tails were installed under floorboards, are they more than 50mm...?

Yes they are although i didnt install them myself

 

[Midwest]

Which goes back to the dilemma of you first energising part of an installation, someone else has installed. Not trying to be clever, just wonder how you would cover yourself on the EIC, not having inspected after installation.

Must be a solution, as this happens more than not?

 

[leep82]

Which goes back to the dilemma of you first energising part of an installation, someone else has installed. Not trying to be clever, just wonder how you would cover yourself on the EIC, not having inspected after installation.

Must be a solution, as this happens more than not?

Fully agree and as mentioned if it wasnt an install previously started by another electrician i trust i would not have taken the job. I guess im more concerned about the use of the double insulated meter tails. Althought they are ran together and at a suitable depth ( 50mm from floor and ceiling ) i still worry that either conductor could become damaged and the fault not clear, the use of a T&E or SWA would surley reduce this with all conductors being enclosed together.

 

[DPG]

I still don't see how T&E would be an improvement??

 

[leep82]

Which goes back to the dilemma of you first energising part of an installation, someone else has installed. Not trying to be clever, just wonder how you would cover yourself on the EIC, not having inspected after installation.

Must be a solution, as this happens more than not?

Fully agree and as mentioned if it wasnt an install previously started by another electrician i trust i would not have taken the job. I guess im more concerned because of the cable

I still don't see how T&E would be an improvement??

wouldnt you have more chance of hitting multiple conductors in a T&E, say with a nail or screw and in turn creating a short circuit causing my OCPD to operate. The way that the cables are installed shouldnt give rise to this happening, but whats stopping Mr Builder sending a 3” screw into a floorboard?

 

[DPG]

You cant rely on t&e to perform like that.

And as long as the cables are correctly installed then screws aren't a problem. You might as well say what if he uses 6 inch nails.