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Its TN-C-S with 100amp cutout fuse (Although might only be a 60 or 80 amp fuse in the carrier but says 100amp so have to presume). Tails look really small, have not taken it apart but looked at next doors that had been cut off and I would say they are 10mm tails so really need upgrading. I thought the regs say they only need RCD protection if more than 3 meters, cable length will not be more than 3 meters, but thought there had to be some mechanical protections.

How about a large wiska box with a couple of henley blocks inside to make connection between tails and swa?

Saying that trying to get even 2 core 25mm SWA though the cavity could be a problem so may not have a lot of choice.

On a TNCS or TNS system 16mm tails are ok with a 100A cut out fuse providing the installation meets the following 2 criteria:

1. Max demand of the installation (taking into account diversity) should not exceed the CCC of the 16mm tails.

2. Regulation 434.5.2 has to be met (i.e protection of the tails against fault current).
This regulation will always be met on a TNCS system as long as Ze<0.35Ω which it should be.
It will be met on a TNS system is Ze<0.48Ω as at that value K²S²>I²t (just!)
 
Could you not put some sort of trunking/conduit on the outside of the building, up from the services box? Or if you're going to use SWA, run that up the outside clipped direct then straight through the wall to the back of the DB.
 
Could you not put some sort of trunking/conduit on the outside of the building, up from the services box? Or if you're going to use SWA, run that up the outside clipped direct then straight through the wall to the back of the DB.
I agree with that. I have looked into using the copex before but always come up with a different solution as I just think it would be a right pain and expensive. I usually use 25mm conduit on the outside of the wall. 2 x 25mm and 1 x 16mm just squeeze in. For a longer run you may need 32mm conduit which would be a pain as its not as easy to buy all the bits that go with it.
 
I dislike meter tails in cavity walls. Any cables for that matter, but especially nice thick meter tails with no RCD protection - just ready for someone drilling through the wall for an outside light feed etc.
 
Is this unacceptable for meter tails >3m in a cavity wall/ceiling as per the regs ?.
Saw a client today who wanted to move some sockets. Installation about 3 years old but with no certificate or labels on the CU.
25mm meter tails ran in cavity of wall/ceiling for around 4m to the CU.
Tails ran from a double pole isolator.

Tails in cavity wall 20190522_133603 - EletriciansForums.net
 
No overcurrent present protection for tails longer than 3m.
 
Hi - I’m always happy to learn, but I don’t see a reg in BS7671 that says you can’t run cables in a building void, with greater than 50mm cover, properly done with no installation damage etc. I don’t do it, but there’s tons of homes with tails done that way.
If I was there to install outlets they’d be done by now :) .
 
It was a regular thing to put tails in cavities yes. Not necessarily a good thing though.
 
This was the board the tails were fed into. No fire barrier were the cables enter the CU at the back either albeit installed recently. Looks like the IP rating is not too good either with all that white paint

Tails in cavity wall 20190522_135039 - EletriciansForums.net
 
Is this unacceptable for meter tails >3m in a cavity wall/ceiling as per the regs ?.
Saw a client today who wanted to move some sockets. Installation about 3 years old but with no certificate or labels on the CU.
25mm meter tails ran in cavity of wall/ceiling for around 4m to the CU.
Tails ran from a double pole isolator.

View attachment 49492


so to protect the tails with an rcd may prove very inconvenient if there is a fault which would wipe out all of the board, but this has to be weighed up against the risk of tails in cavity/ceiling <50mm
 
Why do the tails need RCD protection, if they are run in a cavity, or have I missed a pertinent post again?

Fire barrier; would it not be just the meter tails coming out of the cavity, that would require sealing?
 
The tails are around 5 metres long, fed through a wall cavity and ceiling. They have no mechanical protection and at points are buried at a depth less than 50mm.

At the points where they are less than 50, can they not be capped with a suitable capping?
 
I could only see the start of the run from the DB back to the cut out which was less than 50mm.
I suppose the problem is that as I can not see the run as a whole Im not sure what is less than 50 and whats more than 50mm.
Albeit not ideal a RCD main switch would offer protection ?
 
Tails look really small, have not taken it apart but looked at next doors that had been cut off and I would say they are 10mm tails so really need upgrading. I thought the regs say they only need RCD protection if more than 3 meters,

So you looked at the tails next door to establish what is required in the house you are working on?
 
I’ve re-read your OP. I think I would consider routing an swa cable from the meter box, terminating it in one of those bracket things or metal adaptable boxes, running cores straight out through suitable gland. In the meantime ask the supplier to install one of their isolators. Is the run 3 or 5 meters?
 

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