meter tails in cavity wall

[scott g]

just been to qoute a fuse board change meter tails in 16mm 80amp main fuse in meter head cutout
question is changing fuse board and tails but i think im going to have to put a 30ma 100 amp rcd time delay on
tails is this the only way to get round this problem with tails in cavity?

Do ‘meter tails’ concealed in walls or partitions need to be protected in accordance with Regulations 522.6.6 and/or 522.6.8?

NDA4
Yes. Meter tails concealed in a wall or partition at a depth of less than 50 mm from a surface must be protected in accordance with Regulation 522.6.6. Also, irrespective of the depth from a surface, meter tails concealed in a wall or partition having internal metallic parts (except nails and screws, etc) are subject to the requirements of Regulation 522.6.8.

However, additional protection for meter tails by means of an RCD is not an acceptable option in respect of Regulation 522.6.7 (which in consequence rules out reliance on 522.6.6(v), routing in the ‘safe zones’ alone), or in respect of Regulation 522.6.8(v). Also, for TT systems, the only option remaining is to provide suitable mechanical protection (that is, to comply with Regulations 522.6.8(iv) and/or 522.6.6(iv) as appropriate).

 

[ian]

If tails are running straight through a cavity there is no RCD protection required, if the cables are running up or along a cavity there is still no RCD protection required because they will be concealed greater than 50mm deep, however you my need to account for thermal characteristics etc.

If for any reason you do need to fit a rcd to meter tails because it concealed in a wall less than 50mm deep, there is not a lot of point fitting a RCD CU, just need to note it on the certificate as a deviation to the regs.

ian

 

[Burnt Fingers]

At some point and almost certainly to coincide with inspection my CU is going to have to move and I will need longer tails, through a cavity wall, with a total run of 1.5m to Henley block. I was going to use flexicon tubing for tails and cables (cavity is insulated, cables will be >50mm deep) because its easy to get up teh cavity and then very easy and neat to pass the cables. I'm wondering if flexicon tube counts as mechanical protection though - I'm referring to the plastic not the steel types.

I'm familiar with galv trunking, and SWA but 25mm SWA? Yikes. Any thoughts?

 

[Burnt Fingers]

Oh Forget that post. It will have to be galv for the tails