House rewire

[mikec200_0]

HI Guys
I am currently renovating a three bed semi for myself and have done the first fix wiring myself I am a builder by trade but have a fair knowledge of electrics. The electrician i am using to 2nd fix and test is a young lad and seemed a little unsure when telling me how he wanted the meter tails and earth bonding so i thought i could run it by some guys that are proberly a bit more clued up on the latest reg's . He has told me to run 25mm tails and a 16mm earth to the new consumer unit which is approx 4mtr away from the metre box outside he said to run them through the cavity, he also said i only need to bond the main gas supply outside in the gas meter box and the mains water undersink in 10mm earth cable is this the case ?

 

[ezzzekiel]

Sounds about right - would offer some protection to cables through cavity

 

[poheZ]

I would check in your area the distance the DNO allows switchgear to be away from the meter postion, i would consider the run of the meter tails and whether they need extra protection than just secondary insulation, whether the walls have cavity insulation and where the water enters the house

 

[sparkylad]

Mike , has your electrician clued you up on the requirements of the building regs..i.e. Part P ? or is it covered under general building works notifications ?

 

[poheZ]

ahhh glorious, we all know the ways round part p, part p is like double yellow lines!

 

[mikec200_0]

Thanks for your replys and yes i have asked him to do the installtion to current part p and 17th edition spec as reguard to cables through cavity what would you recommend to cover them with ? Also the walls do not have cavity insultion and just wonderd is it a bad thing for you guys as reguard cables then ?

 

[ezzzekiel]

put some conduit in and draw cables through

 

[jeremy]

If it's metal conduit you use to protect the cables through the wall the phase and neutral must both go through the same piece, or you would get eddy currents induced in the conduit, so I've been told. Maybe someone a bit more theoretical on here can explain further? I'd run all three cables through the same piece but this will mean using bigger than 25mm and that brings issues with preparing the ends. Another, maybe easier,way might be to use a bit of 50mm metal trunking, which would be big and strong enough. To prep the edges to make them smooth either get some proper edging profile or strip off a length of insulation from a bit of 16mm so that it's a tube, make a lengthways slit in it and place over edge of trunking. Can anyone see a problem with this method, don't want to be passing off ideas as proven.Under 5 metres should be ok for a tail run, but the more they can be protected the better, as long as they're not smothered in insulation!!