Moving a Consumer Unit and need to extend some cables

[mattcos1972]

Hi Guys and Gals,

I am about to change an old fuse board which has been grossly overpopulated with the circuits on its 5 fuses over tens of years of electricians swinging by on their horses!

At the moment the board is about 6" off the floor at the back of the broom cupboard so I would also like to relocate it to be at a more accessible height. The meter is outside the house directly behind (and a little higher than) the fuse board in its current location. I have my provider coming in to install a DP Isolator between the Meter and the FB and they are also gonna change the talis as they are still 16mm jobs. When they come I will get them to reroute the tails in so they can accommodate the proposed location of the new CU. There is also an SWA cable servicing my shed which can be rerouted for higher entry through the wall without the need to extend. Meter tails will be under 3m in length after relocation.

So far so good................however the cables to the house circuits are coming in from under the floor boards and I have a pretty good idea that a few, if not most, of them cannot be extended enough to reach the proposed new location. What is the best way (7671 compliant) to join these cables and make them longer; either under the floor or in a wall mounted box?

Here's a few things to bear in mind. I will be rewiring the house at a later date when I have more time (its my home btw) also I will be having building control signing the work off as I am not Part P as yet. Also, and probably most importantly on this job. NICEIC will be coming down to inspect the work as its one of my pieces towards getting on their scheme. lol

Any advice would be greatly appreciated; and thanks in advance for taking the time to read / answer this post.

Matt

 

[acat]

I would crimp the cables that need to be extended and use the heat srink over the crimping just make sure that its solid and all reading are acceptable.


Hope that helps



Chris

 

[mattcos1972]

I would crimp the cables that need to be extended and use the heat srink over the crimping just make sure that its solid and all reading are acceptable.


Hope that helps



Chris

Hey Chris,
Thanks for getting back to me chap.
If I use crimps and heat shrink are they ok to slip back under the floorboards 'as is' or will they need to be located in a box? I want to make sure I am absolutely compliant, Of course my exwife will argue that that would be a first

 

[Graeme Harrold]

Make sure you use a ratchet style crimper as this will ensure the correct pressure is applied to the joint. DONT use the pliers style as you will not be able to judge a consistent crimp. Once covered with heat shrink they are deemed permanent, and can be placed out of sight (under floors, in walls etc). Just test your cables before you hide them again.

 

[mattcos1972]

Make sure you use a ratchet style crimper as this will ensure the correct pressure is applied to the joint. DONT use the pliers style as you will not be able to judge a consistent crimp. Once covered with heat shrink they are deemed permanent, and can be placed out of sight (under floors, in walls etc). Just test your cables before you hide them again.

Thats great, Graeme. I have ratchet crimpers so no worries there.

Thanks for the advice guys.
I'll keep you posted on my exploits lol!!

Would heat shrink butt connectors, such as these, be suitable for the job of crimping?

Partex UK - Pre-Insulated Crimp Terminals

 

[Davey101]

The cables would need to be fixed to something, or the crimps need to be inside a proper enclosure. If both ends are 'loose', i.e. just hanging under the floor, then whats to stop them from being pulled out of the crimps? Same thing if you are using a joint box,according to regs the box must incorporate a cord grip, to stop the cables being pulled out.

If it were me, my house and it was temporary, I'd just crimp and tape them. If I was worried about strain on the cables, I would tyrap the two T+E's together. Bit different if someones going to be inspecting it though

 

[mattcos1972]

If it were me, my house and it was temporary, I'd just crimp and tape them. If I was worried about strain on the cables, I would tyrap the two T+E's together. Bit different if someones going to be inspecting it though

Ain't that the truth!

Cheers Davey101. You've put up a strong argument for a joint box with cord grips there lol!

 

[Davey101]

Ain't that the truth!

Cheers Davey101. You've put up a strong argument for a joint box with cord grips there lol!

Dont forget that any joint box with screw connections must be accessable (so I'm told)

 

[mattcos1972]

Dont forget that any joint box with screw connections must be accessable (so I'm told)

And another good argument for bunging said joint box on the wall! lol!!

I would probably be more inclined to keep it below ground and crimp though as there is plenty of room down there and as I said it is purely temporary so even if I use individual joint boxes on each cable (there's only 7 or so) its not going to be too unruly and there's plenty of room 'neath the floorboards.

Cheers again chap!