Is this permissable? - Picture

[Grinning Grandad]

I am re-wiring a ring main. I have a problem in that there is an extension at the back of the house with 2 sets of 2 sockets both sets fed from a single 2.5 T&E from the infamous octopus. There is no access to the roof void to the extension and the cables have been plastered over/tiled over/welded in so they can't be pulled through. In short there is no way I can convert these sockets to be part of a new ring. The cable is relatively new and still sound (and connected correctly at all the sockets).
Looking at my picture, (top is how it is now, bottom is suggestion) would it be ok to connect the two cables to another cable (via a JB) as a new circuit of its own protected by a 20a MCB.

 

[THRIPSTER]

It is probably me but I cannot see the difference (electrically) between the first and second circuit diagrams and am therefore left wondering what you are trying to achieve?

 

[davelx]

The "now" drawing doesn't look like a ring final at all - it looks like a branched radial and is electrically identical to your proposed layout - it's just a physical difference.

So long as the "octopus" is accessible and the CPD v cable CCC rating (20A would be OK if wired in 2.5mm, subject to any derating factors), R1+R2, Zs, Vd etc are OK I see no problem with it.

 

[comms]

Well the only differnce between the pictures is that you have removed the octopus & inserted a modern JB.

And if the existing cable tests ok, crack on & extend as a radial back to the cu.

 

[Grinning Grandad]

Electronically there is no difference. Its just that I wanted to put all the sockets on one ring and remove the Octopus completly. As its impossible to include these 4 sockets in a ring I was just checking that there is nothing wrong in connecting a Radial circuit in this manner using a JB?

 

[ban-all-sheds]

Nope.

But what have you got against the octopus?

 

[Grinning Grandad]

I've nothing personal against the octopus, in fact I've become quite attached to it.
But over the years its become less of an octopus and more of an hexadecagon-opus

Time to let go I think.

 

[ban-all-sheds]

I see what you mean.

The natural and obvious time for it to go is when you remove all that old VIR....

 

[Grinning Grandad]

Already in hand, the final tentacle will be cut on Wednesday.