Extending Ring Main in place of existing socket

[killercowuk]

Am looking to extend my ring main by 4 sockets from a socket that is no longer required (at its present location) and wanted to check if the following solution (using materials I have to hand) meets all the required regulations.

Untitled

• killercowuk
• 23 Mar 2014
• 1

I've attached a diagram of a double socket metal back box that I would like to fill with 6 30amp connector blocks. The ring circuit is on a 32amp rcd protected circuit. I will be placing a blanking plate over it.

Would this approach meet regulations and the approval of your helpful sparky selves?

Thanks

 

[EFLImpudence]

Yes, it would but you could leave the socket there and just use three connectors.

Assuming it IS a ring and not a spur with another spur.
It probably is a ring but you should check by testing continuity between the two Ls, Ns and CPCs.

 

[Spark123]

The only thing I'd recommend doing differently is losing the link between the earths on both legs and bonding the back box to one leg only, the way you have drawn causes a figure of 8 on the earths and can cause slight issues when testing.
I take it you are leaving it accessible too.

 

[killercowuk]

Yes, it would but you could leave the socket there and just use three connectors.

I did think about this however this is a socket in the new office room I'm working on where I am planning to make all sockets on what was an old water heater circuit instead - the extra 4 sockets are for room next door and this socket provided most convenient access to the ring main.

Having some sockets on the ring main and some on a seperate circuit could possibly be confusing? Would hate someone to cut power to all office sockets to then discover one socket it still powered via ring main?

What do you think?

Assuming it IS a ring and not a spur with another spur.
It probably is a ring but you should check by testing continuity between the two Ls, Ns and CPCs.

Thanks for pointing out I'll double check this!

The only thing I'd recommend doing differently is losing the link between the earths on both legs and bonding the back box to one leg only, the way you have drawn causes a figure of 8 on the earths and can cause slight issues when testing.
I take it you are leaving it accessible too.

Interesting I hadn't considered this. I thought maximum earth contact would be the way to go (from my electronics and electrical engineering studies ). From an electricians point of view are there tests this will interfere with?

Thanks guys

 

[Spark123]

r1+r2 measurements will go up and down, the value is meant to be constant around all sockets on the ring. (r1+r2 is where the L and E are crossed at the CU, not to be confused with R1+R2)

 

[killercowuk]

r1+r2 measurements will go up and down, the value is meant to be constant around all sockets on the ring. (r1+r2 is where the L and E are crossed at the CU, not to be confused with R1+R2)

Ah yes, makes sense. Thanks for clarifying - I'll remove the earth "bridge" between circuits and keep it to Ring 2 only.

 

[JohnW2]

I've attached a diagram of a double socket metal back box that I would like to fill with 6 30amp connector blocks. The ring circuit is on a 32amp rcd protected circuit. I will be placing a blanking plate over it.

You've probably already though of this, but ....

... your diagram indicates that the blanking plate will be metal. That being the case, I would personally suggesting running a connection from the earthing terminal on blanking plate (there should be one) to the earthing terminal in the back box, rather than relying on the faceplate screws to establish that connection. I admit that one needs a fairly good imagination to come up with scenarios in which the blanking plate might otherwise become 'live', but for the sake of a little bit of wire, it would, IMO, probably be worth doing. Others may, of course, disagree!

Kind Regards, John

 

[killercowuk]

... your diagram indicates that the blanking plate will be metal. That being the case, I would personally suggesting running a connection from the earthing terminal on blanking plate (there should be one) to the earthing terminal in the back box, rather than relying on the faceplate screws to establish that connection.

Yep - fair recommendation. Metal is the blanking plate I've got sitting here but possibly plastic (for the sake of a quid or two) may be the safer option then?

 

[JohnW2]

Yep - fair recommendation. Metal is the blanking plate I've got sitting here but possibly plastic (for the sake of a quid or two) may be the safer option then?

Well,plastic is obviously 'safer', and raises no questions about earthing it, but if you want to have a metal one there's no reason why you shouldn't - particularly if you included an earthing wire as I suggested.

Kind Regards, John