Extending a ring main in a garage-just need a junction box?

[skotl]

Having a bit of brain fade on this, so appreciate any guidance.

Last year, the builders' electrician wired up my garage - put in a CU with one circuit for the 32amp welder, lights on another circuit, then four metal-clad sockets on a ring on another circuit.

All above board, tested and notified as per building works we had in the house (Scotland).

Of course, I now find that four sockets is nowhere near enough.

So my plan is to extend from the final socket along the wall and fit another two x 2 gang metal clad sockets, returning back into the ring.
All of that is fine - what I'm having a brain-fade with is how to bring the new return and join it to the old return (i.e. the return from the currently final socket).

I don't want to replace the cable back to the garage CU mainly because I don't want to touch the CU. So I disconnect the return from the (current) final socket and connect it to the new return via an old-fashioned 20A junction box, right?

It seems simple - so just wanted to check.

Supporting info;

1. The new sockets will be within ~10ft of the current final socket,
2. The entire run, including current and new, is around 20ft of the garage CU, so 40ft on return
3. All sockets plus the junction box are mounted directly on the wall and are fully accessible
4. The total load on the ring main is a single power tool, plus spotlights, radio, battery charger, etc. Total load unlikely to exceed 1.5 x yer average power tool.



Summary - I can use one of these to extend a ring main?
http://www.alertelectrical.com/prodvar/5814/4-terminal-20a-junction-box

 

[ban-all-sheds]

You could do that.

Or you could not use a JB, and remove the cable connecting socket #3 to #4 and extend the ring from #3, through the 2 new ones to #4.

 

[ericmark]

The two methods I tend to use are either a twin (not double) socket box and two single sockets or a 4 module grid plate and two single sockets the latter means no switches on sockets. If keeping to metal clad then a conduit nipple and some 20mm nuts to space them.

 

[skotl]

Cool - thanks guys.

Think I'll go with b-a-s' option as that will be neater, given the layout in the garage.

 

[JohnW2]

The two methods I tend to use are either a twin (not double) socket box and two single sockets or a 4 module grid plate and two single sockets ...

I think I must be having a dumb moment (I've only just opened a bottle, so it can't be that yet ), but I'm not quite sure in what situations (and to achieve what) you are saying that you use one of those two methods.

Kind Regards, John

 

[diyer56]

I think ericmark is referring to using the two single sockets in place of an existing double socket to extend the ring. In this configuration the incoming existing ring cable could be connected to the left (for example) socket along with the new ring cable. The ring can then loop through the new sockets and return to the right hand socket. There it will be joined to the existing return cable.

 

[JohnW2]

I think ericmark is referring to using the two single sockets in place of an existing double socket to extend the ring. In this configuration the incoming existing ring cable could be connected to the left (for example) socket along with the new ring cable. The ring can then loop through the new sockets and return to the right hand socket. There it will be joined to the existing return cable.

Right - yes, of course! I must need a second glass

Kind Regards, John

 

[skotl]

...
Right - yes, of course! I must need a second glass

Kind Regards, John

I do find that this often helps