Adding to ring

[RobTi]

Hi I have the 2 ends of a ring main which come out of a plasterboard wall (in junction box), I am looking to add a double socket(just because I can while I am working at it) and a control for a couple of security lights (led lights for load if it makes a difference) and a control for an outside socket, so break the ring and add 3 loops between controllers and then connect ring back to the other end so completing ring, the 2 controllers I was thinking switched fuse spurs.
Is this okay or not ?
Thanks

Ps sorry for use of the word controllers

 

[EFLImpudence]

Yes, but surely you will have only two 'loops'.

The 'controllers' are Fused Connection Units - the cable from them to the lights is the Switched Fused Spur.

 

[winston1]

One "controller" would be a switched fused connection unit for the lights and the other a 20amp double pole switch for the outside socket.

 

[ban-all-sheds]

Is this okay or not ?

Is the circuit RCD protected?

 

[RobTi]

Sorry yes it’s only 2 loops between controls, this ring is on a separate circuit on fusebox(new one with breakers) forgot what this is called,I had an electrician install this ring in my attic when I got the fusebox renewed

 

[EFLImpudence]

Consumer Unit.

 

[ericmark]

You should before adding to a ring final measure the prospective short circuit current and/of loop impedance and/or resistance, and work out earth loop impedance and volt drop.

Often it is a simple push the button on the meter and you see your well within the limits so then simply go ahead, however you don't know until you have measured it.

Since the volt drop and loop impedance limits on a supply using a 13A fuse are greater than with a B32 MCB, if you can't measure then safer to use a fused connection unit. You will not find this in any official book, as if you can't measure you should not be doing the job, however I live in the real world.

I use to recommend using the EZ150 plug in tester, as it did measure loop, however think it has been recalled. Kewtech do one around £35 as does Socket and See similar price.

However they all seem to be for 20 amp radials not ring finals and pass at above the loop they should for a ring. Also the instructions are lacking and they don't tell you difference between TN and TT supplies. I am afraid it is a case where do you stop, an proper meter looking at around £250 for cheap one, then another £150 for the tester to test the meter with, same with proving for dead, not only do you need tester, you also need some thing to test the tester, all which gets a little silly for a DIY job.