Socket Wiring Advice

[nero44]

Thanks Harry. Few questions on this please for my understanding:

- If it turns out to be a 1.5mm cable, can this remain in place if used in conjunction with a fused spur and would the fused spur need to be installed at the JB before the 1.5mm cable commences or does that not matter?
- Although not pretty, is it possible to used a switched fused spur as regular light switch? Then a quick fix would be to swap the existing light switch with a switched fused spur
- I assume a fused spur unit always needs to be accessible for inspection and cannot be buried inside the wall? Feels a bit overkill to install a separate fused spur switch in the wall for 7w of LED lighting. It's in my son's room and he never uses this, so might do away with it completely.

 

[Harry Bloomfield]

- If it turns out to be a 1.5mm cable, can this remain in place if used in conjunction with a fused spur and would the fused spur need to be installed at the JB before the 1.5mm cable commences or does that not matter?

It would need to be connected on the input to the switch, to the ring, or a spur off the ring, using 2.5mm. You are not permitted to wire anything connected directly to the ring, using smaller than 2.5mm.

- I assume a fused spur unit always needs to be accessible for inspection and cannot be buried inside the wall? Feels a bit overkill to install a separate fused spur switch in the wall for 7w of LED lighting. It's in my son's room and he never uses this, so might do away with it completely.

You could rewire it in flex, fit a 13amp plug, and simply plug it in.

 

[nero44]

It would need to be connected on the input to the switch, to the ring, or a spur off the ring, using 2.5mm. You are not permitted to wire anything connected directly to the ring, using smaller than 2.5mm.



You could rewire it in flex, fit a 13amp plug, and simply plug it in.

Ah these are recessed mini spotlights and all built in already with all wires behind walls. I might upload a picture to illustrate.

But this actually brings up another problem. The ring is quite large already and has many sockets, but it's only running on a 20a RCBO. My sparky who did the recent EICR recommends upgrading to a 32a RCBO, but this then would cause an even bigger problem if there is any unprotected 1.5mm cable somewhere along it? What is your view on this?

 

[Harry Bloomfield]

But this actually brings up another problem. The ring is quite large already and has many sockets, but it's only running on a 20a RCBO. My sparky who did the recent EICR recommends upgrading to a 32a RCBO, but this then would cause an even bigger problem if there is any unprotected 1.5mm cable somewhere along it? What is your view on this?

No need to upgrade, unless you are tripping it, but if there is 1.5mm it needs to be resolved.

 

[robinbanks]

...what?

Rated/designed for that many wires. A 24amp wago for example might well be 6 port but it don't mean it's wise to use it to piece four 2gang sockets into a ring even if it is bob on equidistant to the CU down each leg..

 

[securespark]

Use 32A?

 

[EFLImpudence]

It would need to be connected on the input to the switch, to the ring, or a spur off the ring, using 2.5mm. You are not permitted to wire anything connected directly to the ring, using smaller than 2.5mm.

Not actually the case, so...

 

[Harry Bloomfield]

Not actually the case, so...

The OP mentioned lights, wired with 1.5mm, apparently unfused, spurred off the ring.

 

[EFLImpudence]

Well, there are lots of ifs and buts in this thread, but...

You are not permitted to wire anything connected directly to the ring, using smaller than 2.5mm.

...is not true.

 

[Ragnar_AT]

If the whole circuit is on a B20 MCB it doesn‘t even have to be a ring.

 

[SUNRAY]

If it's on a B20 then it's not a special case ring final and a 1.5mm² spur feeding a 3A SFCU is permissible.

 

[EFLImpudence]

Everything seems to be made unnecessarily complicated lately.

If it's on a B20 then it's not a special case ring final and a 1.5mm² spur feeding a 3A SFCU is permissible.

Or not feeding a 3A FCU as the CCC Method C of 1.5mm² T&E is 20A.

Even on a 32A special case ring final a 1.5mm² spur feeding a 3A - or 13A - FCU is permissible as would no FCU if conditions were met for omission of overload protection..

 

[nero44]

Some updates, as I finally had time to take another closer look at this... Following a "tug of war" resulting in a few scratches on my hands, I managed to remove all the old pushfits without cutting any cables and reconnected with Wago221s for now, as this made testing a bit easier.

For a start, there is actually no 1.5mm^2 cable in that junction, which I suppose is good news. The cable queried by SUNRAY, is actually going up into the loft, where it is feeding two sockets (one spurred off the other). Since the first socket is considered to be on the ring final (via JB), I assume it's fine to have one spur having a total of two sockets in the loft. Not that it matters, but they are basically unused as my loft is technically an unhabitable space.

However, after testing for continuity with all ends I found out that:
- Only 1 and 3 have continuity and therefore form the ring final
- 1 also has continuity with the socket, which I previously thought was served by cable 2.
- 1 is ALSO connected to the LED lights
- 2 is therefore still unidentified, which is annoying

I've attached a picture of the room so you can get an idea of how it actually looks like.

When I replaced the light switch on the left side, I could actually see that there is a JB (these round metal 30A heavy duty ones) screwed onto a batten inside behind the plasterboard. So I assume that cable 1 comes up from the CU, splits somewhere under the floor and goes behind the plasterboard to feed the Led lights AND the socket below the lights. It would then also have to continue to meet the rest in the wall on the right side.

So this could actually make things easier. I wanted to move the middle socket out of the skirting, but did not want to chase into the middle of that wall, which is solid plaster on brick and also a good space for a double bed sometime in the future. But now it looks like I might have access to the ring final in the left side behind the plasterboard, which is where I wanted to relocate the socket to anyway >> Just on the right-inside, inside the left empty bottom shelf. If I need to install a 3A FCU for the LED lights, then actually that would also be a decent place to put that as it would be neatly tucked away. If this turns out to be possible, then the socket in the middle could just be disconnected wholly?

I assume LED drivers never have a fuse inbuilt? i.e. from a safety perspective my best hope would be that the previous sparky took the 2.5mm^2 through a fuse behind the plasterboard to downrate for the LED? I don't want to open the entire wall so not sure if I will be able to make out the bit from the JB to the actual LEDs, but will try.

 

[nero44]

Update:

So I decided to cut a hole in the plasterboard to see the wiring. It's quite simple, the spur comes in with a 2.5mm^2 wire and enters the black 30a JB. From there it splits down to serve the socket in the middle (in 2.5mm^2) and another 1.5mm^2 cable goes from the black JB into the smaller white 5a JB. From there it's just standard light wiring feeding the LED's above via the switch.

@Harry Bloomfield (et al.) can you confirm that the safest way forward is to install a 3a fuse between these two Junction Boxes? Strictly speaking I should run a 2.5mm^2 off the black into the fuse and then a 1.5mm^2 from the fuse onwards into the white JB?

 

[Harry Bloomfield]

@Harry Bloomfield (et al.) can you confirm that the safest way forward is to install a 3a fuse between these two Junction Boxes? Strictly speaking I should run a 2.5mm^2 off the black into the fuse and then a 1.5mm^2 from the fuse onwards into the white JB?

Better (if I understand it correctly) would be to take the 2x 2.5 straight into a switched 3amp fused spur unit, then from that in 1.5mm or 1.0mm. Do away with the JB's completely.