Is this a spur?

[Dazzathedrummer]

Hi,

First of all, I consider myself a competent person, I do most of my own household electrics, I’m a qualified sound engineer and no stranger to a soldering iron.

Is this a spur? …the photos show our conservatory so what you’re seeing used to be an external wall. The dining room behind it has no sockets on the entire right hand side of the room.
I want to add two double sockets behind this wall and was thinking of extending the ring from this socket - I’ll need to re-think and probably tap into the kitchen.

The socket has two cables but one goes to a fused switch which runs to the conservatory lights - would this mean that the cable at the back of the switch box is a spur from another socket and the cable running back though the switch terminates at the lights?

 

[blup]

In all likelihood yes.

 

[Ragnar_AT]

Since there‘s two loads it would either have to be a radial circuit (16 or 20 A MCB in the consumer unit) or wired from a fused connection unit. You can’t have more than one double socket on an unfused 2.5 mm2 spur from a ring.

 

[ericmark]

As @Ragnar_AT points out, if there are two cables to a BS1363 device, then it is a fused spur or a radial if the installer followed BS 7671 when fitted, the problem is we can't guarantee that BS 7671 was followed.

However, should be easy enough to find what size breaker or fuse it is fed from.

 

[plugwash]

As @Ragnar_AT points out, if there are two cables to a BS1363 device, then it is a fused spur or a radial if the installer followed BS 7671 when fitted

The normative part of BS7671 has no such requirement, only the guidance in the appendix. The normative part of the standard only requires that the circuit be designed such that sustained overloading is unlikely.

I would argue that adding a light that draws bugger all to a spur that has a socket does not meaningfully change the risk of the spur being overloaded.

 

[ericmark]

When you took your BS 7671 exams, were any questions asked about the appendix? If one is expected to know the appendix, then one is clearly expected to follow the advice in it. It starts in the preamble for the whole book by saying it is not law but can be used in a court of law. So we are not forced to comply with anything in BS 7671.

But we may need to follow CENELEC Harmonization Documents, and the easiest way is to follow BS 7671 as it reflects what is required by the CENELEC Harmonization Documents.

 

[Dazzathedrummer]

Ok, thanks - I’ll assume it’s a spur and I can’t spur from a spur!

 

[robinbanks]

Can you find where this spur is sourced and convert it to a fused spur?

 

[Ragnar_AT]

So what size MCB is this fed from? If smaller than 32 A you’re good to go, if not, you need to convert this to a fused spur.

I think you could even have the FCU at the end of the feed, i.e. where the socket is now. Move the socket to the right, fit a single back box with an FCU where the feed comes in and you’re good to go.