Is this wiring method OK?

[MarkSmith]

Hi all,

Stumbled across an unusual piece of wiring in my house yesterday. The wiring which feeds the bedroom sockets is a normal ring for the most part - goes from CU to socket to socket to socket ... and back to the CU. However two sockets in one room are fed from a pair or spurs from a junction box.

I hope this will explain it better:

Untitled

• MarkSmith
• 26 Jul 2012
• 1

All cables throughout are 2.5mm T&E, and the ring is on a 30A breaker.

Judging by how tight one of the cables is, I think someone in the past has cut into the ring and added the junction box and the spurs.

Anyway, it seems unusual but is it "wrong"?

Thanks,
Mark

 

[JohnW2]

Stumbled across an unusual piece of wiring in my house yesterday. The wiring which feeds the bedroom sockets is a normal ring for the most part - goes from CU to socket to socket to socket ... and back to the CU. However two sockets in one room are fed from a pair or spurs from a junction box. Anyway, it seems unusual but is it "wrong"?

This is not, in fact, all that unusual. If it were just one spurred socket, or two connected to the ring at different junction boxes, it would certainly be fine - that's what unfused spurs are all about. Some might try arguing that to have two spurs originating from a single point on the ring is not ideal (although the regs don't say that this can't be done) - but, anyway, the perceived problems of doing this (potentially concentrating load at one point on the ring) are at their least important when, per your diagram, they are connected at roughly the 'middle' of the ring.

In practical terms, the greatest issue is whether the JB is capable of handling 4 cables satisfactorily (both mechanically and electrically) - but it probably is. Were it done today, the JB would have to be either 'accessible for inspection and testing' or consist of a 'maintenance-free' JB, but that requirement is not retrospective (unless the circuit is changed in some way.

Kind Regards, John.

 

[MarkSmith]

Thanks John, nice answer.

The JB is big (didn't notice a rating on it but definitely not a lighting one) and the cables fit without trouble. The was no sleeving on the earths (there is now - not sure if I was allowed to change that but too late now). It's also easily accessible.

Seems like not too much to worry about then.

Thanks!

 

[JohnW2]

Thanks John, nice answer. The JB is big (didn't notice a rating on it but definitely not a lighting one) and the cables fit without trouble. The was no sleeving on the earths (there is now - not sure if I was allowed to change that but too late now). It's also easily accessible. Seems like not too much to worry about then. Thanks!

You're welcome. Indeed, in all common sense terms, there's nothing to worry about - and I'm sure that there are countless similar examples 'out there'. A "Jobsworth" might look at the cable capacity marked on the JB - and would moan if it said, for example "3 x 2.5mm² maximum". However, if the cables 'fit without trouble', then my view would be to leave Mr (or Ms) Jobsworth stewing in his/her own juices! You probably wouldn't have to look all that far to find more than 4 cables in one 30A JB!

Kind Regards, John.

 

[MySparky]

Hi all,

Stumbled across an unusual piece of wiring in my house yesterday. The wiring which feeds the bedroom sockets is a normal ring for the most part - goes from CU to socket to socket to socket ... and back to the CU. However two sockets in one room are fed from a pair or spurs from a junction box.

I hope this will explain it better:

Untitled

• MarkSmith
• 26 Jul 2012
• 1

All cables throughout are 2.5mm T&E, and the ring is on a 30A breaker.

Judging by how tight one of the cables is, I think someone in the past has cut into the ring and added the junction box and the spurs.

Anyway, it seems unusual but is it "wrong"?

Thanks,
Mark

What's more perplexing about it is that someone has run two cables from a single junction box as spurs when they could have added two junction boxes in close proximity and simply extended the ring circuit.

 

[MarkSmith]

What's more perplexing about it is that someone has run two cables from a single junction box as spurs when they could have added two junction boxes in close proximity and simply extended the ring circuit.

They'd have needed a third length of cable (between the two "spur" sockets) to do that. The layout is such that that really wouldn't have been hard for them to do... my diagram doesn't show it, but the cable for one of the sockets runs right past the other one.

 

[JohnW2]

What's more perplexing about it is that someone has run two cables from a single junction box as spurs when they could have added two junction boxes in close proximity and simply extended the ring circuit.

Maybe the two spurs were added at different times, or maybe the path between the two sockets was not an easy one (so that the cable connecting them would have to go via a position close to the JB, hence being pretty long).

Although many seem to reagard it as 'not good practice', when one is near the middle of a ring, spurs are not, as far as I can see, really any 'worse' than an extension to the ring.

Kind Regards, John.

 

[Risteard]

Some might try arguing that to have two spurs originating from a single point on the ring is not ideal (although the regs don't say that this can't be done)

Are you sure about that?

 

[JohnW2]

Some might try arguing that to have two spurs originating from a single point on the ring is not ideal (although the regs don't say that this can't be done)

Are you sure about that?

Well, I'm certainly not aware of anything in the regs that says it can't/musn't be done - did you have a regulation in mind?

Kind Regards, John.

 

[MySparky]

What's more perplexing about it is that someone has run two cables from a single junction box as spurs when they could have added two junction boxes in close proximity and simply extended the ring circuit.

Maybe the two spurs were added at different times, or maybe the path between the two sockets was not an easy one (so that the cable connecting them would have to go via a position close to the JB, hence being pretty long).

Although many seem to reagard it as 'not good practice', when one is near the middle of a ring, spurs are not, as far as I can see, really any 'worse' than an extension to the ring.

Kind Regards, John.

I agree. In practice there's nothing wrong with spuring off a ring whether that's from behind a socket or by breaking into the middle of the ring somewhere. It'll still only draw 32A unless the owner plans to fire up an arc welder lol

 

[ban-all-sheds]

The only concern with using a JB to run multiple spurs from one point on the ring is that if you have too many spurs, and if it's too near the origin, you could overload the segment between the origin and the JB

 

[JohnW2]

The only concern with using a JB to run multiple spurs from one point on the ring is that if you have too many spurs, and if it's too near the origin, you could overload the segment between the origin and the JB

Indeed, and what has been described is just two spurs (with 5 sockets on rings) with them attached at roughly the mid-point of the ring - so I, for one, am completely comfortable with that.

Kind Regards, John.

 

[MarkSmith]

I must admit I didn't count the sockets on either side of the JB - that was just for illustration. There are (from memory) 17 (single or double) sockets on the ring (4 rooms plus landings) and I don't know whereabouts in the ring that JB is. It could easily be at/near one end of it.

 

[JohnW2]

I must admit I didn't count the sockets on either side of the JB - that was just for illustration. There are (from memory) 17 (single or double) sockets on the ring (4 rooms plus landings) and I don't know whereabouts in the ring that JB is. It could easily be at/near one end of it.

Don't worry. The regulations, per se, say nothing about a limit to the number of unfused spurs - and even the 'On Site Guide' which comes with the regs (but is not part of the regulations) merely suggests that the number of unfused spurs should not exceed the number of sockets on the ring. If the JB were near the end of the ring that is less nice - but still no worse than having two sockets close to one another at that point in the ring.

Kind Regards, John.

 

[RF Lighting]

It's one of those "not great but not really wrong" type situations...