Spurs, mixed from junction and socket

[ash_scotland88]

Can't quickly find the answer(s).

 

I know you can't spur a spur, so to speak. But can a ring mains with a spur from a junction box be mixed with spurs from sockets?

 

From memory it'll be no biggy to put into a socket now if it can't be, just there will be a junction box and join left in place as a negative. Adding more sockets to the study and will almost be a 1 spur per socket for ease for the sockets above desk height.

[markc]

I know you can't spur a spur, so to speak. But can a ring mains with a spur from a junction box be mixed with spurs from sockets?
so a room with a ring but also containing a radial so to speak (socket fed direct from CU). Nothing I know of to say you can’t,  but a note to say that socket has its own feed would be prudent.

[ash_scotland88]

(can a mod love to correct forum please?)

 

I know why I supplied the socket from a junction box-  existing runs being plastered in the wall.

 

But I totally get what you are saying. Although, in theory, anyone opening the socket will see that it's only one lot of cables. And anyone who doesn't won't know, much the same as a normal spur, there's no physical difference on the outside to say that can only take 20amps.

[Rob99]

These extracts from the wiring regs might help to explain..........

 

 

[Carrerahill]

52 minutes ago, ash_scotland88 said:

Can't quickly find the answer(s).

 

I know you can't spur a spur, so to speak. But can a ring mains with a spur from a junction box be mixed with spurs from sockets?

 

From memory it'll be no biggy to put into a socket now if it can't be, just there will be a junction box and join left in place as a negative. Adding more sockets to the study and will almost be a 1 spur per socket for ease for the sockets above desk height.

I am struggling to work out what you are trying to do. When you say spur do you mean a spur leg of wiring or a fused spur? What you can do if you must create a spur with multiple sockets from a ring is fit a fused 13A spur then run a radial to as many sockets as you want, safe in the knowledge you cannot overload that cable.

 

The reason you cannot spur off a spur is due to cable ratings, 32A ring main only works on 2.5mm cables because you have two of them, however if the circuit was a radial at 20A (which means the cable is then rated higher than the breaker) then you can actually create spurs from spurs because the whole thing is then only 20A. 

 

 

 

Edited February 28, 2022 by Carrerahill

[ash_scotland88]

Excuse the links to websites, and appologies my terminology may not always be correct.

 

So this is what is currently in place:

https://flameport.com/electric/socket_outlet_circuits/ring_circuit_overview_spur_jb_T.png

 

If I spur from socket with current set up then this would be the case:

https://www.diydoctor.org.uk/project_images/spursocket/Spurs_from_ring_main.jpg?ezimgfmt=rs:298x143/rscb98/ng:webp/ngcb98

(but a few more spurs from sockets)

 

 

What I was wondering if by having a spur from junction is there then limitations on the number of total spurs from sockets allowed? Or if by good practice the type (junction Vs socket) should be kept to only one type in a circuit? And there for best practice I should change the spur from junction to spur from socket

 

Edited February 28, 2022 by ash_scotland88

[Carrerahill]

11 minutes ago, ash_scotland88 said:

Excuse the links to websites, and appologies my terminology may not always be correct.

 

So this is what is currently in place:

https://flameport.com/electric/socket_outlet_circuits/ring_circuit_overview_spur_jb_T.png

 

If I spur from socket with current set up then this would be the case:

https://www.diydoctor.org.uk/project_images/spursocket/Spurs_from_ring_main.jpg?ezimgfmt=rs:298x143/rscb98/ng:webp/ngcb98

(but a few more spurs from sockets)

 

 

What I was wondering if by having a spur from junction is there then limitations on the number of total spurs from sockets allowed? Or if by good practice the type (junction Vs socket) should be kept to only one type in a circuit? And there for best practice I should change the spur from junction to spur from socket

 

My honest opinion is that you should get an electrician in. 

[TonyT]

If you change that double socket to a switched spur ,you can have unlimited socket outlets on it, as the switches spur will only allow you to pull 13 amp 

[ash_scotland88]

Right now I have sat down and hopefully dont have the other half yabbering in my ear about something distracting my train of thought....

 

Current set up is a ring mains with a spur from junction.

I am looking to add more sockets and essentially rewire the study, at this part of the ring. I will be adding more sockets into the ring, keeping it as a proper ring circuit but also for ease was thinking of making the sockets above the desk height as spured from socket below. This will be one double socket from one double socket. But as there is already a spur from junction I was unsure if this would even limit the number of spur from socket.* And/or best practise now the opportunity presents itself I should change the "spur from junction" to a "spur from socket".

 

*my understanding is that for each socket on a ring main you can have one unfused spur per socket. So if it's 10sockets you can spur a further 1 (unfused) off each making a total of 20.

 

(drawings can also be provided if required for further clarification)

Edited February 28, 2022 by ash_scotland88

[elite]

So the lower sockets are on a proper ring? Then yes, you should be good to spur one socket from each, though I would probably extend the ring

 

Is the junction accessible? If not I would move this to spur from a socket

 

 

[PeterW]

The junction box worries me here - what sort is it as it should be accessible unless it is WAGOs or similar. 
 

Also, if you’re putting the sockets in, why not just exend the ring through them all and do it properly..? It’s 2 runs of cable not 1..??