Spur from a spur cable??

[Spinfaster]

Hi All,

I'm adding a new double socket in my living room, which I had intended to tie into an existing cable (that goes to an existing double plug - see pic) using a 30a junction box and create a spur. I've added the socket, run all the 2.5mm t+e behind metal shielding in a channel at the bottom of the wall and have now realised that the cable I was going to join into is already a spur, but one that comes directly from the consumer unit. It's not part of the ring because there only one cable going in, and no other cables coming out.

So my question is, can I create a spur from an existing spur cable (not from the socket). And if so, should I add a 13a FCU somewhere in the line?

Here is the existing situation

Here are what I think are the options to join the new double socket

The existing socket will be running a table lamp and a router. The new double socket will ultimately run the TV, Sky box, sound bar, FireTV stick and a media box.

Thanks in advance for any help!

James

 

[Andy78]

See appx 15 for arrangements concerning spurs and ring circuits.
Cables run at the bottom of the wall does not sound like they are in prescribed cable zones.
Can't you make this leg from the consumer unit it's own circuit appropriately rated ?

 

[Pete999]

Hi All,

I'm adding a new double socket in my living room, which I had intended to tie into an existing cable (that goes to an existing double plug - see pic) using a 30a junction box and create a spur. I've added the socket, run all the 2.5mm t+e behind metal shielding in a channel at the bottom of the wall and have now realised that the cable I was going to join into is already a spur, but one that comes directly from the consumer unit. It's not part of the ring because there only one cable going in, and no other cables coming out.

So my question is, can I create a spur from an existing spur cable (not from the socket). And if so, should I add a 13a FCU somewhere in the line?

Here is the existing situation View attachment 53653

Here are what I think are the options to join the new double socket View attachment 53655

The existing socket will be running a table lamp and a router. The new double socket will ultimately run the TV, Sky box, sound bar, FireTV stick and a media box.

Thanks in advance for any help!

James

If your drawing is correct then your circuit is not a spur it's a radial circuit
[automerge]1573046996[/automerge]

See appx 15 for arrangements concerning spurs and ring circuits.
Cables run at the bottom of the wall does not sound like they are in prescribed cable zones.
Can't you make this leg from the consumer unit it's own circuit appropriately rated ?

What Andy said

 

[telectrix]

what rating MCB?

 

[Pete999]

Hi All,

I'm adding a new double socket in my living room, which I had intended to tie into an existing cable (that goes to an existing double plug - see pic) using a 30a junction box and create a spur. I've added the socket, run all the 2.5mm t+e behind metal shielding in a channel at the bottom of the wall and have now realised that the cable I was going to join into is already a spur, but one that comes directly from the consumer unit. It's not part of the ring because there only one cable going in, and no other cables coming out.

So my question is, can I create a spur from an existing spur cable (not from the socket). And if so, should I add a 13a FCU somewhere in the line?

Here is the existing situation View attachment 53653

Here are what I think are the options to join the new double socket View attachment 53655

The existing socket will be running a table lamp and a router. The new double socket will ultimately run the TV, Sky box, sound bar, FireTV stick and a media box.

Thanks in advance for any help!

James

Do you own or know how to use the appropriate test equipment?

 

[Spinfaster]

If your drawing is correct then your circuit is not a spur it's a radial circuit
[automerge]1573046996[/automerge]

What Andy said

Ah ok. I never knew that a single line was actual a radial. The name suggests something different.
[automerge]1573048001[/automerge]

what rating MCB?

Not sure but I can check tonight

 

[Spoon]

Welcome to the forum mate.

I agree with @Pete999 but is it a radial circuit to the socket fed from a breaker in the CU or does the breaker in the CU also supply a ring main (final ring circuit) and the socket is just spured from the CU on the same breaker?

 

[Spinfaster]

Welcome to the forum mate.

I agree with @Pete999 but is it a radial circuit to the socket fed from a breaker in the CU or does the breaker in the CU also supply a ring main (final ring circuit) and the socket is just spured from the CU on the same breaker?

Not sure, I'll check tonight but I have a feeling it's the later, since I don't remember ever seeing a breaker just for the one double socket on a radial circuit.

This is why I'm wondering if I should add an FCU somewhere.

 

[Strima]

If this is a spur fed directly from a 32 amp MCB of a RFC then if possible fit a 20 amp MCB and make it a dedicated radial circuit.

 

[Pete999]

Welcome to the forum mate.

I agree with @Pete999 but is it a radial circuit to the socket fed from a breaker in the CU or does the breaker in the CU also supply a ring main (final ring circuit) and the socket is just spured from the CU on the same breaker?

Spoon the OP has stated that it is a sigle cable feeding the socket only 1 cable at the OCPD, assumption a Radial Circuit, but agree with your thought in different circumstances, if it wad fed from a RFC at the OCPD it would be a spur.

 

[Spoon]

Spoon the OP has stated that it is a sigle cable feeding the socket only 1 cable at the OCPD, assumption a Radial Circuit, but agree with your thought in different circumstances, if it wad fed from a RFC at the OCPD it would be a spur.

It's not part of the ring because there only one cable going in, and no other cables coming out.

I interpreted the above as 1 cable going to the socket and not the OCPD but I could be wrong..

 

[Pete999]

I interpreted the above as 1 cable going to the socket and not the OCPD but I could be wrong..

Take a look at the hand drawn sketch the first on, that and the OPs description was/is what convinced me it was a radial he was talking about, mind you I could be wrong as well, nobody is perfect Mate, least of all me.

 

[Spoon]

Take a look at the hand drawn sketch the first on, that and the OPs description was/is what convinced me it was a radial he was talking about, mind you I could be wrong as well, nobody is perfect Mate, least of all me.

The drawing does show a radial mate.
We will see what the OP comes back with after he has checked it tonight.

 

[Spinfaster]

Ok. So firstly thanks to everyone who’s provided info. Much appreciated. There’s still a chance I’m just gonna get someone in to sort the lot, mainly because of the location of the cabling being in a channel at the bottom on the wall.

But for the sake of interest, it turns out the radial circuit is on its own MBC in the consumer unit. The only rating I can see on it is B16, vs B32 for all the others.

So could I technically add a junction to this radial cable and power the new socket without needing an FCU?

 

[telectrix]

Ok. So firstly thanks to everyone who’s provided info. Much appreciated. There’s still a chance I’m just gonna get someone in to sort the lot, mainly because of the location of the cabling being in a channel at the bottom on the wall.

But for the sake of interest, it turns out the radial circuit is on its own MBC in the consumer unit. The only rating I can see on it is B16, vs B32 for all the others.

So could I technically add a junction to this radial cable and power the new socket without needing an FCU?

yes. just be sure to route buried cables in prescribed zones. and, of course, RCD protection is needed.

 

[Spinfaster]

yes. just be sure to route buried cables in prescribed zones. and, of course, RCD protection is needed.

With reference to the prescribed zones, am I correct in saying that includes 150mm around the top of a wall where it meets the ceiling? Does it need to be in conduit or shielded or can it just be sunk into mortar?

And yes, it's all RCD protected!

 

[Spoon]

Does it need to be in conduit or shielded or can it just be sunk into mortar?

It can just go in the mortar but may be best to stick some capping over it.

 

[telectrix]

With reference to the prescribed zones, am I correct in saying that includes 150mm around the top of a wall where it meets the ceiling? Does it need to be in conduit or shielded or can it just be sunk into mortar?

And yes, it's all RCD protected!

see spoon's pic in post #17.