Conductors in parallel......

[kingeri]

I was at a job on Friday in a big 4 storey house. One of the jobs I was there to do was to add sockets to a bedroom which actually didn't have any at all. The top floor sockets were on there own breaker, a 32A RCBO actually. There were two 4mm^2 T&Es at the RCBO so I initially thought it was a ring. When I found the other ends of these cables in the top floor loft area, they were both terminated in a junction box and a 2.5mm^2 ring was run from there. So, a lollipop circuit with conductors in parallel forming the initial feed (the 'stick' of the lollipop). I actually didn't have time to start the sockets so I will be there tomorrow to do it.

I am interested to know who would leave the circuit as it is and just add the sockets to the ring part of the circuit, and who would convert the circuit into a full ring (easily done with an extra JB next to the existing one). The last option would obviously result in a ring with 4mm^2 legs of equal length and the 'loop' section in 2.5mm^2. Thanks!

 

[Octopus]

Did you do a Zs on the existing set up?

If the Zs is low, could you disconnect on 4mm and redo it, to see if the Zs is OK

and then if it is then you could use the 4mm which is now spare and extend it to form a radial or another lollipop

 

[telectrix]

maybe the 4mm was used to avoid volt drop? if i read yur OP right, you have a rfc with the initial feeders fun in 4mm. reducing to 2.5mm on the top floor.

 

[kingeri]

I haven't done any tests yet, it was 4.30pm on Friday and I didn't want to start anything I had no chance of finishing. I think one 4mm would be adequate, the run can't be more than about 10 meters.

Tel - it's not a RFC, the feeders are joined in a JB and the ring is taken from there.

 

[telectrix]

got you.

 

[kingeri]

Crazy thing is there are only 3 double sockets on the ring at present.

 

[Richard Burns]

Since it is easy to get to the junction box then I would try and separate them into a ring. But with just three sockets is it worth the effort.
I have left a few lollipop rings in that situation where it is not possible to easily get to the point of junction, so long as it meets the regulations' requirements then it is just another circuit, albeit non standard. No, not a circuit that is not listed in the OSG, surely that is illegal!

 

[Wilko]

Weird
I'd convert it to be an RFC - reason being to easily confirm ring continuity from board or any accessory (for some future test say). IIUC to convert it you just redo that jb?

 

[kingeri]

I can easily convert it to a full ring by chopping a couple of sockets in nearby and taking the feeds into them then onto the existing and new sections of the ring. I could also create two radials at 20A, which may be a better option. Hmmm. The mind boggles.

 

[Octopus]

No, not a circuit that is not listed in the OSG, surely that is illegal!

ha ha ,where is your horse!

 

[Octopus]

I can easily convert it to a full ring by chopping a couple of sockets in nearby and taking the feeds into them then onto the existing and new sections of the ring. I could also create two radials at 20A, which may be a better option. Hmmm. The mind boggles.

Do you have space for another RCBO?

 

[kingeri]

Since it is easy to get to the junction box then I would try and separate them into a ring. But with just three sockets is it worth the effort.
I have left a few lollipop rings in that situation where it is not possible to easily get to the point of junction, so long as it meets the regulations' requirements then it is just another circuit, albeit non standard. No, not a circuit that is not listed in the OSG, surely that is illegal!

I do believe the circuit is fully compliant (pending the outcome of my tests tomorrow) as it is, and though not a 'standard circuit', it is a bit weird and in this case, pointless.

Do you have space for another RCBO?

Yes, it's a Wylex NSB type. Plenty of unused ways.

 

[kingeri]

This house already has 6 socket circuits, one more wouldn't hurt!

 

[westward10]

Have you posted this before because it sounds very familiar.

 

[kingeri]

Have you posted this before because it sounds very familiar.

No, but I did post ages ago about a ring with 4mm legs. Similar situation here but different!

What are your thoughts on this one??

 

[Ian1981]

Sounds like a hybrid/ring circuit where you may have as an example ,an old 6mm twin that was used for a cooker circuit, then a ring final is ran from the 6mm , all connected in an contactor or isolator fed from a 32mm OCPD

 

[westward10]

I would leave as it is, just a personal preference but I don't like ring final circuits made up of conductors with differing csa.

 

[kingeri]

I would leave as it is, just a personal preference but I don't like ring final circuits made up of conductors with differing csa.

I know what you mean. I think I might use one 4mm^2 to serve the existing sockets in bedroom 1 as a 20A radial and use the other to serve my new sockets in bedroom 2 and on the landing on a second 20A radial.

 

[Toneyz]

Is this bedroom with no sockets on the same floor as the other sockets ?.

 

[kingeri]

Is this bedroom with no sockets on the same floor as the other sockets ?.

It is indeed.