Best Method for Splicing into a Radial Power Circuit?

[Ultim8Powers]

Hi everyone, looking for a bit of advice on extending an existing radial circuit in my home (England, UK). I'm fairly experienced with basic electrical works, and regularly convert homes to 'smart homes', however the following has me stumped.

The house was rewired 5-6 years ago, prior to my purchase.

Which of the following would you recommend as "best" (I suspect both are probably ok, with option B being the easiest):

A) Breaking into / splitting the radial (sorry about my terminology):


Or, B) Splicing into the radial:


A few other queries connected to the above:

1. From my research I'm getting conflicting information about the number of permitted outlets on a spur:
   • Radial Circuit | Wiring a Radial Circuit | Electrical Circuits | Electrical Wiring - https://www.diydoctor.org.uk/projects/radialcircuit.htm - states that only a single outlet per spur
   • House Wiring for Beginners - DIYWiki - http://wiki.diyfaq.org.uk/index.php/House_Wiring_for_Beginners - shows multiple outlets per spur
2. Is the existing 16B MCB sufficient, from my research it should really be a 20A MCB? Some some sources state that 16A is ok, others quote regulations that a radial should be on a 20A MCB. Considering that I'm more than doubling the outlets, I suspect I need to upgrade to 20A?
3. Is it ok to place junction boxes in the ceiling void (they will be inaccessible once the new plasterboard goes up). I don't really fancy the extra chasing required to spur from the existing sockets. Are Wagos ok in the ceiling void, within Wago boxes of course?

 

[littlespark]

From your first link, that means only one UNFUSED spur from a ring circuit.
If the spur is fused down, then it can have more than one, treated as a radial off a ring.

As for your project... you can add more sockets to a radial as you need them, but obviously you can’t use a great amount of electricity from them. 16 or 20, either would be fine depending how the 2.5 cable is run. (Less for running through insulation, for example)
It’s good practice to have as little joints as possible, so splicing would be better than cutting in and extending.

Would it be possible to convert this to a ring?

 

[Wilko]

Hi - my 20p

• simplest circuit design is best.
• no it’s not ok to create inaccessible joints in ceilings unless you have skills and material to make a Maintenance Free junction.
• the current rating of the circuit depends on both the conductor size and how it’s been installed. If the 2.5mm cable is running in the ceiling is covered by thick insulation that may explain the existing 16A MCB.
• have you thought about how you will test for Zs on your new outlets?

 

[Ultim8Powers]

Thanks for the prompt replies, super helpful.

I'm not opposed to making this circuit into a ring final. I have a twin blade chaser and a clear route back to the consumer unit, so a good suggestion. The only problem may be where I have 3 sockets together, would this require a fused spur, I think not as it would be two separate spurs off a single socket in the loop (4 wires into the 'master' socket is not ideal but unfortunately unavoidable in this position).

The sockets only serve a Living Room and Play room, thus only going to be running a TV, Laptop, table lamps, small gadgets and the occasional Vacuum Cleaner, however I think I will still convert to a 32 amp ring final to allow for future abuse (future owner may plug in a bunch of heaters lol).

The existing the cables were not run through insulation, but I plan to pack the ceiling voids full of acoustic insulation before installing the new ceiling.

I will pull new cables where possible to avoid hidden junctions, sticking with layout 'A' to maintain a compliant ring. I am competent enough to form MF junctions where necessary, I just wasn't sure if it was permitted for power circuits. Most of the existing drops are in oval trunking within the walls so hopefully not too hard to pull some new wires through.