Can I join 2 radials to make a ring?

[Longhorn]

I have 2 radial lines coming out of our CU in 2.5mm that used to run storage heaters, but have now been replaced with a double outlet on each (they are both powered from the same MCB). I have a couple of questions:

Can I join these together to turn it into a ring?
If so, would this constitute notifiable work?

Thanks in advance.

 

[Andy78]

I have 2 radial lines coming out of our CU in 2.5mm that used to run storage heaters, but have now been replaced with a double outlet on each (they are both powered from the same MCB). I have a couple of questions:

Can I join these together to turn it into a ring?
If so, would this constitute notifiable work?

Thanks in advance.

Any work done should be compliant with the wiring regulations. This includes testing to ensure safety and a certificate producing to prove this.

Notification is a separate and additional requirement to those of the wiring regulations.

 

[westward10]

There is no reason why this cannot be done but I see you have no electrical qualifications, why is it necessary to do this.

 

[Longhorn]

Thank for the replies. Westward10, you're absolutely right I have zero qualifications, hence asking here whether it is theoretically possible. It would not be my intention to do this myself, I'm just throwing the question out there to see if I'm overlooking something at this planning stage.

As a bit of background, the whole house is wired with radials. These two particular ones are relatively modern and my assumption would be that they would be infinitely more flexible with regards to extending their usefulness if they were part of a ring. My theory is that they could be joined together and have other sockets added, thus creating a modern ring where once there were just 2 radials.

 

[westward10]

Yes this can be done whether this makes it more flexible is debatable as radials themselves can be added to much more easily. Why not just split them onto their own 20A protective devices. What locations would they be serving.

 

[Longhorn]

Thanks Westward10. When you say radials can be added to more easily, do you mean adding more radials or adding more sockets to an existing radial? the latter seems to me akin to spurring off of a spur so I assume you mean the former.

I'm trying to keep disruption to a minimum so adding more radials would be a pain in the rump. Running a cable from the end of one one radial to the other goes right by where we could use another couple of sockets, so this seems to be the easiest way forward and something of a win-win.

 

[westward10]

If you create a ring final circuit and fit a 30/32A protective device you restrict yourself as to the amount of outlets on a single radial spur unless you fit a 13A fuse connection unit or alternatively you have to incorporate them into the existing ring final. A 20A radial is not so restrictive as you can just add on at various points as you like assuming the cables are suitably rated.

 

[Longhorn]

So if a spur was taken off of the existing 2.5mm radial and the radial was protected by a 20A MCB at the CU this would be perfectly safe and within regulations?

 

[westward10]

Yes assuming the cable is suitably rated.

 

[westward10]

You need to assess the potential loading of your new sockets, if they are in bedrooms or the lounge then loading is likely to be low so 20A would be ample but if it is a kitchen and heavier appliances are using them then a ring final circuit maybe a better option. A good electrician should give the correct advise.

 

[Sparkingmad]

Longhorn in your post you say that joining the 2 radials together to form a ring the wiring route runs past the room/s you will be wanting to add extra sockets to. So extending 2 radials to get sockets in positions you want or need is infact no harder than joining them together to form a ring. The question you also have to ask yourself is rcd protection for the modified circuit or circuits. The 2 points were they night storage heaters? Are they live or are they still on off peak supply? I would recommend going the same route as westward suggests not knowing what board you have.

 

[Longhorn]

Sparkingmad; you're absolutely right, simply extending the radials to add extra sockets would be marginally easier than creating an actual ring as it would save me joining them together, but I didn't know this was possible. My theorising, and the reason for the question, was based on my longterm believe of 2 things: 1) You can't spur off of a spur, and 2) the ring main was designed just after the war when copper was at a shortage and a ring can be made in 2.5, thus saving copper (I infer from this that radials were heavier gauge before the ring was invented).

Based on those 2 points I reasoned that as these radials are 2.5 (and thus similar to a spur in handling capability, albeit directly from the CU and not from an existing socket) it would be safer, and indeed more in keeping with ring spec, to just join them together and form a ring, which would also allow me to add more sockets ad hoc.

As far as loading goes, they are all upstairs right now, so mostly bedroom stuff (phone chargers, toothbrush charger, etc, and periodically the vacuum). Heaviest draw would be my iMac and standard lamps plugged into the walls. Although there is a possibility to incorporate a connection to my shed, so there may be a little heavier draw on it with certain power tools.

 

[Longhorn]

Yes assuming the cable is suitably rated.

Is the rating of a cable simply a question of its size? It's 2.5, does that make it suitably rated? Or does one 2.5 differ from another?

Please forgive the apparent schoolboy questions, I'm just trying to get a handle on how much can be achieved with the minimum disruption. These radials have been sympathetically installed and are pretty unobtrusive. If I can extend their usability and increase our safety in the house without ripping them out and effectively putting them straight back again I'm up for that.

 

[westward10]

2.5 is generally adequate although installation methods will be a factor. Altering a circuit will require some testing to ensure the existing and new parts provide suitable circuit protection and the provision for additional protection by way of a suitable rcd.

 

[telectrix]

as said before, easier to add to a radial as there's no restriction like with spurs off a ring. the other advantage of extending the radials and leaving them as radials is that if you have a fault on one and need to isolate it till rectified, the other one still works. put each on a 20A MCB

 

[Longhorn]

...put each on a 20A MCB

Each on its own MCB or can they share?

 

[telectrix]

better on separate MCBs so as to split them, this helps with division of circuits as per 17th edition, esp. if each is on a separate RCD/RCBO.

 

[Sparkingmad]

Each radial goes on its own mcb longhorn

What he was saying is if one radial has a fault you leave that one off and the other still works, if it was a ring main you would lose all the sockets until a professional can get out and test and locate fault and fix it

 

[Longhorn]

I don't have nearly enough MCBs for that. Apart from the kitchen (ring) the whole house is on radials, many of which are sharing MCBs. This is another reason for the ring idea. If I could join those newer radials to form a ring I could eradicate many of the older radials and free up some MCBs.

 

[Sparkingmad]

Sparkingmad; you're absolutely right, simply extending the radials to add extra sockets would be marginally easier than creating an actual ring as it would save me joining them together, but I didn't know this was possible. My theorising, and the reason for the question, was based on my longterm believe of 2 things: 1) You can't spur off of a spur, and 2) the ring main was designed just after the war when copper was at a shortage and a ring can be made in 2.5, thus saving copper (I infer from this that radials were heavier gauge before the ring was invented).

Based on those 2 points I reasoned that as these radials are 2.5 (and thus similar to a spur in handling capability, albeit directly from the CU and not from an existing socket) it would be safer, and indeed more in keeping with ring spec, to just join them together and form a ring, which would also allow me to add more sockets ad hoc.

As far as loading goes, they are all upstairs right now, so mostly bedroom stuff (phone chargers, toothbrush charger, etc, and periodically the vacuum). Heaviest draw would be my iMac and standard lamps plugged into the walls. Although there is a possibility to incorporate a connection to my shed, so there may be a little heavier draw on it with certain power tools.

This is way way before my time and the cable was imperial and not 2.5mm. I think the recommendations then still allowed the use of the BC plug adaptor to connect your iron to the light pendant . Plus the wire was tin plated back then and let's be honest you would only have had 1 maybe 2 single sockets in each room. Most people now have more sockets behind their TVs than they had in the whole house in the 40's and 50's. I'm sure there are a few here that remember those days