Extending ring main

[DIYSOS2018]

Struggling to draw this one out and make sense if I’m honest mate, but that’s ok I’m only a DIY‘er was just looking to broaden my horizons.

As I see it though I’ve 3 viable options

Extend the ring per the drawings
Strip the cable back and run 4mm2 from socket 1 to the first spurred socket, or
Run another 2.5mm2 from socket 1 to the first spurred socket - creating this figure of 8 thing

 

[EFLImpudence]

Run another 2.5mm2 from socket 1 to the first spurred socket - creating this figure of 8 thing

OR

Run another 2.5mm2 from socket 1 to the NEW socket - resulting in two spurs with only one double socket each.



I missed the bit in your original post asking to make it as complicated as possible.

 

[DIYSOS2018]

I missed the bit in your original post asking to make it as complicated as possible.

Fair point, but, it would be much easier to either extend the main circuit, or run the second lot of 2.5mm2 than it would be to strip back the current 2.5mm2 cable and re-run a 4mm2 cable.

I know you’ll wonder why... The current cable is in lots of mini trunking with various corners which is tightly packed. If I didn’t extend the ring main and simply ran the separate 2.5mm2 the cable would take a different route, almost equidistant but a much cleaner route!

Hope that makes sense

 

[DIYSOS2018]

Using the connectors will make the circuit a complete ring (with just one spur).

Every socket will have two cables (expect where the spur is).

This way you will be extending the ring (expect for the one spur).

If at 'socket one' you had all four cables directly all joined together, it wouldn't be a true ring. At this point you would have an interconnection, making the ring into a figure of eight.

Using the connectors makes it a true ring.

Draw it out with the four cables joined together.

Then do a drawing with the two cables jointed, and the other two connected to the socket.

If you trace all round the diagrams with your finger you'll see one works out to be a nice continous ring, albeit with one spur.

You should see the difference.

Sparkwright been trying to understand this one in my head.

Is the attached what you meant?

So basically the ‘ring in’ and the cable currently going to the socket gets crimped and the ‘ring out’ and the new cable being ran to the socket gets crimped, both going into the back of socket 1?

Does that stop this becoming a figure of 8? Is there any issue given I think socket 1 is first or second out of the CU, that part wasn’t just for illustrative purposes!

Cheers

 

[EFLImpudence]

All you will have done with that arrangement is use 2 x 2.5mm² (5mm²) in stead of 1 x 4mm².


What you must realise is that the ring is protected by a 32A MCB.

2.5mm² cable is only rated at 27A so you are only allowed one double socket because you can only plug in 2 x 13A fused plugs (26A) so the spur cannot be overloaded.
When you add the second double socket to that spur. it would then be possible (though highly unlikely) to plug in 4 x 13A loads (52A - though limited by the 32A MCB) which the first spur would have to carry.

To overcome this you must replace that spur cable with one (or two) that can handle at least 32A - 2 x 2.5 either in parallel as in the diagram OR by extending the ring OR using 1 x 4mm.

 

[DIYSOS2018]

Hi EFL

So your last paragraph

To overcome this you must replace that cable with one (or two) that can handle at least 32A - 2 x 2.5 either in parallel as in the diagram OR by extending the ring OR using 1 x 4mm.

...is that what I’ve just shown in the diagram I attached? Is that what sparkwright was getting at?

Current spur socket will only have 1 x 13A plug, a lay z spa, the remaining spurred socket again will only have 1 x 13A plug, a fridge freezer + a baton LED light.

 

[EFLImpudence]

...is that what I’ve just shown in the diagram I attached? Is that what sparkwright was getting at?

Yes, I think so.

Current spur socket will only have 1 x 13A plug, a lay z spa, the remaining spurred socket again will only have 1 x 13A plug, a fridge freezer + a baton LED light.

Ah, a different kettle of worms.

As you seem to have realised, two single sockets is the same as one double socket - better in fact.

A quirk in the regulations (in example diagrams; not the actual regulations) states that only one double socket is allowed on a spur. Some people interpret this as meaning that two single sockets are not allowed; I do not.
Obviously though it makes absolutely no difference electrically and one may design safe circuits in ways not drawn in example diagrams.

I would say you could just add your additional socket to the existing spur and it will be satisfactory. Others will disagree.

 

[DIYSOS2018]

So rather than leaving it as Lay Z Spa (spurred socket one) and fridge freezer (spurred socket two) which sounds like it should be fine?

if I followed my drawing above that would make it safer again? Yes?

 

[EFLImpudence]

if I followed my drawing above that would make it safer again? Yes?

Well, yes and no. It would not be unsafe if you did not do it like the diagram.

 

[DIYSOS2018]

Well, yes and no. It would not be unsafe if you did not do it like the diagram.

so.......

 

[EFLImpudence]

It's up to you.

 

[DIYSOS2018]

Does my most recent art work have any draw backs?

Any benefits over just adding a spur against the regs?

 

[EFLImpudence]

Does my most recent art work have any draw backs?

Not really - apart from unnecessary work.

Any benefits over just adding a spur against the regs?

No. I dont think it is against the regs - just people's inability to think.

 

[DIYSOS2018]

How do you mean EFL? I thought the regs, to put it simply, was only one spur off an existing socket on the ring?

 

[EFLImpudence]

It's not the actual regulations which state that; it is just a diagram of circuit examples which states only one double socket may be on an unfused spur.

That it does not also state two single sockets may be used does not mean they cannot be used as obviously it makes no difference to the circuit.

It also does not show the use of cable (4mm²) which can handle the current for more than two sockets.