Do Away With Ring Final Circuits?

[securespark]

 

[crystal ball]

Bring it on

 

[bernardgreen]

Keep rings ( properly installed and maintained ) and get rid of Slep and other incompetents like him.

 

[crystal ball]

Keep rings ( properly installed and maintained ) and get rid of Slep and other incompetents like him.

Thats the problem, many are not properly installed or maintained, who is Slep?

 

[ericmark]

To keep within volt drop rules with 2.5 mm² cable with a 25 amp MCB one is limited to around 25 meters, with same 2.5 mm² looking at 106 meters for a ring, so often you can't simply turn a ring final into two radials, and comply with volt drop.

7/0.029 is larger than 2.5 mm² so when the ring final was designed, with 30 amp fuse, even if the ring final was broken the overload was a lot less, and we should not have to plan for people fiddling and getting it wrong, the loop impedance tests every years should highlight any errors.

But to use radials means you really need 4 mm² cable so not a retro change. And I have found just as many 4 mm² radials where the person working on it clearly thought it was a ring and extended with 2.5 mm² as I have ring finals which have been broken, and broken ring is easy identified when testing, having a length of 2.5 mm² in the radial is harder to find.

But if we consider three 2.5 mm² radials can replace a ring final, then a home with three ring finals, then a 10 way consumer unit needs changing for a 16 way, with a cost of 6 extra RCBO's so the price is likely £70 more than with a ring final, which may be chicken feed with a re-wire, but on a new build home these pennies count.

Likely the kitchen is where ring final and radial will be most felt, if we follow the appendix and any appliance over 2 kW has dedicated feed great, but we don't, so a 32 amp ring with dish washer, tumble drier, and washing machine will hold in even with the odd boiling of a kettle. But that is not the case with 16 amp radials. So with radials you will need those dedicated feeds, so 6 RCBO's just for the kitchen.

I already have 16 RCBO's in this house, with his ideas with dedicated supply as appendix says, going to around 26 RCBO's not that I could do that as would also involve lifting floors, but if he wants radials he should leave the UK simple.

 

[sparkwright]

Ring circuits are brilliant.

 

[Diver Fred]

B-I-L has just come away from a job where recons that chap has wired the house.

He spent half a day there working through what is in place; packed his kit up and told the householder to get the bloke who wired the house in its present form to come and sort it out and do the job. Only room he was happy with was the utility room - 1 circuit per socket outlet with 3 single sockets in the room. As for the rest, he was left 'scratching his head'.

 

[Mr Chibs]

Shlepp & Kovac

 

[crystal ball]

To keep within volt drop rules with 2.5 mm² cable with a 25 amp MCB one is limited to around 25 meters, with same 2.5 mm² looking at 106 meters for a ring, so often you can't simply turn a ring final into two radials, and comply with volt drop.

7/0.029 is larger than 2.5 mm² so when the ring final was designed, with 30 amp fuse, even if the ring final was broken the overload was a lot less, and we should not have to plan for people fiddling and getting it wrong, the loop impedance tests every years should highlight any errors.

But to use radials means you really need 4 mm² cable so not a retro change. And I have found just as many 4 mm² radials where the person working on it clearly thought it was a ring and extended with 2.5 mm² as I have ring finals which have been broken, and broken ring is easy identified when testing, having a length of 2.5 mm² in the radial is harder to find.

But if we consider three 2.5 mm² radials can replace a ring final, then a home with three ring finals, then a 10 way consumer unit needs changing for a 16 way, with a cost of 6 extra RCBO's so the price is likely £70 more than with a ring final, which may be chicken feed with a re-wire, but on a new build home these pennies count.

Likely the kitchen is where ring final and radial will be most felt, if we follow the appendix and any appliance over 2 kW has dedicated feed great, but we don't, so a 32 amp ring with dish washer, tumble drier, and washing machine will hold in even with the odd boiling of a kettle. But that is not the case with 16 amp radials. So with radials you will need those dedicated feeds, so 6 RCBO's just for the kitchen.

I already have 16 RCBO's in this house, with his ideas with dedicated supply as appendix says, going to around 26 RCBO's not that I could do that as would also involve lifting floors, but if he wants radials he should leave the UK simple.

A bit drastic, going into exile because he installs radials, its year since I installed a RFC, somehow the ROW manages without them ( with a few exceptions)

 

[sparkwright]

I like rings because if there is one unregonised break in the earth wires, at least all the sockets will still have an earth.

I like the idea that if a ring should get a damaged cable that can't be mended easily, the ring can be made into two separate 20 amp radial circuits.

I like the idea of a ring being rated to 30/32 amps without having to use 4mm2 cable.

As much as I like the idea of a 30/32 amp radial in 4mm2, it means using more expensive cable.

People have commented how pleasant it is to work with 4mm2 cable - perhaps if 2.5mm2 was readily available as stranded T+E that would be better.

 

[EFLImpudence]

In tandem with your other thread:

I like rings because if there is one unregonised break in the earth wires, at least all the sockets will still have an earth.

Yes, but an unrecognised break in a live conductor is more serious.

I like the idea that if a ring should get a damaged cable that can't be mended easily, the ring can be made into two separate 20 amp radial circuits.

Yes, but why not do that in the first place - with 25A?

I like the idea of a ring being rated to 30/32 amps without having to use 4mm2 cable.

Ok, but not really a valid reason - you are, in effect using 5mm².
Do you feel the same for cooker circuits which could be 4mm² but 'everyone' still uses 6mm²?

As much as I like the idea of a 30/32 amp radial in 4mm2, it means using more expensive cable.

That depends on the routing of the cable.
Both legs of the ring in the same place or just running back from the farthest socket can negate the extra cost.

People have commented how pleasant it is to work with 4mm2 cable

It is much nicer.

perhaps if 2.5mm2 was readily available as stranded T+E that would be better.

W e l l , y e s , but...

 

[sparkwright]

This isn't really in tandem with my other post.

If a ring gets broken, it can be made into two 20 (or even 25) amp radials.

The question was - why not do that in the first place.

If one of these two radials got an unseen break in one of them, I can't convert them in the same way I could a ring. I'd have to run a new cable or make some damage.

 

[ericmark]

If any installation is not tested in years and years there are likely to be faults, be it radial or ring final, because people don't regularly test, that is no reason not to use a ring final.

 

[bernardgreen]

who is Slep?

He or she is mentioned a few times in the video

 

[EFLImpudence]

If a ring gets broken, it can be made into two 20 (or even 25) amp radials.

That's not a reason for installing a ring in the first place.

The question was - why not do that in the first place.

I asked that.

If one of these two radials got an unseen break in one of them, I can't convert them in the same way I could a ring. I'd have to run a new cable or make some damage.

The same as any other circuit.


The ring is a left-over from BS3036 30A fuses which require (or the equivalent of) 2.5mm² cable (with its CCC of 27A) for a circuit which must have a cable with a minimum CCC of 20A.
If the regulation were not still written for a BS3036 30A fuse but updated for MCBs, then you could have a ring of 32A/1.5mm² or 40A/2.5mm².