I think that evolved from a shortage of copper in the UK after WWII, and we moved from a radial wiring system to our now familiar ring main system.
It did indeed. It's also got a major (dangerous) flaw in that if the ring is broken (e.g. due to a cack handed electrician or DIY job) you can have an excess load on half of it which is not protected by the 30/32A fuse/breaker, and the problem isn't visible until things start overheating. 20A radials are much more sensible and I think new houses are moving that way.
It did indeed. It's also got a major (dangerous) flaw in that if the ring is broken (e.g. due to a cack handed electrician or DIY job) you can have an excess load on half of it which is not protected by the 30/32A fuse/breaker, and the problem isn't visible until things start overheating. 20A radials are much more sensible and I think new houses are moving that way.
Edit: FWIW, I suspect the number of fires caused by this is quite low because almost all household appliances these days are very low-power, in particular the use of electric heaters is very low because people tend to have gas central heating. I suspect the draw on an average socket circuit is well below 5A even with most things on. Similarly LED lighting (though that tends to be radials anyway) reduces the draw substantially - the current draw on my lighting circuit (6A breaker) is something like 0.6A with everything switched on. Only really the kettle, vacuum cleaner, toaster and hairdryer really tax it, and who has more than two of those on at once?
Washing machine and tumble drier?
Cookers and immersion heaters get their own circuits, don't they?
20A radials can cause you issues with large appliances however.It did indeed. It's also got a major (dangerous) flaw in that if the ring is broken (e.g. due to a cack handed electrician or DIY job) you can have an excess load on half of it which is not protected by the 30/32A fuse/breaker, and the problem isn't visible until things start overheating. 20A radials are much more sensible and I think new houses are moving that way.
Toaster and a kettle being on at once is hardly unusual.......Edit: FWIW, I suspect the number of fires caused by this is quite low because almost all household appliances these days are very low-power, in particular the use of electric heaters is very low because people tend to have gas central heating. I suspect the draw on an average socket circuit is well below 5A even with most things on. Similarly LED lighting (though that tends to be radials anyway) reduces the draw substantially - the current draw on my lighting circuit (6A breaker) is something like 0.6A with everything switched on. Only really the kettle, vacuum cleaner, toaster and hairdryer really tax it, and who has more than two of those on at once?
The difference being that with a radial, the CB will trip when it is overloaded, whereas with a broken ring the cable can be seriously overloaded without the CB tripping. Toasters and kettles both tend to be plugged into much the same part of the ring (in the kitchen) and are therefore both likely to be on the same side of any break.20A radials can cause you issues with large appliances however.
32A means you basically never have to worry about overloading a circuit, since even 2 full 13A appliances won't do it.
Toaster and a kettle being on at once is hardly unusual.......
Well modern practice is often to provide a seperate ring main, solely for use in the Kitchen.The difference being that with a radial, the CB will trip when it is overloaded, whereas with a broken ring the cable can be seriously overloaded without the CB tripping. Toasters and kettles both tend to be plugged into much the same part of the ring (in the kitchen) and are therefore both likely to be on the same side of any break.
I'm not really sure how you can detect a broken ring easily, it is likely to require something more sophisticated than the electrics present in a normal RCD or RCBO.T
In my house, the ring has its own dedicated RCCB. It surely shouldn't be that difficult to design an RCCB that incorporates broken-ring detection. That such things aren't available is I suspect due to there being such a small potential market for them, the UK and Eire being the only European countries I am aware of to use rings.
A substantial imbalance in the current being fed into the two sides of the ring. Same principle as detecting an imbalance between current in live and neutral legs of a circuit. Agreed it would be more expensive to provide the extra functionality, but the greatest expense would be down to the fact that because they would only be used in the UK, there would be so few sold to recoup the initial investment.I'm not really sure how you can detect a broken ring easily, it is likely to require something more sophisticated than the electrics present in a normal RCD or RCBO. It'l be substantially more expensive.
20A radials can cause you issues with large appliances however.
32A means you basically never have to worry about overloading a circuit, since even 2 full 13A appliances won't do it.
Toaster and a kettle being on at once is hardly unusual.......
I'm not really sure how you can detect a broken ring easily, it is likely to require something more sophisticated than the electrics present in a normal RCD or RCBO.
It'l be substantially more expensive.
Some early rings were made out pairs of 15A radials, and were fed through pairs of 15A fuses, one to each leg.The easiest way is to lop the ring in half and wire each half to a separate breaker, making each a 15 or 20A radial. Though that only works if the ring isn't too "long".
You don't actually need to physically break the ring, it can be done quite easily using cheap digital signal processing using the same method as track circuits in electrified areas. Inject a RF signal into each half of the ring and trip the breaker if you can't see the signal coming back on the other side of the ring.The easiest way is to lop the ring in half and wire each half to a separate breaker, making each a 15 or 20A radial. Though that only works if the ring isn't too "long".
It did indeed. It's also got a major (dangerous) flaw in that if the ring is broken (e.g. due to a cack handed electrician or DIY job) you can have an excess load on half of it which is not protected by the 30/32A fuse/breaker, and the problem isn't visible until things start overheating. 20A radials are much more sensible and I think new houses are moving that way.
Edit: FWIW, I suspect the number of fires caused by this is quite low because almost all household appliances these days are very low-power, in particular the use of electric heaters is very low because people tend to have gas central heating. I suspect the draw on an average socket circuit is well below 5A even with most things on. Similarly LED lighting (though that tends to be radials anyway) reduces the draw substantially - the current draw on my lighting circuit (6A breaker) is something like 0.6A with everything switched on. Only really the kettle, vacuum cleaner, toaster and hairdryer really tax it, and who has more than two of those on at once?
Do you not have an electric oven or hob? These draw quite a lot of electricity.
Edit: FWIW, I suspect the number of fires caused by this is quite low because almost all household appliances these days are very low-power, in particular the use of electric heaters is very low because people tend to have gas central heating.
Plus the fact that relatively few rings out of the total installed are either broken in their lifetime or installed without testing. Yes I know that there are cowboys out there but the type of faults that they 'install' tend to be more like poor insulation within terminating accessories, e.g. lack of sleeving, and poor wire dressing. With 30/32A ring circuits having been around for over 70 years, almost every one of them has had at least some attention from a competent electrician evwen if they are still in use. The recommended life of a ring circuit was originally stated as 25 years, partly becuse early ring circuits were vulcanised rubbber insulated, (VRI). Those recommendations have not changed since PVC sheathed become the norm, but 2.5mm twin and earth cables are continuously rated for 32A when surface mounted, (or under floorboards etc.) and 26A when enclosed in conduit in a thermally insulating wall. The chances of continuous operation of 6kW on a ring circuit in a domestic environment are very rare, and unlikely to coincide with a poor wiring job. That is why domestic circuits diversity allowances whereas commercial/industrial ones don't. It would be impractical to prevent every cowboy malpractice, - as each new safeguard was introduced, they would devise new ways to subvert those 'inconveniences', - some of those new dodges could well be more dangerous than the original practices that the safeguards were designed to prevent.A substantial imbalance in the current being fed into the two sides of the ring. Same principle as detecting an imbalance between current in live and neutral legs of a circuit. Agreed it would be more expensive to provide the extra functionality, but the greatest expense would be down to the fact that because they would only be used in the UK, there would be so few sold to recoup the initial investment.
Ovens and hobs have a dedicated radial circuit and are not generally connected to the main socket ring.
Usually true for floor-standing cookers (which often have two ovens and a hob), but many houses have built-in electric ovens which run off a 13amp plug.
https://markselectrical.co.uk/elect...single-built-in-electric-ovens&attributes=125