Ring mains of this type are rare outside the UK. It is used in British influenced countries (including Ireland is influenced by the Brits).
Ring mains for distribution of power (in the street, on poles etc.) has found use in other places too, but I don't know how common it is. It makes a lot of econmical sense, since you can make long cable runs with limited voltage drop in the case of moving loads. Ehhh... Let me rephrase that: If you have a bunch of houses, the odds are that the cooker and the water heater is only on in a couple of houses at the same time. Then a ring is great.
The British plug and socket and ring final circuit system has proven itself over many years. Its development was due to the recognition of an opportunity seen by leaders during a time of war and mass destruction. A truly unique, innovative, world class system was developed by people of vision. A system that cannot be equalled in terms of safety, performance and convenience.
Re: Ring Main Circuits#145849 07/28/0610:13 AM07/28/0610:13 AM
Good call C-H, While the NZ block system here could be called a Ring Main,it is a 3 phase one, fused at every "take-off" point at single phase or 3 phases, depending upon the load. As I've said before here, the real use for Ring Mains in NZ are for Caravan Parks. With Neutral-Screened cables and an RCD at each socket on the system and an earth electrode at every 2nd or third box, (depending on the size of the park). Things are a Faultsman's worst nightmare, drunken tourists with no power. Worst ones are Kiwi's from just down the bloody road, that wanted to try out their new campervan.
Re: Ring Main Circuits#145850 07/29/0605:47 AM07/29/0605:47 AM
my Iron recently had a short circuit. The 16A MCB tripped and the RCD tripped very quickly. The BS1363 fuse remained fully intact.
More worryingly, I've seen the same happen with 20A diazed fuses. i.e. there was an overcurrent fault on a kettle and the plug fuse remained intact while the 20A diazed popped.
You more or less expect an MCB to trip before a BS1363 plug fuse on short circuit, considering the Time-Current Characteristic of MCB's. It takes time to heat up a piece of tinned copper wire (albeit short), the mechanism in the MCB works by magnetism caused by the fault current on the circuit, these are pretty much instant in their action. Also, with the diazed fuse, if they are anything like an HRC fuse, there are 7 strands of finer silver wire leading through tubes in the fuse body, this means that the fuse will blow at a lower aggregrate(sp?) fault current. It's also done like that to ensure the fuse runs cooler.
Re: Ring Main Circuits#145855 07/31/0606:08 AM07/31/0606:08 AM
All Diazed fuses I've ever taken apart (up to 25A) had a single strand of wire.
I guess the BS1363 fuses are more an overload protection than a short circuit protection. But then on the other hand they only make sense in the plugs of let's say outlet strips/multi taps. I always thought that system was less than ideal...
Re: Ring Main Circuits#145856 07/31/0608:40 AM07/31/0608:40 AM