The reasoning was [and is]- how many folks will draw more than the allowed 30A on a 230v circuit? We don't have 120v POCO supply in Britain, nor 3-phase in domestic premises. A broken ring hot is a rare event, but could cause overheating problems in extremes. It was allowed after WWII because we were busted but had to rebuild after 5 years of bombing, using the least amount of copper. The system is definitely out of date, considering modern heavy use of electricity, and some UK builders do use 20A spurs now as an alternative. The ringmain is usually restricted to separate ring[s] per floor area of no more than 1000 sq feet, not the whole dwelling on just one ring. Most sockets actually run lowpower stuff like bedside lights, food mixers, a vacuum cleaner [drawing maybe 4A], or a toaster. The tv/DVD etc might pull 2A. Electric kettle 12A max if 3000W. That leaves portable electric fires, which are usually drawing 4-12A. If you are running 6kw of freestanding electric fires at today's energy costs, you are certifiably
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