"17 edition"consumer units still being sold.

Perhaps I have to get an 18th edition (book) sometime ... what's the change about RCDs? Anything firm, or just a bit more stuff about making wise choices, being thoughtful, reading appliance manufacturers' demands on RCDs (what does the word "externality" mean in economics?), etc.   Perhaps there's no point in my little battle against the AC type!  A year and a half ago I was surprised at how hard it was to find a simple type A in the UK. Since then I've been noting how the ability to use type-AC "where appropriate" leads to their general use where not really appropriate, and how the price of A tends to be more in the UK than in countries where AC is not permitted.  I was working on writing something up about this, but perhaps I'm unaware of recent changes in the rules that would make this superfluous - although it doesn't look as if AC has gone down in popularity in terms of what the retailers offer.

Perhaps I have to get an 18th edition (book) sometime ... what's the change about RCDs? Anything firm, or just a bit more stuff about making wise choices, being thoughtful, reading appliance manufacturers' demands on RCDs (what does the word "externality" mean in economics?), etc.   Perhaps there's no point in my little battle against the AC type!  A year and a half ago I was surprised at how hard it was to find a simple type A in the UK. Since then I've been noting how the ability to use type-AC "where appropriate" leads to their general use where not really appropriate, and how the price of A tends to be more in the UK than in countries where AC is not permitted.  I was working on writing something up about this, but perhaps I'm unaware of recent changes in the rules that would make this superfluous - although it doesn't look as if AC has gone down in popularity in terms of what the retailers offer.