Trumpy, I think that requiring people to retrofit RCDs or GFCIs (depending where you live) to existing circuits would be a bureacratic nightmare, however as a matter of policy, if working on a consumer unit [switch board in your neck of the woods I believe?] I will generally fit one, they're cheap, a lot cheaper than a new life.
Sorry if all this is boring, but it's my pet subject just now.
Alan, not boring at all, one of the few places on the net you can have a sensible discussion about excrement <grin>.
People here in the UK tend to take city sewers for granted, and dump anything and everything down them, upto and including rubble, hazardous chemicals etc.
