I'd be far happier if it said "double or reinforced insulation is required for all wiring not protected by an RCD or RCBO"
It does not.
In a way the wider regs do - we need to apply (at least) one of the methods in chapter 41 to achieve protection against electric shock under fault conditions - where ADS (411) cannot work then obviously we need to use one of the other methods instead. 413 Electrical separation isn't feasible with an earthed supply, 414 SELV/PELV can't apply to a LV system, none of the 418 methods can be used in a domestic situation, 419 doesn't seem like much help - so what's left other than 412 Double/Reinforced insulation? There's nothing special about CUs or any upstream accessories - it's just the normal rules.
I'd be far happier if it said "double or reinforced insulation is required for all wiring not protected by an RCD or RCBO"
It does not.
In a way the wider regs do - we need to apply (at least) one of the methods in chapter 41 to achieve protection against electric shock under fault conditions - where ADS (411) cannot work then obviously we need to use one of the other methods instead. 413 Electrical separation isn't feasible with an earthed supply, 414 SELV/PELV can't apply to a LV system, none of the 418 methods can be used in a domestic situation, 419 doesn't seem like much help - so what's left other than 412 Double/Reinforced insulation? There's nothing special about CUs or any upstream accessories - it's just the normal rules.
