Dec 14 2017 13:30
"Would it be fair to say that a USB charger module added to a socket outlet is a fixed wired appliance and therefore not part of the installation wiring?"
No, it's not an appliance (as defined in the Act). From an ESRs perspective, t's a fitting connected to installation wiring. From a Wiring rules perspective, it's in the nature of an electricity converter ( LV > ELV, ac > dc), but could also arguably be classed as a kind of ELV socket outlet.
"Replacing a GPO on a non-RCD circuit with a GPO that includes a USB charger doesn't trigger the requirement to add RCD protection."
As far as 188.8.131.52 goes, yes Exception 1 applies: replacing an existing socket outlet with another socket outlet; specifically permitting replacement of single with multiple - and by implication also for double to quad, double to single, or any type to one including an ELV socket.
But add the USB on a separate plate, no longer a replacement; but instead an alteration to the subcircuit (adding a point). Unfortunately 2.6 doesn't differentiate between LV & ELV sockets when it comes to RCD protection, so RCD required.
Nor does 1.4.86 definition of socket outlet.
Not the only problem with 2.6. 184.108.40.206 doesn't allow a socket added to an NZ non-domestic (non-school) to avoid RCD - 220.127.116.11 doesn't require RCD for new subcircuits outside of schools, so there's no exception to pick up via 18.104.22.168.
Next edition is better, but in my view still not fully correct.