New single module AFDD RCBO

I would be interested in forum members views on whether AFDD protection is needed on 30mA RCD protected circuits where the CPC is in close contact with the insulation on the live conductors such as T &E and FP200 cables? Would not the 30mA RCD operate far in advance of an AFDD if there was thermal damage to the conductor insulation?

Way back when AFDs were yet to be mandated in the states at least one US commentator considered the European wiring not to really need them, but US wiring to be more vulnerable to sizzling faults due to what we would recognise as an excessive loop impedance given the lower voltage.

Interestingly at the time the argument he was making was not for a dedicated AFD with complex electronics, but for US circuit breakers to be specified to behave more like our B and C types.

Scan of the article is attached.

The question of T and E is germane, almost any sort of damage other than a series break - which is likely to be noticed by the user as the load will flicker, will give a something to earth fault once it gets hot.  In any case on 230V a short L-N is likely to either blow clear or fire the MCB in the normal way.


Oddly I have seen it suggested that we should change T and E and put the live core in the middle and N and E outside to reduce nail strikes, but I think this  is based on rather flakey logic.