Safety of Using Adiabatic Method?

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I'm thinking, and while I could be wrong, is the adiabatic method a possible latent safety hazard? As well as undersized CPCs on circuits 32 amps and under?

Normally DNO sources are strong with relatively high PFC, and we have a known Ze value. However, should someone bring a portable generation unit on site after an outage, or a large yet short circuit limited inverter (Tesla Power Ball), Ze values can be such that MCB opening time increases. Such an increase can overheat the CPC, up to the point of melting it.

From a touch voltage perspective I humbly do not see a major concern however, in that 20 x 10 = 200 amps, 1.15 ohms or 46kw- a 46kw load on a 25kw generator would result in a significant drop in the output voltage whereby 230 volts dropping to 110 volts giving 55 volts to remote earth such that a longer disconnection time will not result in organic bodily injury.

However, the risk of fire and shock from an overheating CPC is relevant.

What do others make of this point of view?

 

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Table 54.7 is the generic "half phase size, if that is above 16mm, or phase size" rule for cases then you can't use the adiabatic approach (for whatever reason, OCPD unknown or just too much trouble).

In itself is really just a relaxation of the fairly obvious case that is a cable has suitable protection for L-N fault/overload, then the same CPC is fine, and going L-E is (I would hope!) always a fault condition and not overload sort of durations so it can be relaxed a little.

Of course the TN-C-S "open PEN" fault is a clear exception to these assumption hence the additional regs in Table 54.8 that set a lower limit to CPC size so a 6mm (or below) sub-main cable needs additional CPC if bonding to extraneous conductive parts under these conditions.

Agree. The thing is, and its being argued in US forums, that Ze can change over time for several reasons and such device clearing time can change. With a full/half size CPC there is no worry of shock or fire should tripping time increase.