Federal MCCB Data sheets

So I will stick with the 9IN and note it.
Very sensible - and if there is enough PSSC to clear the breaker, then all is well.  If there isn't then one cunning wheeze is to add an earth fault relay to the installation, but that really cocks up the discrimination with whatever is down stream. 
Realise that in the days of hot-wire fuses the 5 seconds thing was often a bit liberally interpreted - it makes very little difference to the danger if the fault curretn is too low and 5 seconds is actually 6 or 7. The magnetic MCB changed that attitude and means we now think about the voltage tolerances etc. as the go-no go for the fast trip slow trip is not that if the Zs is a bit high, 0.4 seconds becomes 0.5, rather it might not trip at all for 'ages' (some seconds) on that timescale.

Mike.