MCB discrimination ...

[jackhammerJIM]

63B-6B has FD up to approx 250amps

This is not useful given the max zs for a b63 is 0.55 ohms

230 / 0.55
= 418 amps

 

[Darkwood]

Just looked them up in my Schneider books for a standard C60 mcb - mcb discrimination. The values in post 17 are a tad out but were done from memory

63b - 6b is 250amps as I stated (I agree this is a pointless value given max zs but was just showing the relative fault levels)
63c - 6b is 500amps
63d - 6d is 1200amps

I actually see mcb 60898 cascading in industrial and commercial all the time, like I said I wouldn't ever do this as a 60amp BS88-II would provide full discrimination for the lower end mcb's and partial if higher assuming supply size is limited, 60898 are prone to filament lamps nuisance tripping where any BS88 are not do to the nature of operation. (on a plus, filament lamps are now not as common).