Correct me if I'm wrong, I thought that Arc fault detection devices were required for each individual final circuit. This seems like a poorly thought through addition to the electrical industry.
So it seems an advisary specification at present, a little like white road marking lines to provide disabled parking spaces.
I spoke to Wylex earlier this year, the double pole RCBOs that are compatible with the arc fault devices cannot be used in a three phase board as they do not have phase barriers.
So I suggest that you forget the idea of installing AFD to a three phase board and install a single phase sub-distribution board with the combined RCBO AFD devices in it for each of the final circuits.
