Which Consumer Unit?

[GaryMo]

Using dual RCD boards you would be limiting disruption:

RCD 1
Sockets Downstairs
Lights Upstairs

RCD 2
Sockets Upstairs
Lights Downstairs

If one of the RCD's should trip and not reset due to a N-E fault then you would have provision for lighting on either floor via lights themselves or table lamps via sockets.

As you say though, RCBO's improve it even further.

 

[Spark123]

Knowing my luck it will be the down sockets and the up lights including the bathroom!

 

[GaryMo]

Knowing my luck it will be the down sockets and the up lights including the bathroom!

Your luck sounds like mine - have a 50/50 chance of a motor running the right way, normally get it wrong so change my mind when terminating and still get it wrong!

 

[Spark123]

I got no chance, of two buildings I normally work in the phase rotation is opposite!