just for interest (perhaps) OCP for RCCBs

Well to admit, this rccb ocp specific detail without diversity allowance had escaped me.

It does seem to be, for dual+ RCD boards, that

• sum up the MCBs and ensure ≤=  RCD rating, or
• ensure the RCD rating is ≥= OCPD protecting it/the board, or
• check that the manufacturer is ok with the RCD OCPD combo if above not met

is the order of the day, or something like that .

Or just use all RCBO  ;-)

18th Edition updates:

BS7671 (536.4.202)

However, overload protection shall not solely be based on the use of diversity factors of the downstream circuits.

To achieve overload protection of RCCBs or switches, the rated current of the OCPD shall be selected according to the manufacturer's instructions.

Well to admit, this rccb ocp specific detail without diversity allowance had escaped me.

It does seem to be, for dual+ RCD boards, that

• sum up the MCBs and ensure ≤=  RCD rating, or
• ensure the RCD rating is ≥= OCPD protecting it/the board, or
• check that the manufacturer is ok with the RCD OCPD combo if above not met

is the order of the day, or something like that .

Or just use all RCBO  ;-)

18th Edition updates:

BS7671 (536.4.202)

However, overload protection shall not solely be based on the use of diversity factors of the downstream circuits.

To achieve overload protection of RCCBs or switches, the rated current of the OCPD shall be selected according to the manufacturer's instructions.