Screwfix have a BG 12 module CU with 6 RCBOs on offer for £69.99. At that price it is a steal so I am thinking of getting 2, one for the main house CU and I know it is overkill but one for the garage. I do want discrimination in the garage with 2 lighting circuits one for the main garage/workshop and one for the separated mancave, likewise 2 ring mains and all the outside lights will also be run off the garage CU.

The question is connecting the garage CU to the house CU? In the 17th edition wiki article the CU arrangement for a fully RCBO populated CU shows an MCB being used for the garage using SWA. In my case that will not be possible as the cable between CUs will be T&E with approx. 2m run in a wall chase. Is there any reason why the garage circuit cannot be protected by an RCBO at the house CU even though there will be further RCBOs for the separate garage/Mancave circuits?

Richard