An RCBO is a combination of an MCB and RCD. This enables both over current protection and earth fault current protection within a single module. Terminal Capacity: 1P, 2P 6kA & 10kA Cable up to 16mm2, The single pole RCBO is the same width as an mcb (17.5mm) and can be retro-fitted in a consumer unit when the extra protection of an RCD is required.