An RCBO (residual current circuit breaker with overload protection) combines the functions of a miniature circuit breaker (MCB) and a residual current device (RCD) in a single module. Upgrading individual circuits within a consumer unit to RCBOs means each circuit has its own independent fault and overload protection, reducing the likelihood that a fault on one circuit will interrupt others.
Shared upstream protection can still disconnect more than one circuit. In a consumer unit fitted with a split-load design, a single RCD protects a group of circuits.
If that RCD trips, all the circuits it covers lose power simultaneously. An RCBO-equipped board avoids this by giving each circuit independent protection, which reduces disruption and makes it easier to identify which circuit has developed a fault.
RCBO upgrades are commonly carried out when a property experiences nuisance tripping that affects multiple circuits at once, when a new circuit with a higher likelihood of earth faults is added such as an outdoor supply or EV charger, or when a householder wants to future-proof their installation before adding further electrical loads. An engineer will assess the existing consumer unit to establish whether it is compatible with RCBOs of the appropriate specification and type, and will carry out testing after installation to confirm the circuit and its protective devices are correctly installed and operating.
Notification depends on the scope and location: a new circuit, replacement consumer unit or qualifying work in a special location may be notifiable in England. Changing an existing protective device does not by itself mean the work is notifiable.
An engineer can advise on the specific requirements for your installation before work begins.