Regulators recommend that each circuit should have its own RCD safety switch. There could be one for lighting, another for hot water, etc. So when a trip occurs, you can determine its cause, which helps you resolve the issue sooner. RCBO breaker installation is also recommended on all power outlet circuits to ensure power comes from two separate zones (electricity supplies) instead of one source like traditional circuit breakers. In accordance with the Electricity Regulations 1947, residential properties for sale or rental must have at least two RCDs. There can not be more than three of these circuits on any one circuit breaker, and lighting switches must be divided evenly between them, with no less than half being attached to each protection device.