A circuit breaker is a strict set of restrictions that could be introduced for a fixed period of time, for example, a minimum of two weeks. It is designed to help slow down the spread of the coronavirus (COVID-19) in local communities.
A circuit breaker would include a ban on household mixing and non-essential travel as well as the closure of non-essential shops and hospitality. In Wales, a circuit breaker has been called a firebreak.
Circuit breaker should be lower case and two words.