A safety system has a sensor for detecting an alarm signal of a smoke alarm (10) and producing an interrupt signal (16) in response to the smoke alarm output. An interrupt device (18) is controlled by the interrupt signal (16) for interrupting the operation of a domestic appliance (20). This enables a standard smoke alarm to be fitted, and the output of the smoke alarm is used to trigger an interrupt device. This may interrupt electrical power (for example to an electric cooker) or a gas supply (for example to a gas cooker).
