A safety system receives inputs from safety related input devices such as smoke detectors and the like and provides triggering outputs to notification appliances such as bells and the like and/or safety functions such as door releases. To facilitate testing of the input devices the system incorporates a timer operative to disconnect the output devices for a period of time during which testing may be achieved, automatically reconnects the output devices at the end of the time, records the number of triggering outputs received at the outputs during that period.