Mains 230/240V AC 50Hz. Extraction rate 21 litres per second, 75 cubic metres per hour. Easy to install and suitable for wall or ceiling mounting. This model is for operation with the room light switch. When the light is switched on the fan comes on, when the light is switched off the fan continues to run for a pre-set time. Requires permanent live, switched live and neutral (3 wires excluding earth) at the fan position in order to operate correctly. Please note that the timer function cannot be used unless you have these three wires to connect.