Normally used in bathroom / toilet locations. This model incorporates a built in humidity (condensation) sensor. When condensation is detected the fan switches on automatically. When the condensation level drops below the threshold the fan runs on for the pre-set timer period then switches off. Can also be wired to work in conjunction with the room light switch, when the light is switched on the fan comes on, when the light is switched off the fan runs on for the pre-set period. Requires permanent live, switched live and neutral connections for timer option to function (3 wires, excluding earth). The switched live connection can be omitted if only humidistat running is required. This fan must be connected to a permanently live supply and not routinely switched on / off. Additionally there is a pull-cord switch to manually switch the fan on. When switched off the fan reverts to humidistat function.