A yaw sensor for a wind turbine comprises a plurality of rotary switches, each configured to be coupled to a yaw drive gearbox of a wind turbine nacelle, the rotary switches each being operable to activate and deactivate respective associated electrical contacts in dependence on an amount of yaw rotation of the nacelle relative to a start position.
Each electrical contact is active at a plurality of first yaw rotation ranges with respect to the start position, and inactive at a plurality of second yaw rotation ranges with respect to the start position, the first and second yaw rotation ranges being interleaved.