A control for engagement with the external base of a liquid heating vessel comprises a carrier mounting two bimetallic actuators at opposite ends thereof. The actuators operate at the same temperature. Attached to the carrier is a moulding which provides a cordless electrical connector for the vessel, as well as mounting switch means operable by the actuators through push rods. The push rod acts on a leaf spring to open the contacts, and upon further movement engages an arm of a trip lever, so tripping the lever and causing a further arm of the lever to engage the leaf spring open the contacts fully.