Abstract: A thermally-responsive switch, designed to go open circuit in response to relatively low overload currents of the order of 2 amps and below, comprises a moulded plastics body capturing therein first and second simple copper wire terminals and having an internal chamber wherein a snap-acting bimetal blade of very low thickness is spot-welded to one of the wire terminals and carries a silver contact which co-operates in switching operations with the other wire terminal, the internal construction of the switch body chamber being arranged to provide physical support to the bimetal blade by way of the respective one of the wire terminals to which the bimetal blade is secured.