Abstract: An overload circuit breaker has a housing and a tripping device supported in the housing and having a helically wound, current-carrying bimetal strip composed of two face-to-face arranged metal components situated, respectively, at the inside and at the outside of the bimetal strip. The bimetal strip has a tripping portion which executes a tripping motion as the bimetal strip undergoes deformation under the effect of heat generated by an excess current flowing through the bimetal strip. The bimetal strip is formed of two electrically serially connected, oppositely wound bimetal helices each having an outer end constituting the opposite ends of the bimetal strip. The bimetal strip is affixed to the housing at both of its opposite ends. Further, the bimetal helices each have an inner end connected to one another by a coupling part. The coupling part constitutes the tripping portion of the bimetal strip.

Abstract: A multipole excess current switch composed of a plurality of single pole excess current switches each arranged to be placed in series in a respective circuit to be protected, each single pole switch including a U-shaped bimetallic member connected to conduct the current through such circuit and to undergo a change in shape when conducting an excess current, and a spring loaded switching arrangement arranged to open the switch in response to movement of the bimetallic member, and the switching arrangements of all of the single pole switches being mechanically connected to trigger operation of the spring loaded switching arrangements of the other single pole switches when one of the switches opens in response to an excess current through its associated circuit.