ID: 
2313
Maker's Name: 
Belling & Lee Ltd
Where made: 
England
Dimensions: 
3.5 × 3.5 × 1.2 cm

A bimetallic clip holds a spring-loaded wire. The clip is heated by a surrounding wire, which is in series with the circuit being monitored. When the current in the wire exceeds 250mA, the heat causes the bimetallic clip to open, releasing the wire and breaking the circuit. The breaker is reset by pushing the wire back into the clip manually.