Patent ID: 8174805

Claim:
A residual current device for an electricity supply, the device comprising: a housing having an opening extending between opposite substantially parallel sidewalls of the housing, a current transformer inside the housing, the transformer comprising an apertured core disposed between and generally parallel to the sidewalls, the opening in the housing passing through the core, at least one load conductor inside the housing connected in series between the supply and a load and including a set of contacts by which an electrical connection between the supply and the load may be made or broken, the at least one load conductor passing through the core inside the housing between the inside diameter of the core and the opening so as not to be exposed externally of the housing, at least one further load conductor outside the housing and passing through the apertured core via the opening in the housing, the current transformer being responsive to the currents in the load conductors passing through the core to produce an output in response to a non-zero vector sum of said currents, and circuit means inside the housing and responsive to the output of the sensor to open the contacts if the non-zero vector sum of currents meets predetermined criteria as to amplitude and/or duration.