Safety devices
First Claim
1. Hand-held electrical apparatus to be connected to a mains supply, including an electrical supply lead and a plug having supply pins, the apparatus having an electrical detector in the form of a conductive sensor adjacent to any exposed electrical part whereby if the apparatus becomes wet or damp the water will form a path of conduction between the exposed electrical part and the sensor, a conductive path from the sensor forming part of the supply lead to the plug, and the plug comprising a mechanical switch at least in a live line of the supply lead to the apparatus, the mechanical switch comprising a length of wire holding electrical contacts closed against the action of resilient means urging those contacts to an open position, control means connected to the sensor by the conductive path which will subject the wire to a high current when a path of conduction between an exposed electrical part and the sensor is established, whereby the wire will then break or lose its mechanical strength and so allow the mechanical switch to open, and a circuit board mounted so as to be movable within the plug between a closed position where at least one contact carried by said circuit board electrically engages a contact joined to at least one supply pin of the plug and an open position where those contacts are out of engagement so isolating at least the live line to the apparatus from the supply pin, the board being urged from its closed position to its open position by a spring, the length of wire holding the board in the closed position against the action of the spring and so releasing the board to move to its open position when subjected to a high current by the control means.
1 Assignment
0 Petitions
Accused Products
Abstract
Hand-held electrical apparatus having an electrical detector in the form of a conductive sensor adjacent to any exposed electrical part so that if the apparatus becomes wet or damp the water will form path of conduction between the exposed electrical part and the sensor. A conductive path from the sensor forming part of the supply lead to the plug, and the plug comprising normally closed mechanical switch at least in the live line from the mains supply to the supply lead to the apparatus and a control circuit connected to the said sensor by the conductive path which open the switch as a result of the conductive path having been formed from the exposed electrical part because of the presence of moisture. The switch comprises a length of wire holding electrical contacts closed against the action of a spring. The control circuit fuse the wire, however, to allow the spring to open the contacts when the conductive path is established. A circuit board is slidably mounted in the plug and carries one of the pair of electrical contacts and the components of the control circuit, the wire holding the circuit board against the action of the spring to keep the mechanical switch in its closed position.
139 Citations
13 Claims
- 1. Hand-held electrical apparatus to be connected to a mains supply, including an electrical supply lead and a plug having supply pins, the apparatus having an electrical detector in the form of a conductive sensor adjacent to any exposed electrical part whereby if the apparatus becomes wet or damp the water will form a path of conduction between the exposed electrical part and the sensor, a conductive path from the sensor forming part of the supply lead to the plug, and the plug comprising a mechanical switch at least in a live line of the supply lead to the apparatus, the mechanical switch comprising a length of wire holding electrical contacts closed against the action of resilient means urging those contacts to an open position, control means connected to the sensor by the conductive path which will subject the wire to a high current when a path of conduction between an exposed electrical part and the sensor is established, whereby the wire will then break or lose its mechanical strength and so allow the mechanical switch to open, and a circuit board mounted so as to be movable within the plug between a closed position where at least one contact carried by said circuit board electrically engages a contact joined to at least one supply pin of the plug and an open position where those contacts are out of engagement so isolating at least the live line to the apparatus from the supply pin, the board being urged from its closed position to its open position by a spring, the length of wire holding the board in the closed position against the action of the spring and so releasing the board to move to its open position when subjected to a high current by the control means.
Specification