Patent ID: 7227756

Claim:
A power supply keying method for use with an electrical apparatus, comprising: defining a plurality of power supply classes, each power supply class of said plurality of power supply classes having different power supply electrical characteristics from power supply electrical characteristics of other of said plurality of power supply classes; associating with said plurality of power supply classes a plurality of power supplies, each of said plurality of power supplies including a power supply housing having a unique keying arrangement corresponding to one power supply class of said plurality of power supply classes; and providing in said electrical apparatus a power supply receptacle for receiving at least one power supply of said plurality of power supplies, said unique keying arrangement of said power supply housing in conjunction with said power supply receptacle permitting reception of a particular power supply of said plurality of power supplies into said power supply receptacle only if said power supply class associated with said particular power supply has power supply electrical characteristics that satisfy electrical power requirements of said electrical apparatus.