US Patent 7740503 Current non-interruption bulb socket of lamp string

A lamp string includes first and second wires and a number of lighting units each including a socket receiving a bulb in electrical connection with the wires. The socket includes a husk, which is coupled to the wires and defines a cavity that receives and retains the bulb in such a way to establish electrical connections respectively between first and second contacts of the bulb and the first and second wires, and a plug, which is removably received in the cavity between the bulb and the husk and forms a bore that receives a current bypass device therein. The current bypass device has first and second conductors that are respectively set in electrical connection with the first and second wires. The bore has only an open end to ensure properly installing the current bypass device in the plug.