Patent ID: 7049939

Claim:
A power line carrier system comprising: a power branch device including a power plug being removably connected to an in-house external power line, a plurality of power outlets, and a built-in power line for connecting the power plug and the power outlets; and at least one electric device configured to be plugged into one of the power outlets, and perform a power line communication in a first signal mode and a second signal mode, with another electric device, the first signal mode being for a power line communication between electric devices connected to the built-in power line, and the second signal mode being for a power line communication between an electric device connected to the built-in power line and an electric device not connected to the built-in power line via the in-house external power line, wherein the power branch device controls the power line communication to pass a power line carrier signal in the first signal mode only in the built-in power line, and allow a power line carrier signal in the second signal mode to pass in the in-house external power line.