1. A remote switch device comprising:a first port and a second port, one of which is to be coupled to a first power circuit through an external switch when the external switch conducts, and the other one of which is to be coupled to the first power circuit;
a third port to be coupled to a second power circuit through a load;
a switch unit including a first switch module coupled to said second port; and a second switch module coupled to said first port, said third port and said first switch module;
a wireless module configured to receive a wireless control signal that indicates a switching operation, and to output a switching signal according to the wireless control signal; and
a control unit coupled to said wireless module for receiving the switching signal, coupled to at least said second switch module for controlling switching operation thereof, and configured to detect a state of the external switch;
wherein, when said remote switch device is in a first operation state, said control unit controls said switch unit to switch, upon any one of receipt of the switching signal and detection of switching of the external switch, from one of a conducting state and a non-conducting state to the other one of the conducting state and the non-conducting state;
wherein, in the conducting state, said switch unit is controlled by said control unit to permit transmission of electrical power between the first and second power circuits through said first and second switch modules and the load; and
wherein, in the non-conducting state, said switch unit is controlled by said control unit to not permit transmission of electrical power between the first and second power circuits therethrough.