An interface module in an electrical switch box mounted on a wall for replacing a light switch assembly, the electrical switch box including an input wire coupled to a power source, an output wire (18, 218) coupled to a first lighting device, and a pair of threaded bores (34, 234), the interface module comprising: 1.1 a first housing (74, 274) located within the electrical switch box with the light switch assembly removed from the electrical switch box; 1.2 a first terminal mounted on the first housing (74, 274) and configured to connect to the input wire; 1.3 a second terminal mounted on the first housing (74, 274) and configured to connect to the output wire (18, 218); 1.4 a first switch component positioned within the first housing (74, 274), the first switch component being coupled to the first housing (74, 274) between the first terminal and the second terminal and configured to activate and deactivate the first lighting device when the second terminal is connected to the output wire (18, 218); 1.5 a second housing, 1.6 a user interface configured to receive operating power from the power source through the first terminal when the first terminal is connected to the input wire, wherein the user interface is mounted on the second housing; characterized by: 1.7 a switch control configured to alter a state of the first switch component, wherein the switch control is included in the user interface; 1.8 a wireless transmitter coupled to the user interface and positioned within the second housing, wherein the wireless transmitter is configured to wirelessly transmit signals indicative of inputs received through the user interface to one or more external devices; 1.9 a user interface connector mounted on the second housing and coupled to the user interface; 1.10 an accessory connector protruding outwardly from a side surface of the first housing that is coupleable to the user interface connector, such that electrical coupling between the first housing and the second housing is hidden within interior of the wall, 1.11 wherein the wireless transmitter and user interface are configured to receive power from the input wire through the first housing, the accessory connector, the user interface connector and the second housing, and 1.12 wherein the user interface is used as a security code input device for a building's security system and the one or more external devices includes a security system. 1.1 a first housing (74, 274) located within the electrical switch box with the light switch assembly removed from the electrical switch box; 1.2 a first terminal mounted on the first housing (74, 274) and configured to connect to the input wire; 1.3 a second terminal mounted on the first housing (74, 274) and configured to connect to the output wire (18, 218); 1.4 a first switch component positioned within the first housing (74, 274), the first switch component being coupled to the first housing (74, 274) between the first terminal and the second terminal and configured to activate and deactivate the first lighting device when the second terminal is connected to the output wire (18, 218); 1.5 a second housing, 1.6 a user interface configured to receive operating power from the power source through the first terminal when the first terminal is connected to the input wire, wherein the user interface is mounted on the second housing; characterized by: 1.7 a switch control configured to alter a state of the first switch component, wherein the switch control is included in the user interface; 1.8 a wireless transmitter coupled to the user interface and positioned within the second housing, wherein the wireless transmitter is configured to wirelessly transmit signals indicative of inputs received through the user interface to one or more external devices; 1.9 a user interface connector mounted on the second housing and coupled to the user interface; 1.10 an accessory connector protruding outwardly from a side surface of the first housing that is coupleable to the user interface connector, such that electrical coupling between the first housing and the second housing is hidden within interior of the wall, 1.11 wherein the wireless transmitter and user interface are configured to receive power from the input wire through the first housing, the accessory connector, the user interface connector and the second housing, and 1.12 wherein the user interface is used as a security code input device for a building's security system and the one or more external devices includes a security system.