Prefabricated connector systems and prefabricated system components for electrical installation applications used in connection with building services systems, the prefabricated system components comprising switching devices, EIB switching devices, actuators, coding switches, switch connections, EIB M modules and EIB M2 modules, expansion modules, extension modules, EIB tool software, mounting rails, cables, flat cables, distribution boards, sub-distribution boards, junction boxes, terminal boxes, distribution boxes, distribution blocks, distribution block T-connectors, combination connectors, combination distribution blocks, three-phase [a;c;] *ac * wiring, socket-outlet connections, installation bus wiring, flat cable adapters, prefabricated cables, extension cables, connection cables, cable assemblies, cable ferrules, male and female connectors, extender leads, starter leads, connection leads, intermediate couplings, mounting plates, TT connectors, spring-loaded connections, screw connections, fused extension leads, fused connection leads, fused distribution blocks, intermediate couplers, cable clips, cable end caps, system socket outlets, locking devices for free cable connection, locking devices for soldered components, and interlocking slides for snap-in connectors and for distribution blocks for retrofitting