Electric apparatus for electric wiring installations, namely, switches, two-way switches, commutators, electric plugs and sockets, fuse-links and wire type fuses, holders for fuse-links, lampholders for filament and fluorescent lamps, electric bells and sound signaling devices, circuit breakers, low and medium power switches, mercury switches, solid state switches, motor operators and remote motor operators, distribution boards whether combinable or not, terminal blocks, junction boxes, connectors, terminal strips, indicator units, signal processors and circuit boards for signaling and warning, residual current relay, voltmeters, ammeters, wattmeters, electronic apparatus mountable as common electric wiring devices, namely, photo electric relays, thermostats, sunset switches, and limit switches, simple and bi-stable relays, timers and timer switches, light dimmers, earth leakage circuit breakers, thermomagnetic and earth leakage circuit breakers, small ganged circuit breakers which may be inserted in wiring device supports, small electric transformers, remote control switches, emergency relays, telephone sets, telephones, radio sets for locating personnel, loud speakers, television door audio speakers, videophones, closed-circuit television sets for civil and industrial use, electronic components, namely, transistors, resistors, capacitors and printed circuits