He invented a version of the light-dimmer switch for use in homes around the United States and led his Lutron Electronics Company into the production of lighting controllers.
Spira successfully implemented a design using thyristors, solid-state semiconductors small enough to fit into the wall box that housed a standard light switch.
Thyristor based designs (compared to rheostats) instead "chop" the incoming AC mains waveform, quickly switching their level of conductance (and the attached lights' brightness).
[6] On the basis of the dimmer alone, he and his wife Ruth Rodale Spira, who was an active associate, founded the Lutron Electronics Company in Coopersburg, Pennsylvania, in 1961.
The privately held firm, whose headquarters remain there today, has grown into an international manufacturer and distributor not only of dimmers, but also of motorized and automated window-covering systems, as well as lighting fixtures and temperature controls.