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The Carter system, also known as the Chicago system, was a method of wiring three-way switches in the era of early knob-and-tube wiring. This now-obsolete wiring method has been prohibited by the USA National Electrical Code since 1923, [ 2 ] even in new knob-and-tube installations which are still permitted under certain circumstances.
Leviton was founded in 1906 by Russian immigrants Evser Leviton and his son Isidor Leviton when they began manufacturing brass mantle tips for natural gas lights in Manhattan's Lower East Side. [ 2 ] [ 3 ] [ 4 ] In 1910, Isidor designed a screw-in lampholder for the newly invented electric light bulb and within ten years the lampholders were ...
Manufacturers introduce various new forms and styles, but for the most part decoration and fashion concerns are limited to the face-plates or wall-plates. Even the "modern" dimmer switch with knob is at least forty years old, and in even the newest construction the familiar toggle and rocker switch formats predominate.
Compared to a rheostat-based circuit, the use of a thyristor greatly increases efficiency, as far less waste heat is generated. Dimming lights with a solid state dimmer also reduces total power draw, unlike rheostat dimmers. Spira's design (and most modern dimmers) rely on the use of AC power, and on the characteristics of incandescent lights.
When the dimmer is at 50% power, the switches are switching their highest voltage (>325 V in Europe) and the sudden surge of power causes the coils on the inductor to move, creating a buzzing sound associated with some types of dimmer; this same effect can be heard in the filaments of the incandescent lamps as "singing". The suppression ...