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3-way lamp

A 3-way lamp, also known as a tri-light, is a lamp that uses a 3-way light bulb to produce three levels of light in a low-medium-high configuration. A 3-way lamp requires a 3-way bulb and socket, and a 3-way switch.

In 3-way incandescent light bulbs, each of the filaments operates at full voltage. So unlike incandescent bulbs controlled by a dimmer, the color of the light does not change between the three steps of light available.[citation needed] Lamp bulbs with dual carbon filaments were built as early as 1902 to allow adjustable lighting levels.[1]

Certain compact fluorescent lamp bulbs are designed to replace 3-way incandescent bulbs,[2] and have an extra contact and circuitry to bring about similar light level. In recent years, LED 3-way bulbs have become available as well.[3]

  1. ^ US 931807, "Incandescent Lamp" 
  2. ^ Matthews, Mike. "How a 3-Way CFL Switch Works". HomeGuides.SFGate.com. Hearst Newspapers. Retrieved March 21, 2022.
  3. ^ Lewis, Bill (December 19, 2022). Campbell, Larry (ed.). "What Is a 3-Way Light Bulb and Socket?". The Spruce. Retrieved January 7, 2023.