The Usefulness of Bi-Level Switching

California's Title 24 Energy Efficiency Building Standard requires multiple lighting level control in all individual offices. Usually, this requirement is fulfilled using bi-level switching. With bi-level switching, each office occupant is provided with two wall switches near the doorway to control their lights. In a typical installation, one switch would control 1/3 of the fluorescent lamps in the ceiling lighting system, while the other switch would control the remaining 2/3 of the lamps. This allows four possible light levels: OFF, 1/3, 2/3 and FULL lighting.

Original Technical Note: November 1998. Revised August 1999