Residential Lighting

Economic Worksheet: Table 1
Table 1. Power Reduction Factors and Lamp Life Multpliers for Dimmers
% of Full Light (as perceived by the eye) 100 90 75 50
% of Full Light (as measured) 100 80 56 25
% of Time on Dimmer * 0 100 50 100 50 100 50
Incandescent Lamps Power Reduction Factor 1 0.9 .95 0.8 0.9 0.5 .75
  Lamp Life Multiplier 1 2 1.3 8 1.8 20 1.9
Fluorescent Lamps** Power Reduction Factor 1 0.8 0.9 0.5 .75 0.3 .65
*If dimmers are used only for occasional reduction in illuminance, enter 1.0.
** Fluorescent lamp life is not significantly affected by dimming, so use the value determined by instruction H.


Close Window




Rensselaer Polytechnic Institute
LRC Intranet Web mail Lighting Research Center