What are Lumens (watts) ?

Lumens/Watts
A ratio expressing the luminous efficacy of a light source. Typical lamp efficacies:

  • Thomas Edison's first lamp - 1.4 lpW
  • Incandescent lamps - 10-40
  • Halogen incandescent lamps - 20-45
  • Fluorescent lamps - 35-105
  • Mercury lamps - 50-60
  • Metal halide lamps - 60-120
  • High-pressure sodium lamps - 60-140

Note: The values above for discharge lamps do not include the effect of the ballasts, which must be used with those lamps. Taking ballast losses into account reduces "system" or lamp-ballast efficacies typically by 10-20% depending upon the type of ballast used.


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