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Residential Lighting and 2008 Title 24 Part 2 - High Efficacy Lighting

What exactly does the code mean when it says "high efficacy or low efficacy fixture"?

First a couple definitions: The code doesn't use the term fixture. They use the lighting industry term "luminaire". This is the housing, lamp holder and ballast if present. Neither does it use the term bulb. It is referred to as a "lamp".

Efficacy is similiar to miles per gallon in your car. In this case it is a measure of lumens per watt. Lumens are a measure of visible light. Typically fluorescent, some LED lighting, metal halide or high pressure sodium for exteriors are considered high efficacy. Incandescent and halogen would be considered low efficacy.

So how many lumens per watt are required? Table 150-C of the code lists the following:

Table 6-1 - High Efficacy Lamps - Other Than LED Lighting

Lamp Power
Minimum Lamp Efficacy
5 W or less
30 lm/W
over 5 W to 15 W
40 lm/W
over 15 W to 40 W
50 lm/W
over 40 W
60 lm/W

A standard incandescent lamp is around 12 lumens/watt. A typical CFL lamp would be in the 40-50 lumen/watt range. Some of the newer LEDs are reported to reach 90 lumens/watt.

Where do we find the lumens for a particular luminaire? Typically on the lamp specified for the luminaire or in the manufacturer's documentation or catalog.

Some other features the code lists to differentiate low efficacy luminaires:

  • A luminaire that has any type of line voltage socket or lamp holder that accepts any kind of incandescent lamp.
  • Low voltage incandescent lighting
  • Track lighting
  • LED lighting that has not been certified by the CEC. We'll talk about this more in a later post, but it is definitely something for builders, architects and anyone specifying light fixtures to keep in mind.
  • Electrical boxes that have a blank cover or where no luminaire is installed. Another one especially for builders. I can't count the number of times building custom homes, where at final inspection a decorative fixture was on back order and we put a blank cover over the box, or where we were going to install a chandelier over a jetted tub after inspection.

For more information here is the link to the 2008 T24 Residential Compliance Manual:

Next post in this series we'll talk about requirements for other rooms in the home.


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