Inside The Details: California’s Title 24, Part 2

By Stephen Carr | Aug 15, 2016




Last month, I went over a brief history of California’s Title 24, Part 6, the current rules and what’s coming up. This month, let’s get more detailed about some of the current rules. In a nutshell, the rules are designed to reduce energy use in unoccupied areas, including offices, corridors, stairwells, library stacks, parking garages and other intermittently occupied areas. Lighting fixtures have been the focus of this effort from Title 24’s earliest versions. 

What’s ‘efficacy’?

At first, one of the requirements I didn’t understand regarded high-efficacy luminaires, because I didn’t know what high efficacy was. I didn’t even know what “efficacy” meant, so let’s start there.

Efficacy is a synonym for effectiveness and is defined as “capacity for producing a desired result.” In the context of energy savings, it defines how efficient a lamp is at producing light from energy. The International Code Council (ICC) defines high efficacy as 60 lumens per watt (LPW) for lamps over 40 watts (W), 50 LPW for lamps between 15 and 40W, and 40 LPW for lamps 15W or less. As a result, our old friend, the incandescent lamp, has been relegated to the low-efficacy category, because it only creates 20 LPW. Most fluorescent, high-intensity discharge (HID) and light-emitting diode (LED) lamps are high efficacy.

Now, let’s define a high-efficacy luminaire. Simply put, it must not contain a socket that allows a low-efficacy lamp to be installed. For example, a standard table lamp with a medium-base screw socket is a low-efficacy luminaire, even if you install an LED lamp, because you have the option to install a low-efficacy incandescent lamp.

Typically, high-efficacy luminaires contain pin-based sockets or screw sockets specifically rated only for HID lamps, such as high-pressure sodium. In addition, for new residential projects, Title 24 requires LED luminaires to have a color rendering index (CRI) of 90 and a correlated color temperature (CCT) between 2,700K and 4,000K to qualify as high-efficacy. 

Some like it hot

I know. It’s time for more definitions. The CCT defines the shade of white light a lamp emits. The exact color is measured in degrees on the Kelvin scale. For example, 2,700K is considered warm, with more yellow in it, 4,000K is considered to be a natural white, and 4,800K is direct sunlight. A cool white lamp starts adding some blue and has a range of 7,000K to 7,500K. 

CRI is a scale from 0–100 percent, indicating how accurate a given light source is at rendering color when compared to a reference light source. The higher the CRI, the better the color rendering ability. Unfortunately, these ratings have been the victim of inaccurate testing and marketing deception. 

It is up to you to understand what you are getting when purchasing lamps and luminaires. It would not be good if your customers’ faces appeared to be a sickly yellow or a ghostly blue under the lighting system you installed.

Receptacle business

The 2013 version of Title 24 added receptacles to the list of things that must be turned off when an area is not occupied. Specifically, there must be a controlled receptacle within 6 feet of every uncontrolled receptacle. 

I have seen this accomplished two different ways. The first interprets the rule literally by placing a controlled receptacle near every uncontrolled receptacle. The second method makes every receptacle half-switched, with one half always on and the other half controlled.

It is important to note here that the National Electrical Code requires all receptacles switched from a remote location to be permanently labeled “controlled.” This can be accomplished by attaching permanent labels or by installing factory-inscribed receptacles. Inscribed receptacles are available with only one or both outlets labeled, as needed to work with both the whole or half-switched schemes. They are also available in standard and decorator versions. Be careful when selecting an inscribed receptacle, because the pricing runs from just a few dollars to more than $20. 

Meeting demand

The demand-shed reduction rule has also changed. It requires the lighting load for an entire building to be reduced in response to a signal. The signal can come from several sources, such as a local utility. The 2008 Title 24 required this function for retail buildings with sales floor areas greater than 50,000 square feet. The new version calls for all nonresidential buildings greater than 10,000 square feet to be able to respond to a signal cutting lighting power at least 15 percent below maximum.

Wherever you bid, you need to understand the energy codes that are in effect in your jurisdiction. Leaving out half of a lighting control system or forgetting to label your receptacles is not the way to earn your annual bonus.

About The Author

CARR has been in the electrical construction business since 1971. He started Carr Consulting Services—which provides electrical estimating and educational services—in 1994. Contact him at 805.523.1575 or [email protected], and read his blog at





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