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"The information on this website is meant to provide a general overview of the tax provisions for the interim rules of lighting systems listed in the Energy Policy Act of 2005. In all cases the services of a professional tax accountant should be retained to determine the specific tax treatment appropriate for your company. Requirements for lighting levels and controls, in accordance with EPAct 2005, must also be satisfied for eligibility. Rexel will not, in any way, accept any liability for decisions made based on the contents of this preliminary explanation."

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Scotopic/Photopic (S/P) Ratio
This measurement accounts for the fact that of the two light sensors in the retina, rods are more sensitive to blue light (pcotopic vision) and cones to yellow light (photopic vision). The pcotopic/photopic (S/P) ratio is an attempt to capture the relative strengths of these two responses. S/P is calculated as the ration of scotopic lumens to photopic lumens for the light source on an ANSI reference ballast. Cooler sources (higher color temperatures lamps) tend to have higher values of the S/P ratio compared to warm sources.

Shielding
A general term to include all devices used to block, diffuse or redirect light rays, including baffles, louvers, shades, diffusers and lenses.

Shielding Angle
The complementary angle of the cut-off angle of a luminaire.

Slimline Lamp
Fluorescent lamp, which has single pin contacts, that requires no filament heating to ignite.

Specification Series (SP) Colors
Energy-efficient, all-purpose, tri-phosphor fluorescent lamp colors that provide good color rendering. The CRI for SP colors is 70 or above and varies by specific lamp type.

Specification Series Deluxe (SPX) Colors
Energy-efficient, all-purpose, tri-phosphor fluorescent lamp colors that provide better color rendering than Specification Series (SP) colors. The CRI for SPX colors is 80 or above and varies by specific lamp type.

Spectral Power Distribution (SPD)
A graph of the radiant power emitted by a light source as a function of wavelength. SPDs provide a visual profile or "finger print" of the color characteristics of the source throughout the visible part of the spectrum.

Starting Temperature
The minimum ambient temperature at which the lamp will start. Light output may be affected due to lamp characteristics.

System efficacy
Overall efficiency of the lamp/ballast system. System efficacy = total lamp lumens / system wattage.

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