Outdoor Lighting Flashcards

A city specifies a minimum Color Rendering Index (CRI) of 70 for new street lighting. A proposed LED fixture has CRI 72 but a poor R9 value of 10. What concern does this raise?

Answer: Saturated red objects such as brake lights and stop signs may appear washed out or brownish

R9 measures rendering of saturated red; a very low R9 (even with CRI ≥ 70) means red safety-critical elements like brake lights and stop signs appear desaturated, reducing visual safety cues.

What is 'ecological light pollution' and which wavelength range is of greatest concern for insect populations?

Answer: Ultraviolet and short-wavelength blue-green light attracting and disorienting insects

Insects are highly sensitive to UV and short-wavelength blue-green light (300–550nm), which attracts and disorients them around artificial light sources, disrupting feeding, mating, and predator-prey relationships.

A designer is calculating the maintained illuminance for an outdoor walkway after 5 years. Which combination of factors comprises the overall Light Loss Factor (LLF)?

Answer: LLD × LDD × voltage variation × thermal factor

The comprehensive LLF includes all recoverable and non-recoverable factors: lamp lumen depreciation, luminaire dirt depreciation, voltage variation, and temperature effects on output.

Under NFPA 70 (National Electrical Code), outdoor luminaires installed in wet locations must be listed and labeled for:

Answer: 'Wet location' use

NEC Article 410.10(A) requires luminaires exposed to weather or water to be listed specifically for wet locations; 'damp location' listings are insufficient for direct rain or water exposure.

A sports broadcaster requests lighting for a multi-camera HD broadcast at a stadium. The primary additional photometric requirement compared to recreational play illuminance is:

Answer: Increased vertical illuminance levels and uniformity to adequately illuminate players' faces and vertical surfaces for cameras

Broadcast cameras require high vertical illuminance (not just horizontal) on player faces and vertical surfaces, with tight uniformity ratios (Emax/Emin ≤ 2.0) to avoid overexposed and underexposed zones in the frame.

Which material property makes Type 316 stainless steel preferable to Type 304 stainless steel for coastal outdoor luminaire hardware?

Answer: Molybdenum content providing superior resistance to chloride (salt) corrosion

Type 316 stainless steel contains 2–3% molybdenum, which significantly improves resistance to chloride-induced pitting and crevice corrosion common in coastal salt-air environments.

A historic district ordinance restricts luminaire height to 3.5m on a pedestrian street 6m wide. If a designer cannot meet IES RP-8 illuminance recommendations at this height, what is the most appropriate design response?

Answer: Reduce pole spacing and potentially use opposite-side staggered or opposite-side opposing configurations to achieve coverage

Reducing pole spacing and using a staggered or opposing pole layout distributes overlapping light pools more evenly, compensating for the reduced mounting height constraint.