CLD Outdoor Lighting 5

Question 1

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?

Accepted Answer

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

Answer

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.

Question 2

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

Accepted Answer

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

Answer

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.

Question 3

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)?

Accepted Answer

LLD × LDD × voltage variation × thermal factor

Answer

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

Question 4

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

Accepted Answer

'Wet location' use

Answer

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.

Question 5

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:

Accepted Answer

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

Answer

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.

(CLD) Certified Lighting Designer Practice Test

(CLD) Certified Lighting Designer Practice Test

CLD Outdoor Lighting 5