CLD Outdoor Lighting 2 — Questions and Answers
Question 1: Which IES light trespass standard defines the maximum allowable vertical illuminance at a neighboring property line?
- IES TM-15
- IES RP-33
- ANSI/IES TM-21
- IES G-1-03 (Correct answer)
Correct answer: IES G-1-03
IES G-1-03 (Guideline for Security Lighting) and its successor documents specify maximum vertical illuminance limits at property lines to control light trespass.
Question 2: A coastal boardwalk project must protect sea turtle nesting habitat. Which lamp color is most appropriate for fixtures near the beach?
- Cool white (5000K)
- Amber (590nm peak) (Correct answer)
- Blue-white (6500K)
- Neutral white (4000K)
Correct answer: Amber (590nm peak)
Amber light peaking around 590nm has minimal impact on sea turtle navigation instincts, which are most disrupted by short-wavelength (blue/white) light.
Question 3: What is the primary purpose of a photometric cutoff classification (Full Cutoff, Cutoff, Semi-Cutoff) in outdoor luminaires?
- To describe the luminaire's IP rating
- To quantify lumens per watt efficiency
- To control the distribution of light above the horizontal plane (Correct answer)
- To define correlated color temperature ranges
Correct answer: To control the distribution of light above the horizontal plane
Cutoff classifications describe how much light a luminaire emits above the horizontal (90°), directly controlling sky glow and glare contributions.
Question 4: In outdoor sports lighting design, the term 'uniformity ratio' most commonly refers to which measurement?
- Maximum to minimum illuminance (Emax/Emin)
- Average to minimum illuminance (Eavg/Emin) (Correct answer)
- Horizontal to vertical illuminance ratio
- Color rendering index uniformity across the field
Correct answer: Average to minimum illuminance (Eavg/Emin)
Sports lighting uniformity is expressed as average-to-minimum (Eavg/Emin), with IES RP-6 specifying maximum allowable ratios for various sports and competition levels.
Question 5: A pedestrian pathway luminaire is specified at 4m mounting height. Light levels comply but glare complaints arise. Which modification best addresses glare without replacing fixtures?
- Increase lamp wattage
- Add an internal refractor to redirect light downward
- Install a house-side shield to block light toward pedestrians (Correct answer)
- Switch to a higher color temperature source
Correct answer: Install a house-side shield to block light toward pedestrians
House-side shields block direct view of the lamp source from pedestrians' line of sight, reducing disability glare without altering the overall photometric distribution significantly.
Question 6: Which photometric test method is used to characterize near-field data required for accurate roadway lighting simulations?
- Goniophotometry (far-field IES file) (Correct answer)
- Imaging luminance measurement (near-field luminous intensity)
- Integrating sphere measurement
- Spectroradiometric measurement
Correct answer: Goniophotometry (far-field IES file)
Standard goniophotometry produces far-field IES photometric files used in roadway and area lighting simulations; near-field data is a specialized format required only for complex optical modeling.
Question 7: An outdoor plaza uses 3000K LED downlights recessed into a canopy. What CCT would best complement these for accent uplighting on adjacent trees?
- 6500K to maximize brightness contrast
- 2200K for dramatic warmth
- 3000K–3500K to maintain visual coherence (Correct answer)
- 5000K for daylight balance
Correct answer: 3000K–3500K to maintain visual coherence
Matching or closely harmonizing CCT across a scene maintains visual coherence; a 3000K–3500K uplight complements the 3000K downlights without jarring color contrast.
CLD Outdoor Lighting 2
Which IES light trespass standard defines the maximum allowable vertical illuminance at a neighboring property line?