Lighting Standards, Codes, and Design Criteria
Domain 2 - Lighting Standards, Codes, and Design Criteria
This domain tests whether you can select the right design method and apply the governing documents: IES RP-8 for roadway and parking-facility lighting, NEC Articles 225, 250, 300, and 410 for electrical installation, AASHTO LTS for supports, and MUTCD Part 6 for temporary traffic control. The exam emphasizes criteria selection, not memorizing every table.
Design method and criteria
- Roadways are commonly designed by luminance (average maintained cd/m² and uniformity), while sidewalks, crossings, and conflict areas often use illuminance (lux or fc).
- Design inputs include road functional class, pedestrian conflict level, pavement reflectance (R-table), speed, and intersection or conflict density.
- Criteria typically include average maintained luminance or illuminance, max/min uniformity, average/min uniformity, and veiling luminance ratio.
- Maintenance factor combines lamp lumen depreciation, luminaire dirt depreciation, and equipment factor. Design values are maintained, not initial.
- Adaptive lighting may reduce levels during low-traffic hours, but transitions and minimum levels must be justified.
Worked example
Four luminance readings on a lane are 1.2, 1.0, 0.8, and 0.6 cd/m². Average = 0.9; max/min = 2.0; average/min = 1.5. If the specified criteria are average ≥0.8 cd/m², max/min ≤3.0, and average/min ≤6.0, the layout passes on these sample points. If the 0.6 reading fell to 0.3, average would be 0.825, max/min 4.0, and average/min about 2.75 - max/min would fail.
Traps that cost marks
Applying roadway criteria to a parking lot, using initial lumens in a maintained calculation, checking uniformity on too few points, ignoring veiling luminance at intersections, and citing a code article for a design criterion that actually comes from RP-8.