To ensure effective visual performance, the task area luminance ratios in Table 12.2 should not be exceeded.
Additional Information: To determine task lighting requirements, it is necessary to consider the levels of lighting that surround a task. Great disparities between task and background lighting can lead to adaptation problems.0700
Table 12.2 Maximum Task Area Luminance Ratios
Areas |
Luminance Ratio |
Task area versus adjacent darker surroundings |
3:1 |
Task area versus adjacent lighter surroundings |
1:3 |
Task area versus more remote darker surfaces |
10:1 |
Task area versus more remote lighter surfaces |
1:10 |
Luminaires versus surfaces adjacent to them |
20:1 |
Anywhere within normal field of view |
40:1 |