What is the required illumination level on tread runs of stairways within a dwelling unit?

The correct illumination level on tread runs of stairways within a dwelling unit is 1 footcandle. This standard is established to ensure safe navigation of stairways within residential settings. Adequate illumination is critical in preventing accidents such as slips and falls, especially in areas where visibility can be limited.

Stairways are often locations where individuals may be focused on their footing rather than their surroundings. Therefore, having a minimum illumination level of 1 footcandle provides sufficient visibility for users to clearly see each step and any potential obstacles. This requirement balances the need for safety with practical lighting considerations; too much illumination can lead to glare and discomfort, while insufficient lighting increases the risk of accidents.

Higher illumination levels, such as 2 footcandles or more, may be beneficial in certain scenarios but are not required by code for residential stairways. Thus, the established standard of 1 footcandle is deemed sufficient for safety while allowing for more energy-efficient lighting solutions.