Janesville, WI Outdoor Lighting: Light Trespass & Shielding (2026)

Section 42-389, within Article XI's physical-development standards for O1-O3, B1-B6 and BT zoned development under Section 42-386(a), directly targets light spilling onto neighboring land. Subsection (5)f sets the numeric limit: the illumination level at any property line cannot exceed 0.5 footcandle above the ambient lighting conditions measured on a cloudless night, a specific ceiling on how much extra light a development may throw across its boundary. Subsection (5)g backs that with a fixture-orientation rule, providing that in no instance may an outdoor lighting fixture be mounted or oriented so that the lighting element itself is visible from any residence located in a residential zone district, meaning glare shielding is required even where the 0.5 footcandle threshold is met.

Subsection (5)e adds a uniformity check, capping the ratio of average to minimum illumination on the lit surface at 4:1 so light is not concentrated in ways that increase spillover. Subsection (5)b requires that illumination of a site avoid competing with lighting on adjoining or neighboring properties, reinforcing the trespass limit as a design principle rather than just a numeric ceiling. Compliance is verified through the lighting and photometric plan the Site Plan Review Coordinator requires under Subsection (5)l before development proceeds.