New Castle County, DE Outdoor Lighting: Light Trespass & Shielding (2026)

Under UDC Section 40.22.720, non-cutoff luminaires are prohibited countywide in the unincorporated areas the code governs; fixtures must be full-cutoff or semi-cutoff, aimed downward with no direct uplight. Where a non-residential use sits next to a residential district, illumination at the residential property line cannot exceed 0.1 footcandle. Section 40.22.750 requires all exterior lights to be shielded or directed so glare doesn't disturb neighbors or passing motorists, and lighting plans submitted after January 1, 2022 must use LED (or equally efficient) fixtures with warm-white color temperature of 3000K or less. An exterior lighting plan must be filed with the Department of Land Use whenever lighting is installed, substantially modified, or a zoning permit is sought. This is the county's Unified Development Code, which by its own terms (Sec. 40.01.010) governs only the unincorporated areas of New Castle County -- the cities of Wilmington and Newark maintain their own separate zoning and lighting codes not covered here.