New Castle County, DE Outdoor Lighting: Dark Sky Rules (2026)
Key Facts
- Non-cutoff fixtures
- Prohibited outright
- Required standard
- Full-cutoff, fully shielded, no uplight
- Residential property line cap
- 0.1 footcandle
- Exempt below
- 500 lumens (e.g., 40W incandescent)
- Applies to
- Unincorporated County only
Summary
New Castle County bans non-cutoff light fixtures and requires full-cutoff, downward-shielded luminaires on new or modified exterior lighting in unincorporated areas, capping illumination near homes at 0.1 footcandle.
A.Light fixtures, or luminaires, are available in different types including...:1.Non-cutoff fixtures, which are prohibited;2.Semi-cutoff fixtures, which direct the light to partially limit view of the light source; and3.Full cutoff fixtures which shield the light source from view and prevent upward light... B.All luminaire output is to be aimed downward and shall meet Illuminating Engineering Society ("IES") full-cutoff/fully shielded criteria where possible, and have no direct uplight.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 5).
Full Breakdown
Under UDC Section 40.22.720, New Castle County prohibits non-cutoff outdoor light fixtures outright and requires new or substantially modified exterior lighting to use full-cutoff, fully shielded luminaires aimed downward with no direct uplight, meeting Illuminating Engineering Society full-cutoff criteria. Fixtures rated at 500 lumens or less, such as a standard 40-watt incandescent bulb, are exempt. Where a non-residential use sits next to a residential district, illumination measured at the residential property line cannot exceed 0.1 footcandle. The Unified Development Code applies only to unincorporated New Castle County; Wilmington and Newark enforce their own separate zoning and lighting codes.
Violations & Fines
Installing non-cutoff, unshielded fixtures on a project subject to zoning review can hold up permit approval; the Department of Land Use enforces compliance through the site/lighting plan review process.
Frequently Asked Questions
Does this rule apply inside Wilmington or Newark?
Are small residential fixtures like porch lights covered?
What is the maximum brightness allowed near a home?
Sources & Official References
Other rules in New Castle County
Compare New Castle County to another location·View the Delaware outdoor lighting overview
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