Concord, CA Outdoor Lighting: Light Trespass (2026)

Light spillover - also called light trespass - occurs when artificial light crosses a property line and disturbs a neighbor. CMC Title 18 Development Code establishes a performance standard of zero foot-candles measured at any residential property line for commercial and multifamily projects. Residential-to-residential light spillover is addressed through CMC nuisance provisions (Title 8) and Civil Code 3479, which define unreasonable lighting that substantially interferes with the enjoyment of neighboring property as a private nuisance. Common violations include: security floodlights aimed horizontally at the fence line, unshielded ground-mounted landscape uplights that shine into second-story bedrooms, dusk-to-dawn wall packs with no shielding, holiday string lighting left up year-round, and bright LED signage facing residences. Remedies begin with neighbor communication, then Code Enforcement complaints (which focus on shielding and aim adjustments), and ultimately civil suits for private nuisance. Sign illumination is separately regulated under the sign chapter of Title 18 - internally illuminated signs must dim or turn off per zoning district curfew (typically 11 PM in commercial-adjacent-residential). Automobile dealership and parking-lot lighting, a common regional source of glare, must comply with full-cutoff requirements and extinguish non-security fixtures after business hours.