Southborough, MA Outdoor Lighting: Light Trespass & Shielding (2026)

Subsection (R) is the operative rule, and the definition in subsection (D) gives it reach: LIGHT TRESPASS is the shining of direct or indirect light produced by a luminaire beyond the boundaries of the lot on which it is located. The bylaw prints no footcandle tolerance at the property line for a lot's own lighting; the standard is no trespass, with the street right-of-way carved out.

Subsection (Q) adds a rule for smaller lights. A spot or flood luminaire rated 900 lumens or less that is directed or focused so as to cast direct light toward residential buildings on adjacent or nearby land, or to create glare perceptible to persons operating motor vehicles on public ways, must be redirected or its light output controlled as necessary to eliminate those conditions. A flood or spot light under the 900-lumen threshold is therefore still reached when it is aimed at neighboring houses. The same subsection reserves to the Planning Board the right to limit and regulate illumination on a project site between 10:00 p.m. and 6:00 a.m.

Coverage and exceptions follow § 174-12.1(B). Flood or spot luminaires rated at 900 lumens or more and other luminaires rated at 1,800 lumens or more are covered, including on single- and two-family residential lots, with exceptions for emergency lighting, hazard warning and temporary decorative or holiday lighting. Applicants in site plan review under § 174-10 must submit a lighting plan with a photometric plan showing illumination in footcandles at the property boundaries, along with evidence that the plan complies with the light trespass restrictions. Sign lighting has its own language in § 174-11(C)(3): light must not be placed, directed or arranged to throw a beam of light, glare or reflection on any street, walk or nearby property of others in a way that creates a traffic hazard or nuisance.