Greenwich, CT Noise from Specific Sources: Generator Noise (2026)

Section 6B-6(d) of the Code of Ordinances bars discharging into the ambient air "the blow-down of any steam vent of the exhaust of any stationary internal combustion engine or air-compressor equipment" unless the discharge passes through a muffler, as defined in § 6B-2(n), or an apparatus providing equal noise reduction. A generator that runs on a gasoline, diesel or similar internal combustion engine and sits fixed on a property, rather than moving under its own power, falls within "stationary internal combustion engine," so the exhaust-muffler rule applies to backup and portable standby generators used outdoors.

Section 6B-2(n) defines "muffler" simply as a device for abating sounds such as escaping gasses, leaving compliance to whether the device actually cuts the noise, not to a brand or model list. Beyond the muffler mandate, generator noise is also capped by the general property-line decibel table in § 6B-5(c): up to 55 dBA into a residential receptor by day and 45 dBA at night from a residential-zone source, or 62 dBA between business properties. Running an unmuffled generator overnight can also trip the domestic power-tool curfew in § 6B-6(e)(1) if it is the kind of tool or equipment that section covers, and the emergency-equipment maintenance rule in § 6B-6(f) separately bars testing necessary emergency equipment for non-emergency purposes between 5:00 p.m. and 9:00 a.m. on weekdays and at any time on weekends.