Rancho Cucamonga, CA Noise from Specific Sources: Generator Noise (2026)

Generator noise regulation in unincorporated San Bernardino County applies in layers. Under Title 8 Division 3, a residential standby generator (whole-house natural gas units like Generac or Kohler) must keep sound at or below 55 dBA during day hours and 45 dBA at night at the nearest residential property line. Modern 20-22 kW home standby units rated around 65 dB at 23 feet typically comply when set back 10-20 feet from the lot line with a baffle or sound-deadening enclosure. Portable gas and diesel generators used for RV camping, desert events, and temporary power are louder (70-85 dB at 7 feet) and frequently violate at the property line. During Public Safety Power Shutoffs (PSPS) declared by Southern California Edison and in emergency-declared outages (common in the mountain and desert fire zones), reasonable generator use is effectively tolerated. Stationary generators over 50 horsepower require South Coast Air Quality Management District (SCAQMD) Rule 1470 permits limiting operating hours, typically 50 hours per year for non-emergency use, plus particulate and NOx controls. Data center, warehouse, and cell-tower backup generators are a growing complaint source in the Inland Empire.