Placentia, CA Noise from Specific Sources: Car Alarm Limits (2026)

Chapter 10.38, the Placentia Alarm System Ordinance, regulates burglary, robbery, fire and medical assistance alarm systems in buildings, structures and facilities. It requires an alarm system permit before installation or operation, with the permit valid for 24 months, and requires the subscriber to name at least three contacts. It requires subscribers to reimburse the city for police or fire responses to false alarms, in an amount set by city council resolution. Section 10.38.050 requires a subscriber to silence an alarm within 30 minutes of notification for a residential structure or 45 minutes for a commercial or industrial structure, and § 10.38.110 treats a system that generates more than three false alarms in a 90 day period, four in 180 days, or five or more in 12 months as a public nuisance that can be placed on nonresponse status.

None of that applies to a car. Section 10.38.120(a) provides that the chapter does not apply to audible alarms affixed to automobiles. The permit, the false-alarm reimbursement and nonresponse status therefore stay with building alarms. The siren-sound ban in § 10.38.140(a) is likewise written for an alarm system or device installed or maintained on the exterior or interior of any building.

The noise chapter is a separate matter. Section 23.76.020 defines a mobile noise source as any noise source other than a fixed noise source, and § 23.76.050(b) makes it unlawful to create any noise, or allow its creation on property one controls, that exceeds the zone standards on another property: for residential property, 55 dB(A) from 7:00 a.m. to 10:00 p.m. and 50 dB(A) from 10:00 p.m. to 7:00 a.m., and for any other zone as the table prints. The list of exempt activities in § 23.76.070 does not name vehicle alarms. The code prints no dedicated car alarm duration limit.