Is it correct that car and burglar alarms are supposed to switch themselves off after 20 minutes – or is that just a myth?
There’s a code of practice requiring installers and manufacturers to include such a cut-out device on burglar alarms. As far as vehicles are concerned, the Road Vehicle (Construction and Use) Regulations 1986 require a five-minute cut-out device on alarms. An EC Directive limits this to 30 seconds, unless the alarm detects continued interference, in which case the alarm can repeat for up to five minutes. New vehicle types were required to have these alarms from 1st January 1997, and existing vehicle types (current models) were required to have them included from 1st October 1998.