ABSTRACT
The first line of defence against intrusion includes physical measures that resist unwanted entry to the grounds and structure of a building. The second line of defence is an alarm system. Alarm installations hard wired systems to British Standards EN 50131 are the most reliable and conform to the association of chief police officers alarm policy. Police response to alarm activations depends on the type of alarm system installed. Intruder alarms have developed from a very limited specialist element of electrical installation work in high security buildings to the much wider market of schools, shops, offices, housing, etc. Extended links can and also the be established with the local police, a security company facility manager's central control by telecommunication connection. Selection of switches to effect the alarm will depend on the building purpose, the extent of security specified, the building location and the construction features.
