Describes requirements for construction, installation and operation of intruder alarm systems installed in buildings, where main interconnections are by physical conductors. Such systems have one or more detectors, one or more control equipments, one or more warning devices and/or signalling equipments and power supply equipment. Excludes systems in which detectors are deliberately-operated devices (e.g., 'bandit alarm' systems) or systems which use mains wire or wire-free connections within a premises other than for portable deliberately-operated devices within a system.