The simplest form of linear heat detection, the Kidde Commercial AlarmLine II digital detector, is a non-resettable line type heat detector. AlarmLine II digital detector consists of a range of twin conductor cables with each cable providing a different alarm temperature rating to meet the requirements of a wide range of applications. The sensor cable is constructed of two cores, each insulated with a special polymer which is designed to break down at a specific temperature. The two cores are twisted together creating tension. As the temperature around the cable increases the insulation breaks down and the tension created by the twists forces the two cores to make contact. The contact between the two cores is detected by the monitoring equipment which then triggers an alarm condition.

The AlarmLine II digital detector is available in two different ranges: AlarmLine II Digital detector with international approvals, and AlarmLine II Digital detector EN with EN54-28(2016) approval.