Before answering this question, it will be helpful to define lock "states":
- FAIL SECURE electromechanical locksets that are locked when power is applied remain locked when power is removed. To unlock, power must first be applied.
- FAIL SAFE electromechanical locksets that are locked when power is applied automatically unlock when power is removed.
When a battery in a T2, T3 or Networx stand-alone unit drops below its working voltage, the unit will remain in its last active state:
- A unit unlocked when power is lost will stay unlocked
- A unit locked when power is lost will stay locked
For example, if a unit is locked and an overnight power failure occurs, the premises will not be unsecured. Some units have options that control the lock state under user-defined options. The operation of these units must be determined on an individual basis by means of the lock model.
Note: Many locks use external power to keep the lock operational only when AC power is available; the batteries then become a "backup" to the system.
Andy Phelps, CRL
Alarm Lock National Training Manager