Fail-Safe and Fail-Secure Access-Control Locks
Compare loss-of-power lock behavior, distinguish secure-side access from egress and door position, and record the exact lock, strike and system documentation.
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Distinguish the observed states
Fail-safe and fail-secure describe the electrified locking function when its power is removed. They do not, by themselves, describe door position, permitted egress, backup supply behavior or fire-alarm release. Always identify which side and which hardware function are being discussed.
| Term / condition | Meaning | Separate question |
|---|---|---|
| Fail-safe function | Electrified locking function unlocks when power is removed. | Does the door remain physically closed, and how does the full opening operate? |
| Fail-secure function | Electrified locking function remains locked when power is removed. | Is mechanical egress independently available through the specified hardware? |
| Door position | Open/closed state reported by a door-position switch. | A closed door signal does not prove the latch or lock is secure. |
| Lock monitoring | A product-specific indication of latch, bond or other condition. | Which physical condition is actually monitored? |
| Battery backup | Power may continue after loss of normal AC input. | When does the locking device actually lose its supply? |
Read the complete opening hardware set
Allegion distinguishes secure-side access behavior from free egress on many electromechanical products. Do not generalize that relationship to every lock, strike, electromagnetic lock or controlled-egress arrangement. Field-selectable modes and product variants require the exact instructions.
- Identify the lock/strike model and configured power-loss mode.
- Record supply, controller outputs and backup-power arrangement.
- Read the hardware set for inside operation and mechanical release.
- Record the project-approved fire-alarm and emergency-release documentation.
Keep a functional record
Use separate columns for normal power, backup power, lock command, monitored lock state and door position. Record an observed test against the documented sequence rather than labeling the opening compliant based on “fail-safe.”
The choice of hardware and release sequence depends on the opening and applicable requirements. This page gives no egress compliance determination. Link the cable endpoints and functional test record; current demand and battery sizing remain separate calculations.
For the separate numerical task, use access-control power supply. Use the equipment data identified above as inputs within each tool’s stated scope.