Fail-Safe vs. Fail-Secure Locks: What’s the Difference?

Overview: Fail-Safe vs. Fail-Secure Locks

When specifying or installing electrified locks, strikes, or other access control devices, one of the most important considerations is what happens if the power goes out or the system fails. This is where the concepts of fail-safe and fail-secure come into play. Here’s a quick breakdown of the two:

1. What Is a Fail-Safe Lock?

• Definition: A fail-safe lock is designed to unlock when it loses power.
• Behavior on Power Loss: Upon power failure, the door becomes unlocked.
• Ideal Use Cases:
  • Areas where safe exit during an emergency is a priority (e.g., stairwell doors, building exits).
  • Situations where rapid egress is mandatory if the system fails or the building loses power.
• Example: Most electromagnetic (mag) locks are fail-safe by nature. When power is cut, the electromagnet de-energizes and the door becomes free to open.

2. What Is a Fail-Secure Lock?

• Definition: A fail-secure lock is designed to remain locked (secure) when it loses power.
• Behavior on Power Loss: Upon power failure, the door stays locked on the outside but typically allows free egress from the inside (to ensure occupant safety).
• Ideal Use Cases:
  • High-security areas where preventing unauthorized entry is paramount (e.g., server rooms, sensitive data centers).
  • Places requiring continued security even if the building’s power is disrupted.
• Example: Many electric strikes can be configured to be fail-secure. If the power goes out, they keep the door latch engaged, preventing entry from outside.

3. Key Differences at a Glance

CharacteristicFail-SafeFail-SecureState if Power FailsUnlocks (safe for exit)Remains locked (secure from outside)Primary ConcernLife safety and quick egressSecurity against unauthorized entryTypical ApplicationsEmergency exits, stairwell doorsServer rooms, security doorsCommon TechnologyElectromagnetic locks (maglocks)Electric strikes

4. Choosing the Right Option

• Life Safety Regulations: Building codes often require certain doors to be fail-safe (especially on egress routes) so occupants can evacuate quickly in emergencies.
• Security Requirements: For high-security zones, fail-secure locks ensure protection against unauthorized access even when power is lost.

In many buildings, you might see a mix of both. Perimeter doors or server rooms might need fail-secure locks, while main exits and emergency paths employ fail-safe locks to comply with life-safety requirements.

Summary

• Fail-Safe locks ensure unrestricted exit upon power loss (prioritizing life safety).
• Fail-Secure locks maintain security upon power loss (prioritizing asset protection).

Understanding these two modes helps in selecting the right hardware for each opening—balancing safety codes, security needs, and overall building operation.