News

The Core Difference: What Happens When Power Is Cut?

Every electrified door lock — electric strikes, magnetic locks, electrified mortise locks, and electric latch retraction devices — must be defined by what it does when electrical power is lost. There are exactly two options:

• Fail Safe (Fail Open): The lock releases and the door can be opened freely when power is lost.
• Fail Secure (Fail Locked): The lock remains locked when power is lost. Mechanical key override is required to open the door.

This single characteristic determines which life safety codes apply, which doors a device can be installed on, and how your access control system must be designed. Specifying the wrong mode can result in a failed inspection, a code violation, or — most seriously — a life safety hazard during an emergency.

How Fail Safe Locks Work

Fail safe locks require continuous electrical power to remain locked. The locking mechanism is held in the locked state by an electromagnet or solenoid that is energized during normal operation. When power is cut — whether by a fire alarm relay, a power outage, or a manual door release button — the electromagnetic force disappears and the door unlocks.

Common Fail Safe Devices

• Magnetic locks (maglocks): By definition always fail safe — power holds the magnet; no power, no magnetism, door opens.
• Fail safe electric strikes: The keeper retracts or releases when de-energized.
• Fail safe electrified mortise or cylindrical locks: The latch or bolt releases on power loss.

When to Specify Fail Safe

Fail safe is required by code on any door that serves as a means of egress in a building governed by NFPA 101 (Life Safety Code) or the International Building Code (IBC). The rationale is straightforward: in a fire or emergency that causes a power failure, occupants must be able to exit without a key or credential. Locking them in would be a life safety violation.

Fail safe is also required when:

• The door is in a fire-rated corridor or stairwell serving as an egress path
• The building uses a fire alarm interface that must release all secured doors on activation
• The Authority Having Jurisdiction (AHJ) or local fire marshal has mandated free egress
• The door leads to an area of refuge or accessible means of egress per IBC Section 1009

How Fail Secure Locks Work

Fail secure locks require power to unlock. The locking mechanism is held in the locked state mechanically (by a spring-loaded bolt or latch), and power is applied to retract it and allow entry. When power is lost, the mechanical lock engages and the door cannot be opened without a physical key.

Common Fail Secure Devices

• Fail secure electric strikes: The keeper remains locked; power is required to release it for entry.
• Fail secure electrified mortise locks: The electric latch retraction or electric trim function requires power to operate.
• Electromagnetic deadbolts: Some configurations use energize-to-retract deadbolt designs.

When to Specify Fail Secure

Fail secure is appropriate for doors where security must be maintained even during a power failure, and where the door is not a required means of egress (or where the egress path provides other compliant exit routes). Common applications include:

• Server rooms and IT infrastructure areas
• Pharmacy and narcotics storage (DEA regulations often mandate maintained security)
• Secure document storage and records rooms
• Cash handling rooms in retail and banking
• Data centers and high-security offices
• Doors that are access-controlled for entry only, with free mechanical egress always available on the inside (push bar, lever with no power requirement)

NFPA 101 and IBC Requirements

The two primary model codes governing electrified door hardware in commercial buildings are NFPA 101: Life Safety Code and the International Building Code (IBC). Both codes have been adopted — in original or amended form — by most US jurisdictions.

NFPA 101 Key Provisions

• Section 7.2.1.5.5 (Electrically Controlled Egress Door Assemblies): Egress doors with access-controlled hardware must unlock upon fire alarm activation, loss of power, or manual release at a location approved by the AHJ. This effectively mandates fail safe behavior on egress paths.
• Section 7.2.1.6 (Special Locking Arrangements): Permits delayed-egress locks and access-controlled locks under specific conditions, but requires power-failure release (fail safe) in all cases.

IBC Key Provisions

• Section 1010.1.9.8 (Access-Controlled Egress Doors): Allows electric strikes and other access control devices on egress doors if the system is equipped to release on: (1) fire alarm activation, (2) loss of power, and (3) a manual release device at the door. All three conditions point to fail safe.
• Section 1010.1.9.9 (Electromagnetically Locked Egress Doors): Magnetic locks on egress doors must release on fire alarm, loss of power, and activation of a readily accessible release device (e.g., a push-button or motion sensor on the egress side).

The Egress Side Rule

A critical concept: the fail safe / fail secure designation applies to the side of the door that matters for life safety — the egress side. A fail secure electric strike on an entry door is code-compliant as long as the egress side has free mechanical release (a lever, push bar, or touch bar that operates without power or credentials). This configuration — fail secure for entry, free egress — is the most common setup for access-controlled interior doors in commercial buildings.

Fire Alarm Interface: A Non-Negotiable Requirement

Any electrified locking device on a door in the means of egress must be interfaced with the building fire alarm system. On alarm activation, the fire alarm control panel (FACP) sends a signal that cuts power to fail safe locks (releasing them) or activates a shunt circuit. This interface is typically accomplished through:

• A relay module connected to the FACP NAC (Notification Appliance Circuit)
• A dedicated door release output from the FACP
• A UL 294-listed access control system with fire alarm integration

Failure to integrate the fire alarm is a code violation and will be flagged during fire inspection.

Power Supply Considerations

The power supply requirements differ significantly between the two modes:

Fail safe locks — especially magnetic locks — require a UPS (uninterruptible power supply) if you want them to remain locked during a power outage. Without a UPS, any power interruption will release the door. This is by design for life safety, but may be operationally undesirable in non-emergency situations (e.g., a brief power flicker unlocking a perimeter door).

Quick Decision Guide

Dual-Mode and Field-Selectable Locks

Some electric strikes and electrified locksets are available in field-selectable fail safe / fail secure versions, where the installer can configure the mode during installation using a switch or jumper inside the device. This simplifies stocking for distributors and contractors but requires careful configuration and documentation. Always confirm the as-installed mode matches the specification and AHJ approval before commissioning.

Browse our full lineup of fail safe and fail secure electric strikes at Park Avenue Locks — with expert support to help you spec the right mode for every opening.