The Decision That Happens After the Spec Is Written
This article is for electrical contractors, low-voltage integrators, and facility managers who are past the point of choosing a fail safe electrified mortise lock and are now staring at the wiring diagram wondering what comes next. The lock function on the hardware schedule tells you what the lock does. What it does not tell you is how power delivery, fire alarm interface, and access control sequencing interact once the door is in service. Getting those three things aligned is where openings succeed or quietly fail.
What Fail Safe Actually Means at the Lock Body
A fail safe electrified mortise lock is one that requires continuous power to maintain a locked state. When power is interrupted — whether by a fire alarm release, a panel dropout, or a simple breaker trip — the lock releases and the door becomes freely operable from both sides.
On a single-cylinder, both-levers-locked function (the configuration where neither lever operates without a credential or key), fail safe means that a power loss gives anyone free passage through that opening. That is the intended behavior on most egress-critical doors. It is not the right behavior everywhere, and understanding that distinction drives every wiring and sequencing decision that follows.
The Three Layers Most Specs Do Not Fully Address
Layer 1 — Power Supply Sizing and Voltage Drop
EcoFlex-platform mortise locks in the commercial Grade 1 category typically operate on 12VDC or 24VDC and draw a low continuous current in the solenoid-energized (locked) state. The peak inrush at the moment of switching can be significantly higher — often stated in the 500mA range per device — and a power supply serving multiple locks must be sized for the cumulative inrush, not just the steady-state draw.
Voltage drop over wire runs is the hidden enemy. At longer runs — 150 feet, 200 feet, or more — the gauge required to keep voltage within the manufacturer's tolerance window climbs. Operating outside of the specified voltage range (typically plus or minus 10 percent) can cause the solenoid to chatter, fail to release cleanly, or reduce service life. Specify wire gauge based on your actual run length and load, not just what fits through the conduit conveniently.
- Use 24VDC when wire runs are long — it tolerates voltage drop better than 12VDC at the same gauge.
- Calculate wire gauge from the one-way run length and the expected load current, then confirm against the lock manufacturer's wire gauge chart.
- Never share a power supply circuit with devices that create electrical noise (intercoms, mag-holders on heavy doors) without appropriate filtering or isolation.
Layer 2 — Fire Alarm Interface and Code Requirements
In a fail safe configuration, the lock must release upon fire alarm activation. This is not optional in any occupancy governed by NFPA 101 or the IBC. But the mechanism of that release matters.
The cleanest approach is running power to the lock through a fire alarm control panel (FACP) relay or a listed power supply with fire alarm input. When the FACP signals alarm, the relay opens, power drops, and every fail safe lock on that circuit releases immediately. No software command required, no access control panel in the signal path, no communication delay.
A common field mistake is routing fire alarm release through the access control panel instead of directly through the power supply. If the access control system is slow to respond, network-dependent, or simply offline during the event, the lock may not release on time. Fire life safety systems must be hardwired to interrupt power at the source — do not let software be the last line of defense on an egress door.
- Fire alarm interface should interrupt power to the lock directly — not through an access control command.
- Coordinate with Division 26 (electrical) and Division 28 (electronic safety and security) early; electrified door hardware cannot be specified in isolation.
- Confirm with the authority having jurisdiction (AHJ) whether the occupancy requires panic hardware at the same opening — fail safe mortise locks and panic hardware have different egress rules that must be reconciled at the spec stage.
Layer 3 — Access Control Sequencing When Both Levers Are Locked
A both-levers-locked mortise function is one of the more nuanced configurations in commercial hardware. In the de-energized (fail safe, power-off) state, both levers are free. In the energized (power-on, normal operation) state, both levers are locked and the door requires a credential — card, fob, code, or key cylinder — to operate.
This configuration appears frequently in:
- Healthcare corridors and controlled medication rooms — where staff must credential in and patients should not be able to wander out undetected.
- School administrative wings and secure vestibules — where the inside lever being locked forces occupants to use the access control credential even when exiting.
- Industrial and manufacturing secure zones — where tracking egress is as important as controlling ingress.
- Retail back-of-house and cash handling rooms — where anti-passback or audit trails require credentialed exit.
The sequencing question that catches integrators off guard: what does the access control panel instruct the lock to do during a scheduled unlock period? If the panel sends an unlock command, it de-energizes the lock (fail safe: power off equals unlocked). The levers become free. That is the correct behavior for a scheduled free-egress period — but only if the installer and the facility manager both understand that an unlock command on a fail safe lock cuts power rather than adding it. Confusion here leads to incorrect relay logic, inverted output wiring, and doors that lock when they should open.
The ElectroLynx Question: Pre-Wired Door or Field-Wired?
Getting power from the frame to the lock body on a mortise-prepped hollow metal door requires a power transfer method. Doors manufactured with ElectroLynx connectors built in simplify this considerably — the through-door wiring harness is already in place and the installer connects at the hinge and at the lock. Doors without factory wiring require either a retrofit harness, an electric hinge, or a through-door raceway with field-pulled wire.
Before ordering, confirm:
- Whether the door was manufactured with a built-in wiring harness.
- Whether the door can accept a 5/8-inch chase for a standard connector-terminated cable, or whether a pinned-end cable is needed because of steel stiffeners or glass kits.
- Which hinge position is carrying the power transfer — and whether that hinge is already specified as an electrified hinge or continuous-hinge power transfer device.
Mismatched connector types between the lock and the transfer device are among the most common reasons an electrified opening fails its pre-installation bench test. Verify compatibility before the door goes in the frame.
Monitoring Outputs: The Feature That Gets Overlooked Until Move-In Day
Many commercial-grade electrified mortise locks include monitor switch outputs that report lock status — locked, unlocked, door position — back to the access control panel. On a both-levers-locked opening, the facility manager typically wants to know not just whether someone credentialed, but whether the door actually latched after passage. A monitor switch that is wired but not mapped to the access control software provides no value. Confirm during commissioning that the monitoring output is connected, that the panel is reading it, and that the alarm logic for propped-open or forced-entry conditions is active.
Putting It Together at the Opening
Electrified mortise locks in a fail safe, both-levers-locked configuration are reliable and code-appropriate for a wide range of controlled openings — when the wiring, fire interface, access control output logic, and power transfer method are all coordinated before the wall closes up. The lock body is only one piece. DoorwaysPlus carries electrified mortise locksets from preferred commercial lines including Accentra, Corbin Russwin, Sargent, and Hager, along with the power transfer accessories and hardware schedule support to help contractors and facility teams get the full opening right the first time.
If you are specifying an electrified opening and need guidance on function codes, wiring configurations, or compatible power transfer hardware, contact the DoorwaysPlus team before the submittal goes out.