What This Guide Covers and Who It Helps
This article explains how electromagnetic locks (maglocks) must be wired to connect with a building fire alarm system. It is written for commercial electrical contractors, low-voltage integrators, facility managers overseeing access control upgrades, and architects reviewing riser diagrams for code compliance. Whether you are wiring a school entrance, a hospital corridor door, or an industrial access point, the fire alarm release path is the circuit that gets installations rejected at inspection most often -- and the one that is most frequently drawn wrong on shop drawings.
What Is a Maglock Fire Alarm Release Circuit?
A maglock (electromagnetic lock) holds a door closed through magnetic attraction between a lock body mounted in the frame header and an armature plate mounted on the door. It is fail-safe by design: the door is locked only while the lock is energized, and it releases immediately the moment power is interrupted. This makes it suitable for controlled-egress applications -- but it also means that any loss of power, including a fire alarm signal, will release the lock and allow the door to open freely.
The fire alarm release circuit is the wiring path that guarantees this happens: when the building fire alarm panel activates, a relay in that path cuts power to the maglock, releasing the door regardless of any other access control state.
Why the Fire Alarm Connection Is Not Optional
Model codes are explicit. Even when a maglock system uses a compliant primary release method -- a listed switch built into the door hardware, a request-to-exit (REX) motion sensor, or a keypad-controlled access system -- the fire alarm interface is still required on fire-labeled doors. A maglock on a fire-rated door assembly that has no fire alarm release path shown on the wiring diagram is a code violation and will fail inspection.
Common settings where this matters most:
- Schools: Entrance vestibules and interior corridor doors controlled by access control for lockdown capability
- Healthcare: Stairwell access doors, secured unit entries, and corridor separations on fire-rated assemblies
- Retail and commercial: Back-of-house doors, server room entries, and loading dock access points
- Industrial: Controlled production areas where maglocks are used in place of electrified locksets
The Two Distinct Release Paths -- and Why Both Must Be Wired
A compliant maglock installation on a fire-rated or egress-controlled door requires two independent release paths, not one:
1. Primary Egress Release (User-Initiated)
This is what releases the lock when a person needs to exit under normal conditions. Acceptable primary release methods under current model codes include:
- A listed switch built directly into the door hardware (such as a panic bar or lever trim) that directly interrupts lock power -- no fire alarm connection required for this function alone
- A request-to-exit (REX) passive infrared sensor detecting approach -- acceptable as a supplemental device but not accepted as the sole primary release by model codes
- A push-button egress switch within 5 feet of the door -- also not permitted as the only release method
Important: CPU-routed switch signals -- where the controller software processes the signal before cutting power -- are not compliant as primary release. Direct power interruption is required.
2. Fire Alarm Release (Automatic, System-Initiated)
This is the circuit that must be wired regardless of the primary release method chosen. The fire alarm panel's output dry-contact connects to a fire alarm relay module (sometimes called a PDFT relay or fire relay) within the power supply or as a standalone module. When the alarm activates:
- The relay opens, cutting 12 VDC or 24 VDC power to the maglock
- The maglock releases immediately
- The door can be pushed open freely for egress
- The door remains unsecured until the fire alarm system is reset and power is restored
Wiring the Fire Relay: What the Drawing Has to Show
Inspection rejection often traces back to incomplete or incorrect riser diagrams. A compliant point-to-point wiring diagram for a maglock with fire alarm integration must include:
- The fire alarm panel shown and connected to the fire relay (or FAR module) -- not implied, not missing
- The power supply model specified with its fire relay input terminals labeled
- Wire type labeled on every run (not just "wire" -- specify gauge and conductor type)
- The maglock voltage confirmed (factory default is typically 24 VDC; verify the voltage selection switch setting before wiring -- some units have a slide switch for 12 V / 24 V selection in the wiring compartment)
- LED status lead connections shown where the maglock model includes them (typically Red lead to V+, Black lead to V-)
- The door position switch (DPS) shown sensing door position at the frame -- not on the door face
- Any REX device shown within 5 feet of the door per IBC access-controlled egress requirements
If any of these elements are missing from the drawing, flag it before rough-in. Correcting the wiring after walls are closed is far more expensive than catching it on paper.
Fire-Rated Door Assemblies: The Latching Requirement That Catches Specifiers Off Guard
One of the most common field problems: a fire-labeled door is fitted with a maglock as the only means of keeping the door closed. This is not compliant. A maglock does not latch. NFPA 80 requires positive latching on all fire door assemblies. A maglock must be paired with passage-function hardware that provides a positive latch -- the maglock provides the access-controlled hold, the latch hardware provides the fire-rated positive closure required by the listing.
Failing to include latching hardware on a fire-rated maglock opening is one of the most cited deficiencies in annual fire door assembly inspections.
Common Wiring Errors to Catch Before Inspection
- Fire alarm panel shown on the drawing but not connected to the power supply fire relay
- CAT5/6 cable used for lock power runs (data cable -- not rated for lock power)
- REX or motion detector shown as the only release method (non-compliant)
- Push button shown as the sole egress release (prohibited by all model codes)
- Maglock body shown mounted on the door face rather than in the frame header
- No junction boxes shown at the door -- implying a direct home run without transition points
- Voltage mismatch between power supply output and maglock voltage setting
Getting the Right Hardware Package Together
A complete, code-compliant maglock installation at a controlled-egress door typically involves:
- The maglock body and armature plate
- A dedicated power supply with integrated or add-on fire relay module
- A door position switch (DPS) at the frame
- A REX device (motion sensor or push-plate switch) within 5 feet of the door
- Passage-function lockset or exit device providing positive latching (fire-rated assemblies)
- Access credential device (keypad, card reader, or key switch) at the appropriate mounting height per ADA requirements (max 48 inches AFF)
DoorwaysPlus carries electromagnetic lock hardware, power supplies, door position switches, and the complementary hardware components needed to build a compliant maglock opening package. If you are working from a hardware schedule or a riser diagram that needs a second set of eyes, our team can help you identify gaps before they become field problems.
Browse maglock components and access control hardware at DoorwaysPlus.com, or contact us directly to get a complete opening package quoted for your project.