A technical and code-compliance guide to Securitron electromagnetic locks covering holding force ratings, life safety code requirements, delayed egress provisions, power supplies, and bond sensor monitoring — available through CDF Distributors via ASSA ABLOY distribution.
This guide answers: How do Securitron electromagnetic locks work and what are the code requirements for mag lock installations?
How Electromagnetic Locks Work
An electromagnetic lock (mag lock) uses an electromagnet mounted on the door frame header and an armature plate mounted on the door leaf. When the electromagnet is energized, it creates a magnetic bond between the magnet and the armature plate that holds the door closed. The holding force of this bond ranges from 600 pounds to 1,500 pounds depending on the magnet size and power consumption. When the access control system removes power from the electromagnet, the magnetic bond releases instantly and the door swings freely.
Unlike mechanical locks that use a latchbolt or deadbolt to physically engage a strike, electromagnetic locks have no moving parts in the locking mechanism. There is no latch, no bolt, and no strike plate. The door is held closed entirely by magnetic force. This design eliminates mechanical wear, reduces maintenance requirements, and provides a locking device with an indefinite mechanical life span.
Securitron, an ASSA ABLOY brand, is one of the most widely specified electromagnetic lock manufacturers in the commercial security industry. Securitron mag locks are used in access control applications ranging from office entry doors to high-security government facilities. The product line includes surface-mounted magnets, shear locks (concealed magnets), and specialty configurations for gates, sliding doors, and cabinet locks.
Holding Force Ratings and Selection Criteria
Securitron electromagnetic locks are rated by holding force, measured in pounds of force required to pull the armature plate away from the energized magnet. The three standard holding force categories address different door sizes, security levels, and application requirements.
The following summary provides selection guidance for each holding force category based on door type and security requirements.
- 600-pound holding force: Suitable for interior doors, office entry doors, and lighter-duty applications. The 600-pound rating provides adequate holding force for standard 3-foot-wide hollow metal or wood doors in normal use. This is the most commonly specified rating for interior access control applications where the primary concern is controlled access rather than forced-entry resistance.
- 1,200-pound holding force: The standard specification for most commercial exterior doors, stairwell doors, and medium-security applications. The 1,200-pound rating provides sufficient force to resist casual forced-entry attempts and withstand the mechanical stresses of high-traffic doors. This is the most commonly specified rating across all commercial access control applications.
- 1,500-pound holding force: Specified for high-security applications, oversized doors, double doors, and applications where wind load or other external forces act on the door. The 1,500-pound rating is used in government facilities, detention areas, data centers, and any opening where maximum holding force is required.
Holding Force and Door Size Considerations
The effective holding force of an electromagnetic lock decreases as the distance from the pivot point (hinge) to the magnet increases. For standard 3-foot-wide doors, the magnet is typically mounted on the frame header directly above the lock stile (the side opposite the hinges), maximizing the mechanical advantage. For wider doors (4 feet or greater), the lever arm is longer and the effective holding force at the door edge is reduced. In these cases, a higher holding force rating or dual magnets may be required.
Door weight also affects mag lock selection. Heavy doors — such as bullet-resistant doors, lead-lined doors, or solid-core hardwood doors — place greater demands on the magnet-armature bond due to inertia and the forces generated when the door is pulled against the magnet. For doors exceeding 200 pounds, verify the mag lock manufacturer's recommendations for minimum holding force.
Life Safety Code Requirements for Electromagnetic Locks on Egress Doors
Electromagnetic locks on doors that serve as required means of egress are subject to strict life safety code requirements under NFPA 101 (Life Safety Code) and the International Building Code (IBC). Because mag locks are inherently fail-safe devices — they release when power is removed — they are generally permitted on egress doors. However, the method of release and the specific code provisions that apply depend on the occupancy type and the door's role in the egress system.
The fundamental code requirement is that occupants must be able to exit through a mag-locked door without specialized knowledge, keys, tools, or special effort. The specific provisions that satisfy this requirement fall into several categories, each with its own set of conditions.
Sensor-Release Electromagnetic Locks (NFPA 101 Section 7.2.1.5.5)
Sensor-release mag locks use a request-to-exit (REX) sensor to detect when an occupant approaches the door from the egress side. The sensor — typically a passive infrared (PIR) motion detector or a door-mounted push button — sends a signal to the access control system, which de-energizes the mag lock and allows the door to open freely. This is the most common configuration for mag locks on egress doors in most commercial occupancies.
Code requirements for sensor-release mag locks include: the sensor must detect an occupant approaching from the egress side and release the lock before the occupant reaches the door; loss of power to the sensor or the lock must result in immediate release of the lock; the door must be equipped with a sign that reads 'PUSH UNTIL ALARM SOUNDS — DOOR CAN BE OPENED IN 15 SECONDS' or similar language approved by the AHJ if the sensor release is used in conjunction with a delayed egress system.
Delayed Egress Electromagnetic Locks (NFPA 101 Section 7.2.1.6.1)
Delayed egress provisions allow a mag lock to remain energized for up to 15 seconds after an occupant initiates an egress attempt. When the occupant pushes on the door or activates the exit device, an irreversible process begins: an alarm sounds immediately, and after the delay period (not exceeding 15 seconds), the lock releases automatically. The lock must also release immediately upon activation of the fire alarm system, sprinkler system, or loss of power.
Delayed egress is permitted in buildings that are fully protected by either an approved automatic sprinkler system or an approved automatic fire detection system. The delay is intended to deter unauthorized removal of merchandise (retail), patients (healthcare), or inmates (pre-arraignment detention) while maintaining life safety. A sign at the door must instruct occupants on the egress procedure.
Securitron manufactures dedicated delayed egress mag lock controllers that integrate the timer, alarm, fire alarm interface, and power supply into a single device. These controllers simplify code compliance by providing all required functions in a pre-configured package.
Fire Alarm and Sprinkler System Interface
All electromagnetic locks on egress doors must release immediately upon activation of the building's fire alarm system. This is a non-negotiable code requirement. The fire alarm system interface is typically accomplished through a normally-closed relay contact in the power supply circuit. When the fire alarm activates, the relay opens, removing power from the mag lock and releasing the door.
In buildings with automatic sprinkler systems, activation of the sprinkler waterflow switch must also release all mag locks in the affected area. This provides a redundant release mechanism in case the fire alarm panel interface fails.
Fire-Rated Door Considerations for Mag Lock Installations
Electromagnetic locks may be installed on fire-rated door assemblies, but specific listing requirements apply. The mag lock must not interfere with the fire-rated door's ability to close and latch positively during a fire event. Because mag locks release when power is removed (and the fire alarm interface removes power during a fire), the door must have an independent means of positive latching — typically a mechanical lock, latch, or fire exit hardware that engages when the door closes.
Fire-rated openings in commercial construction carry ratings of 20 minutes, 45 minutes, 60 minutes, 90 minutes, and 180 minutes. The mag lock installation must not compromise any of these ratings. The magnet housing and armature plate must not penetrate the fire-rated door or frame in a way that reduces the fire resistance of the assembly. Surface-mounted mag locks that do not require through-penetrations are generally acceptable on fire-rated assemblies when listed for the purpose.
Coordination between the electromagnetic lock, the fire-rated door closer, and the positive-latching hardware is critical. The door closer must close the door with sufficient force to engage the mechanical latch after the mag lock releases during a fire alarm. The door closer grade and spring size must be specified to overcome any friction, air pressure, or stack effect forces that might prevent the door from closing and latching.
Power Supplies for Electromagnetic Locks
Securitron electromagnetic locks operate on 12 VDC or 24 VDC, depending on the model. The power supply must provide sufficient current to maintain the magnet at full holding force while also powering any auxiliary devices (LED indicators, bond sensors, door position switches). Securitron manufactures dedicated power supplies designed to pair with their mag lock product line.
Battery backup is a critical consideration for mag lock power supplies. Because mag locks are fail-safe (they release when power is removed), a power failure releases every mag lock in the building unless backup power is provided. For security-critical applications, the power supply should include battery backup with sufficient capacity to maintain the mag locks for a defined period — typically 4 to 8 hours for commercial applications.
Filtered and regulated power supplies are required for electromagnetic locks. Unfiltered or poorly regulated power can cause the magnet to buzz audibly, generate heat, and reduce holding force. Securitron power supplies include filtering and voltage regulation specifically matched to their mag lock product line.
Bond Sensor Monitoring
A bond sensor (also called a magnetic bond sensor or door status sensor) is an integrated monitoring device in the mag lock that detects whether the armature plate is in full contact with the electromagnet face. When the armature is properly seated against the magnet, the bond sensor reports a secure condition to the access control panel. When the armature separates from the magnet — either because the door opened or because the armature is misaligned — the bond sensor reports an unsecured condition.
Bond sensing provides a more reliable door status indication than a standard magnetic door contact. A magnetic contact mounted on the frame can report the door as closed even if the armature plate is not fully seated against the magnet (due to misalignment, debris, or a bent armature bracket). The bond sensor detects actual magnetic bond, not just door position.
Securitron mag locks are available with integrated bond sensors that provide a dry contact output for connection to the access control panel. The bond sensor signal can be used to generate alarms for door forced open, door held open, and door ajar conditions. For high-security applications, bond sensing is considered a mandatory specification.
How CDF Distributors Supplies Securitron Electromagnetic Locks
Within CDF's ProBuilder tool, electromagnetic locks can be specified as part of a complete door, frame, and hardware assembly for access-controlled openings. ProBuilder allows users to configure the door type, frame type, mechanical hardware (closer, exit device), and the electromagnetic lock with its associated power supply and monitoring devices. This integrated configuration approach ensures compatibility between all components of the opening.
For projects involving life safety code review, CDF's sales engineering team provides specification support. This includes verifying that the selected mag lock configuration complies with the applicable NFPA 101 or IBC provisions for the occupancy type, confirming fire alarm interface requirements, and ensuring that fire-rated assemblies include the required positive-latching hardware in addition to the electromagnetic lock.
Configure Your Door Assembly
CDF's ProBuilder tool allows contractors and facility managers to configure complete door, frame, and hardware assemblies online. During configuration, you can select the specific components discussed in this guide and receive an instant quote.
For assistance or to order a complete door assembly, call (855) 769-9895 or email sales@cdfdoors.com. CDF's sales team is available to help you specify the right components for your project.
Frequently Asked Questions
What is the difference between an electromagnetic lock and an electric strike?
An electromagnetic lock uses magnetic force between an electromagnet and an armature plate to hold the door closed. It has no moving parts and releases when power is removed (fail-safe). An electric strike replaces the standard strike plate and electronically releases the latchbolt of an existing mechanical lock. Electric strikes can be fail-safe or fail-secure.
What holding force rating should be specified for a standard commercial door?
A 1,200-pound holding force is the standard specification for most commercial access control applications. Use 600 pounds for light-duty interior doors and 1,500 pounds for high-security, oversized, or wind-loaded doors.
Are electromagnetic locks allowed on fire-rated doors?
Electromagnetic locks may be installed on fire-rated doors provided the installation does not compromise the fire rating. The door must have an independent positive-latching device. Fire-rated openings carry ratings of 20, 45, 60, 90, and 180 minutes. The mag lock must release upon fire alarm activation and the door must close and latch mechanically.
What happens to mag locks during a power failure?
Electromagnetic locks are fail-safe devices that release when power is removed. During a power failure, all mag locks without battery backup release immediately. For security-critical applications, battery backup power supplies maintain the mag locks for 4 to 8 hours during an outage.
What code requirements apply to mag locks on egress doors?
NFPA 101 and IBC require that occupants can exit through a mag-locked egress door without keys, tools, or special knowledge. This is achieved through sensor-release (motion detector unlocks the mag lock) or delayed egress (15-second maximum delay with alarm). All mag locks on egress doors must release upon fire alarm activation.
What is a bond sensor and why is it important?
A bond sensor is an integrated device in the mag lock that detects whether the armature plate is in full magnetic contact with the electromagnet. It provides more reliable door status than a standard magnetic contact because it confirms actual magnetic bond rather than just door position. Bond sensing is considered mandatory for high-security applications.
Can CDF supply Securitron mag locks as part of a complete door assembly?
CDF supplies Securitron mag locks through ASSA ABLOY distribution. ProBuilder allows configuration of complete door assemblies including the mag lock, power supply, and monitoring devices. CDF's sales engineering team provides code compliance support for mag lock applications on egress and fire-rated doors.
What is delayed egress and when is it permitted?
Delayed egress allows a mag lock to remain locked for up to 15 seconds after an egress attempt. An alarm sounds immediately and the lock releases after the delay. Delayed egress is permitted in buildings with automatic sprinkler or fire detection systems and is commonly used in retail, healthcare, and pre-arraignment detention.
About This Guide
This guide reflects CDF Distributors' standard specifications and field-tested recommendations used by commercial contractors nationwide. The information is provided for specification and selection purposes. Always verify requirements with the Authority Having Jurisdiction (AHJ) for your project location.
For questions or to order a complete door assembly, contact CDF at (855) 769-9895 or sales@cdfdoors.com. Configure your assembly online at ProBuilder: cdfdistributors.com.
