What is a Mag Lock?

A mag lock, short for magnetic lock, is an electronic locking device that uses an electromagnet and a metal armature plate to hold a door closed, rather than a mechanical bolt or latch. When power is applied to the electromagnet, it creates a strong magnetic bond with the armature plate mounted on the door, keeping it securely shut until power is cut or intentionally released.

Mag locks are widely used in commercial and institutional access control systems, particularly on doors connected to card readers, keypads, or fire alarm systems, where controlled and often centralized locking is required across multiple entry points.

How Does a Mag Lock Work?

A mag lock works by generating a magnetic field strong enough to hold two metal surfaces together under continuous electrical current. The electromagnet is typically mounted on the door frame, while a matching armature plate is mounted on the door itself, aligned so the two surfaces meet when the door is closed.

As long as power flows to the electromagnet, the magnetic bond keeps the door locked, often with holding forces rated in the hundreds or thousands of pounds depending on the unit. To unlock the door, power to the electromagnet is cut — either through a request-to-exit button, access control system, keypad, or card reader — which instantly releases the magnetic hold and allows the door to open.

Key Components of a Mag Lock

A mag lock system is built from several core parts working together:

• Electromagnet unit – mounted on the door frame, generates the magnetic holding force

• Armature plate – mounted on the door, bonds to the electromagnet when locked

• Power supply – provides continuous current to maintain the magnetic lock

• Access control input (card reader, keypad, or fob reader) – authorizes power release to unlock

• Request-to-exit (REX) device – allows authorized exit from inside without triggering an alarm

• Door position sensor (on many systems) – monitors whether the door is open or closed

Because mag locks depend entirely on continuous power, they're almost always installed as part of a larger access control or fire/life-safety system rather than as a standalone lock.

What Are the Common Uses of Mag Locks?

Mag locks are commonly used in settings that require centralized, electronically controlled access, including:

• Commercial office buildings and corporate access points

• School and institutional security doors

• Server rooms, labs, and restricted-access areas

• Emergency exit doors integrated with fire alarm release systems

• Elevator lobbies and secured stairwell doors

• Gates and access-controlled entry points in multi-tenant buildings

Because mag locks are fail-safe by design (unlocking when power is lost), they're frequently required on doors that also serve as emergency exits, in order to meet fire and life-safety codes.

Main Characteristics of Mag Locks

Mag locks share several defining traits that distinguish them from mechanical and electric strike locks:

• Fail-safe operation — the door unlocks automatically if power is lost

• No moving mechanical bolt; holding force comes purely from magnetism

• Rated by holding force (commonly 600–1,500+ lbs) rather than lock grade alone

• Requires integration with access control, REX devices, and often fire alarm systems

• Mounted as a surface-applied unit rather than embedded inside the door

• Must be paired with a code-compliant exit method to avoid trapping occupants during a power outage

These characteristics make mag locks a system-level security component rather than a simple standalone door lock.

Advantages of Mag Locks

Mag locks are widely used in commercial access control for several practical reasons:

• High holding strength – many units offer very strong resistance to forced entry

• No mechanical wear points – no bolt or latch mechanism to wear out over time

• Fail-safe for life safety – automatically unlocks during a power outage, supporting emergency egress

• Easy integration – works seamlessly with card readers, keypads, and centralized access control systems

• Scalable across multiple doors – well-suited for buildings managing many access points from one system

Because mag locks combine high holding force with fail-safe emergency operation, they remain a standard choice for commercial access control systems that need both strong security and code-compliant emergency exit function.