Schlage Locknetics M420 Electromagnetic Single Lock - 500 Lb. Hold

The Schlage Locknetics M420 is Schlage's 500-pound single-door electromagnetic lock in the M400 Series, certified to ANSI/BHMA 156.23 Grade 1, listed under UL 1034 and UL 10C, cUL Listed, and CFSM certified for California installations. It operates at 12V or 24V DC without any voltage selection jumper: the Automatic Voltage Selection (AVS) circuit detects the power supply voltage and adjusts automatically, with polarity protection included so reversed wiring doesn't damage the unit.

The M420 is the single-door configuration. The M422 is the double-door version. For the M420 with integrated Door Status Monitor, Magnetic Bond Sensor, and Request-to-Exit button, the M420P is the accessory-equipped version. For all magnetic locks, browse our magnetic locks catalog. For power supplies and complete access control components, view our electronic hardware catalog.

What Makes the M420 Easier to Install Than Competing Maglocks

Schlage built two installation-specific features into the M420 that most competing electromagnetic locks don't include. The bayonet mounting system lets the lock body lock into position during installation while the installer drives the mounting screws, keeping both hands free. Standard electromagnetic lock installation typically requires one hand holding the lock body in position and one hand driving screws, which creates alignment problems on overhead frame installations. The bayonet mount solves that.

The armature plate pivot feature is the second one. Electromagnetic locks require precise parallel alignment between the magnet face and the armature plate for full hold-force contact. The M420's armature pivots slightly to compensate for minor door and frame imperfections, maintaining maximum face contact even when the door and frame aren't perfectly parallel. This produces consistent 500-pound hold force in real-world installations where framing isn't manufactured-standard perfect.

Schlage M420 Technical Specifications

Series: Schlage Locknetics M400. Type: Single electromagnetic lock. Hold force: 500 lbs, meets or exceeds BHMA standard. Voltage: 12V or 24V DC, automatic voltage selection (AVS). Polarity protection: Yes. Current draw: 0.75A at 12VDC; 0.38A at 24VDC. Housing: Aluminum, 628 Satin finish. Dimensions: 2-1/2" H x 9" L x 1-3/8" D. Temperature range: 0°C to 49°C (32°F to 120°F). Wire gauge: 14 to 22 AWG. Handing: Symmetrical, field-selectable. Armature: Pivot feature for alignment compensation. Mounting: Bayonet mounting system, hands-free during installation. Certifications: ANSI/BHMA 156.23 Grade 1, UL 1034, UL 10C, cUL, CFSM (California Fire State Marshall). Warranty: Limited lifetime on magnetic coil assembly.

Fail Safe Operation and Access Control Integration

Electromagnetic locks are fail-safe by design: power removed equals door unlocked. This makes them the correct specification for fire-rated egress doors where code requires the door to unlock on fire alarm activation. The access control panel de-energizes the lock on fire alarm signal, allowing free egress. For doors where fail-secure operation is required (door stays locked on power loss), an electric strike or electrified deadlatch is the correct hardware type, not an electromagnetic lock.

The M420 wires to any standard access control panel that can switch 12V or 24V DC power at 0.75A or 0.38A respectively. Timer relay, request-to-exit, and door position monitoring functions are handled by the access control panel or by external components. The M420P adds the Door Status Monitor (DSM), Magnetic Bond Sensor (MBS), and Request-to-Exit (RTD) to the lock body itself for installations where those functions need to be integrated at the lock rather than the panel.

Available Mounting Accessories

TJ420: Top Jamb Kit for inswinging doors where the magnet mounts on the door's top jamb surface rather than the frame face. HDB420: Herculite Door Bracket for frameless glass doors. 4202A: 1-1/2" x 1" angle bracket for L-bracket mounting on aluminum frames. 4204A: 1-1/2" x 2" angle bracket for greater offset. 4204F: 9" filler plate for frame cutout coverage.