Types of Electric Locks for Access Control: Maglock vs Drop Bolt vs Electric Strike

The main types of electric locks used in access control are the electromagnetic lock (maglock), the electric drop bolt, the electric strike, the electrified mortise lock and the electromagnetic shear lock. Maglocks and shear locks are always fail-safe and suit glass, aluminum and retrofit doors; strikes and mortise locks keep a mechanical latch with free egress and suit timber, hollow-metal and fire-rated doors; drop bolts cover frameless and double-acting glass. Choose by door construction first, then egress requirements, then what must happen when power fails.

Electric lock types at a glance

Lock type	Mounts on	Power-loss state	Egress from inside	Best fit	Watch out for
Electromagnetic lock (maglock)	Magnet on frame header, armature plate on door	Fail-safe only	Power must be cut by the approved egress-release arrangement	Glass, aluminum storefront and retrofit doors	Visible hardware; strict code conditions on egress doors
Electric drop bolt	Frame header; bolt drops into a strike on the door top	Fail-safe or fail-secure (per model)	Approved electrical release, or mechanical free egress; an inside key override is insufficient	Frameless and double-acting glass doors	Alignment; start-up current surge
Electric strike	Door jamb, replacing the strike plate	Fail-secure or fail-safe (often field-selectable)	Free, through the lockset’s inside lever	Timber and hollow-metal doors with a lockset	Frame cutting; latch preload
Electrified mortise lock	Inside the door, in the lock case	Fail-safe or fail-secure (often field-selectable)	Free, through the inside lever	High-traffic and fire-rated doors	Door prep; power transfer hinge
Electromagnetic shear lock	Concealed in header; armature mortised into door top	Fail-safe only	Power must be cut by the approved egress-release arrangement	Double-acting doors, concealed installs	Door must come to rest precisely aligned

Maglock. An electromagnet on the header pulls a steel armature plate on the door. It provides no mechanical latch and holds only while current flows. Single-door units are commonly rated around 280 kg (600 lb) of holding force, with larger models for heavy or exposed doors. Many run on 12 or 24 V DC selected by jumper, and some add a lock-status output. See our range of magnetic locks and brackets.

Electric drop bolt. A solenoid or motor drives a bolt from the header down into a strike plate on top of the door. Many units sense door position through a magnet in the strike plate and throw the bolt only once the door has closed, after an adjustable relock delay. Browse electric bolt locks.

Electric strike. It replaces the strike plate in the jamb. The door’s existing lockset still latches; the strike controls a pivoting keeper that either holds the latch or lets it swing past.

Electrified mortise lock. The electric function sits inside the lock case: applying or removing power connects the outside lever to the latch. On a model designed for mechanical free egress, the inside lever retracts the latch independently of the electric entry-control function. Verify the lock function and required exit hardware.

Shear lock. This is an electromagnetic lock mortised into the header, with its armature set into the top edge of the door. When energized, the armature is pulled up and interlocks with the magnet body, so the lock resists the door’s sideways (shear) movement rather than a direct pull.

Maglock vs electric strike

This is the most common decision on a standard single-leaf door. The two locks differ in how they hold, how people get out and what happens in an outage.

Factor	Maglock	Electric strike
How it holds	Magnetic attraction between magnet and armature	The door’s own latch, held by the strike keeper
Power-loss state	Always unlocked (fail-safe)	Locked (fail-secure) or unlocked (fail-safe), per model or setting
Egress	Approved electrical release, such as sensor-release or door-hardware-release arrangement	Suitable inside lever / exit device retracts the latch mechanically
Installation	Surface mount on the header; no frame cutting	Jamb cut-out; must match the lockset latch and door gap
Fire-rated doors	Does not provide positive latching; confirm permitted assembly and release arrangement	Use the exact fire-listed strike / door combination and permitted fail mode
Current draw	Continuous while locked	Fail-secure: only while unlocked. Fail-safe: continuous
Main limitation	Releases on power loss unless battery-backed	Security depends on latch, lockset and frame; preload can block release

The maglock’s catch is egress. Because it has no latch, the only way out is to remove its power, so building codes set conditions. In the US, NFPA 101 and the IBC allow electrically locked egress doors only under specific arrangements. One example is sensor release: a sensor on the egress side unlocks the door as someone approaches, a manual release device near the door cuts lock power directly (independent of the access control electronics) and keeps the door unlocked for at least 30 seconds, and the lock also releases on fire-alarm or sprinkler activation and on loss of power. Another is door hardware release, where a switch inside the lever or exit device cuts lock power as the occupant operates it. Pair the lock with exit buttons and REX sensors that match the arrangement your authority having jurisdiction (AHJ) accepts, and confirm which code edition applies.

In Europe, electrically controlled exit systems on escape routes fall under EN 13637. Fire doors are tested as complete assemblies under EN 1634-1, so any lock you add must be covered by that door’s fire test evidence or certification.

An electric strike sidesteps most of this. With a suitable free-egress lockset, the inside lever retracts the latch independently of the strike, so egress is mechanical. That is why strikes and electrified mortise locks dominate on offices, corridors and fire doors, while maglocks dominate on glass and aluminum storefronts where cutting a jamb is impractical. One strike-specific trap: if door seals, a closer, wind or air pressure push the latch hard against the keeper, a standard strike may not release. Specify a strike rated for preload on those openings.

Drop bolt vs maglock on glass doors

Glass doors rarely carry a lockset, so the choice usually comes down to a maglock or a drop bolt. Both are available fail-safe; the difference is mechanical.

A maglock on glass mounts on the header, with the armature fixed to the glass by a clamp bracket on frameless doors. The armature must self-align and sit flat; follow the release circuitry and mounting instructions to avoid residual holding or delayed release. It does need the door to close flat against the magnet face, so it suits single-swing doors with a closer. Our maglock bracket guide explains which bracket fits which swing direction.

A drop bolt engages a strike on the top of the door, so it does not care which way the door swings. That makes it the usual choice for double-acting glass doors on floor springs, which have no stop for a magnet to seat against. The trade-off is precision: the bolt must land in the strike hole, so the door has to come to rest centered and still. Door-position sensing and relock delay help, but a well-adjusted floor spring or closer matters as much as the lock.

Other differences to weigh:

• Appearance: drop bolts are usually mortised into or mounted flush with the header; maglocks are surface-mounted and visible.
• Alignment tolerance: maglocks forgive sagging doors better; drop bolts jam or fail to throw when the door is off-center or under side load.
• Power pattern: maglocks draw steady current while locked; drop bolts draw a surge each time the bolt moves, then a lower holding current.
• Holding failure: a maglock loses force when the armature cannot sit flush (dirt, damaged plate, door sag); a drop bolt fails when the bolt misses the strike.
• Glass fixing: both need clamps sized to the glass thickness. Tempered (toughened) glass cannot be drilled after tempering, so the clamp carries the hardware.

Fail-safe and fail-secure by lock type

A fail-safe lock unlocks when power is removed; a fail-secure lock stays locked. The terms describe the secure (outside) side of the door. With strikes and mortise locks, the inside lever gives free egress either way. Our fail-safe vs fail-secure guide covers door-by-door choices in more depth.

• Maglock and shear lock: fail-safe only. An electromagnet cannot hold without current. If the door must stay secure during an outage, battery-back the supply or choose a different lock.
• Electric drop bolt: sold as fail-safe or fail-secure models. A fail-secure bolt must not obstruct required egress during power loss. An inside key override is not mechanical free egress: select approved hardware that opens from inside without a key, tool or special knowledge, or use a different permitted arrangement. An outside key override serves entry.
• Electric strike: both; many are field-reversible. Check the exact fire listing and permitted mode; many strike fire ratings apply only to fail-secure operation.
• Electrified mortise lock: both, often field-selectable. Fire-rated stair doors that must allow re-entry on alarm typically use a fail-safe electrified lockset: the outside lever is freed while the latch stays engaged, so the fire door remains latched. A fail-safe strike would leave it unlatched.

A power-interruption release unlocks power-to-lock hardware only. Other alarm functions can command powered unlocking where the design requires it; do not assume cutting power will unlock a fail-secure lock. Required free egress must work through the selected mechanical or approved electrical arrangement.

Power and wiring differences

Lock	When it draws current	Controller relay contacts	Suppression
Maglock	Continuously while locked	NC + COM in the dry-relay example below	Exact manual; an added diode can be prohibited
Drop bolt, fail-safe	Surge on each throw, then holding current while locked	NC + COM, or the lock’s own control input	Per datasheet; many include it
Drop bolt, fail-secure	Surge on retraction, then holding current while unlocked	NO + COM, or the lock’s own control input	Per datasheet
Electric strike, fail-secure	Only while unlocked	NO + COM in the dry-relay example	Manufacturer-specified suppression / accessory
Electric strike, fail-safe	Continuously while locked	NC + COM in the dry-relay example	Manufacturer-specified suppression / accessory
Electrified mortise lock	Depends on mode; motor-driven types draw briefly	NC or NO, matching the mode	Per datasheet; wired through a power transfer hinge

Relay contacts. These examples assume dry contacts with the relay de-energized while locked and energized to unlock. NC and COM are then connected while locked, so a fail-safe lock stays powered. Granting access energizes the relay, opens NC and releases the lock. A fail-secure lock on NO and COM gets power only while the relay operates. Reversed logic changes this; powered outputs need the manufacturer’s diagram. On Altronix ACM powered outputs, COM is negative, not the dry-contact supply-positive common.

Suppression. Use the exact lock / output instructions. Securitron M32/M62/M82B locks prohibit a parallel reverse diode because it interferes with quick release; HES offers specified surge-protection accessories for its strikes. Do not substitute a generic diode or arbitrary MOV for the approved arrangement.

Voltage and cabling. Most access control locks run on 12 or 24 V DC, and many maglocks are dual-voltage by jumper. Many dual-voltage locks draw less current at 24 V, reducing cable drop; the exact ratio depends on the model. Locks inside the door leaf (mortise locks, electrified exit devices) need a power transfer hinge or door loop to get cable across the hinge side.

Power supply. Separately protected lock and electronics outputs can improve fault isolation. Where alarm release is required, configure the approved interface to interrupt battery-backed power-to-lock outputs. Size for actual operating, simultaneous peak and standby conditions, and follow fuse / PTC ratings. The magnetic lock wiring diagrams show the connections, and our guide to sizing an access control power supply covers current budgets, drop bolt surges and battery backup.

Which lock for which door

Door	Usual first choice	Why
Framed aluminum or glass storefront, out-swing	Maglock, 280 kg (600 lb) class, on the header	No frame cutting; specify the accepted independent egress-release arrangement
In-swing door without a lockset	Maglock with a ZL bracket	Bracket brings the armature to the magnet face
Frameless glass, single swing	Drop bolt with glass-door strike clamp, or maglock with glass clamp bracket	Neither needs holes in tempered glass
Frameless glass, double-acting on a floor spring	Fail-safe drop bolt or shear lock	Engages from above regardless of swing direction
Timber or hollow-metal office door with a lever set	Electric strike, usually fail-secure	Free egress through the lever; stays locked in an outage
Fire-rated corridor door	Fire-rated fail-secure strike or electrified mortise lock	Door stays positively latched; confirm against the door’s label or certificate
Stair door that must unlock for re-entry on alarm	Fail-safe electrified mortise lockset	Frees the outside lever while the latch stays engaged
Server room or stock room	Fail-secure strike or electrified mortise lock	Secure during outages; occupants exit by lever

Before ordering, walk each opening with this checklist:

• Door material and construction: framed or frameless glass, aluminum, timber, hollow metal; glass thickness if applicable
• Swing: in-swing, out-swing or double-acting; single or double leaf
• Is it a required egress door, and which code and edition does the AHJ enforce?
• Is the door fire-rated, and what does its label or certificate allow?
• Required power-loss state for this door: fail-safe or fail-secure
• Existing lockset or exit device to keep or replace
• Cable path: header access, and a power transfer hinge for in-door locks
• Lock voltage (12 or 24 V DC), available supply capacity and battery backup
• Monitoring: door status sensor and lock or bolt status output
• Environment: indoor or outdoor, temperature range, exposure to water
• Brackets, glass clamps and a closer or floor spring that returns the door reliably
• Required product / system listings for the accepted arrangement, such as UL 294 or UL 1034 where applicable; these do not replace door-assembly approval

Next steps

Send us your door schedule with door type, swing, fail mode and lock voltage. We will match maglocks or drop bolts with the right brackets, exit buttons and power supplies, confirm compatibility with your controller, and ship samples for a trial door if you need them. Request a quote and we will reply within 24 hours.

Sources

• HES: fail-safe versus fail-secure and mechanical egress; 1500 series fire listing.
• ICC: electrical egress-locking arrangements; UL: locking configurations and free-egress principles.
• Securitron M32/M62/M82B installation manual: quick release and suppression; HES SMART Pac III.
• Altronix ACM manual: powered and dry output terminals.
• BSI: EN 13637 scope; EN 1634 series.