What Is a Maglock? Magnetic Door Locks Explained
Updated: Oct 9
The short version
A maglock (magnetic door lock) is an electromagnet fixed to the door frame and a steel plate fixed to the door. While power flows, the magnet clamps the plate and the door stays shut. Cut the power and the door is released. That makes a maglock fail safe by design, which is why it is so common on access controlled doors, communal entrances and doors on escape routes.
It is a simple, tough and reliable lock. It also comes with rules, because a door that is held by electricity has to let people out in a fire.
How does a magnetic lock work?
The lock body, a long rectangular electromagnet, mounts on the head of the frame on the opening side. A matching steel armature plate mounts on the door leaf so the two sit flat against each other when the door closes. Most maglocks run on a low voltage DC supply, commonly 12 V or 24 V, from a dedicated power supply unit.
When the access control system, intercom or push button wants to let someone through, it simply interrupts the power. The magnetic field collapses and the door can be pushed or pulled open. There are no bolts, latches or moving parts in the lock itself, which is why maglocks wear so little.
Maglocks are sold by holding force, usually quoted in kilograms or pounds. A higher rating resists a harder pull, but the fitting matters just as much: a plate that does not sit square on the magnet gives a fraction of the rated hold.
Where maglocks are used
You will find magnetic locks on:
office and shop doors controlled by fobs, cards or keypads;
communal entrance doors to blocks of flats, released by the intercom;
internal doors to comms rooms, stock rooms and staff areas;
pedestrian and vehicle gates, using weatherproof versions.
They are almost always part of a wider system: a reader or keypad on the secure side, a release button or sensor on the other, and a controller deciding who gets in. We fit them as part of the access control systems we install for businesses and residential blocks.
Fail safe vs fail secure
These two terms describe what a lock does when it loses power.
Fail safe: the door is released when power is lost. Every standard maglock works this way, because the magnet needs power to hold.
Fail secure: the door stays locked when power is lost. Some electric strikes and motorised locks work this way, while the handle or key still lets people out from the inside.
Neither is better in general. Fail safe suits doors people must be able to get out through at all times. Fail secure suits doors where security matters most during a power cut, such as a store room that is not on an escape route, provided people can always leave by the inside handle.
Maglocks on fire exits and escape routes
This is the part to get right. Article 14 of the Regulatory Reform (Fire Safety) Order 2005 says that, where necessary to keep people safe, emergency doors "must not be so locked or fastened that they cannot be easily and immediately opened by any person who may require to use them in an emergency." The Order covers workplaces and the common parts of blocks of flats, not the inside of a private house, and the duty sits with the responsible person for the premises, usually the employer, owner or managing agent.
Approved Document B gives the design guidance for new building work in England: Volume 2 covers buildings other than dwellings, and Volume 1 has the same wording for escape routes in blocks of flats (but not for flat entrance doors). Both say electrically powered locks should release in all of these situations:
if the fire detection and alarm system operates;
if there is loss of power or system error;
if the security mechanism override is activated.
It also says the security mechanism override should be a Type A call point as described in BS 7273-4, placed on the side approached by people escaping, with one on both sides if the door provides escape in either direction. In practice this is usually the green emergency door release you see beside secure doors in offices and flats.
What this means for a maglock installation:
The lock must be interfaced with the fire alarm so an alarm drops the power to it.
A Type A release must be fitted on the escape side of the door (both sides if it is used for escape in either direction).
The arrangement must match the building's fire risk assessment. Some doors have extra rules: in shops, commercial buildings and places of assembly, Approved Document B says doors on escape routes from rooms holding more than 60 people should have no locks or latches at all, or panic fastenings to BS EN 1125.
If a maglock will sit on an escape route, the fire risk assessment and whoever is responsible for it should sign off the design before it goes in.
Request to exit: getting out the normal way
Day to day, people leave through a maglocked door using a request to exit device on the inside. That is usually a push button marked "push to exit", a motion sensor that releases the lock as someone approaches, or a door handle with a built in switch. These are for convenience and are separate from the emergency override described above.
Monitored maglocks add a sensor that reports whether the door is actually shut and held. That lets the controller raise an alert if a door is propped open or forced, and it can trigger a camera on the same system. If you already have CCTV, a door event can be linked to the recording from the nearest camera.
Maglock or electric strike?
An electric strike replaces the strike plate in the frame. The door keeps its normal latch or lock, and when the strike is energised (or de-energised, depending on type) its keep swings free so the latch can pass. Strikes come in fail safe and fail secure versions.
A maglock tends to suit:
glass doors, aluminium shopfronts and doors where cutting the frame for a strike is awkward;
busy doors where wear on a latch would be a problem;
escape route doors where a guaranteed release on power loss is wanted.
An electric strike tends to suit:
timber doors that already have a good lock and handle;
doors where you want a key to work as normal as a backup;
places where a fail secure option is needed and the door is not on an escape route.
For door entry in flats, both are used. Our post on intercom and door entry systems covers how the intercom side ties in.
Pros and cons of magnetic door locks
Advantages: no moving parts, quiet, strong, easy to fit to most door types, and inherently fail safe.
Drawbacks: they need constant power, so running costs and power supply quality matter. The door is only as secure as the supply, the fire alarm link and the cabling. And the lock plate is visible, which some owners dislike on a front entrance.
If you need a maglock or a full access control door fitted, talk to our team and we will survey the door, the power and the fire alarm link before recommending a lock.
Maglock questions, answered
Do maglocks use a lot of electricity?
They draw a small current continuously while the door is held, because the magnet needs power to work. Each lock's datasheet lists its current draw, and the power supply is sized to suit every lock and reader on it.
Can a maglock be fitted to a house?
It can, but a front door on a house rarely needs one. Homeowners usually get more from a smart lock, a video intercom or a gate lock. Maglocks earn their place in flats, offices, shops and gates.
What happens to a maglock in a power cut?
A standard maglock releases, because it needs power to hold. If a door must stay held during a power cut, that changes the design and raises escape route questions, so it needs to be agreed with the fire risk assessment first.
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