How a magnetic lock holds a door
A magnetic lock, usually called a maglock, is built from two parts. One is an electromagnet, a coil of wire around an iron core, mounted at the top of the door frame. The other is a flat steel plate called an armature, mounted on the door so that it meets the magnet face when the door is closed. When electricity flows through the coil, it becomes a strong magnet and pulls the plate against it. The door is held shut by magnetism.
When the electricity stops, the magnetism stops and the plate is released. There is no bolt, no latch and no key. The door is simply held, or not held, depending on whether the power is on. This makes a maglock naturally fail-safe: if power is lost, the door unlocks.
Maglocks are popular for several reasons. They have no moving parts to wear out. They suit doors where a strike or a mortise lock is difficult to fit, such as glass doors in aluminum frames. They can hold a door against considerable force when properly installed and aligned. And they are easy to control from a card reader, a keypad, a button or a building system.
They are also the hardware most associated with safety concerns. Because there is no latch to retract, a person inside cannot simply turn a handle and leave. Exit must come from something else: a button, a sensor, a manual release or a connection to the fire alarm. That is why this page is about the rules for exits as much as the lock itself. The overview in the page on access control for small business doors introduces the wider system.
Why egress rules are strict
In a fire, people need to leave quickly and without confusion. They may be frightened, the room may be dark or full of smoke, and they may not know the building. A door that requires a card, a key, a PIN or insider knowledge to open from inside can trap them. Building and fire regulations exist because people have been harmed by locked exits in the past.
As a result, doors that are part of the path of exit generally must be openable from the inside by a simple action, without keys, tools or unusual effort, and without needing to know how. The details differ depending on the type of building, how many people it holds and the local authority. What does not change is the principle: the exit must work every time, in every condition, for every occupant.
A maglock on an exit route has to meet that principle by other means. Many installations use a combination: a push button or motion sensor at the door that cuts power to the magnet, a manual release button that cuts power directly with no dependence on software, and a connection to the fire alarm that drops power when the alarm sounds. In addition, power failure releases the door by the nature of the lock.
Some jurisdictions allow unusual arrangements such as delayed egress, where a door releases after a short delay when someone pushes it, with an alarm and conditions about where it may be used. These arrangements are tightly controlled, require listed hardware and are approved by the authority having jurisdiction. They are not something a business can design for itself.
A locksmith is not the authority on these rules. The people responsible are the fire marshal and the building department in your area, and a design professional where one is involved. A locksmith or installer can fit hardware within what is approved, and can explain how the hardware works, but should not claim to override or interpret rules for your building. When in doubt, ask the authority.
The release arrangements a maglock door usually has
A well designed maglock door has several ways to release, each independent. The first is a request to exit sensor or push button on the inside. When someone approaches or presses it, power to the magnet is cut for a short time, the door releases and the person leaves. This is the normal, everyday release.
The second is a manual emergency release, often a green button in a protective housing near the door, that cuts power to the maglock directly. It is wired so that pressing it removes power regardless of what the software or controller is doing. It exists as a backup in case the sensor fails or the person does not know how the sensor works. It is clearly labeled.
The third is a connection to the fire alarm system. When the alarm sounds, power to the maglocks on exit routes is removed, so doors release automatically. This is normally arranged by a fire alarm contractor or by the system installer with the alarm contractor, and it needs testing. A maglock that does not release when the alarm sounds is a serious defect.
The fourth is power loss. If mains power fails and the battery backup is exhausted, the magnet loses power and the door releases. This is an inherent behavior, but it means a business must think about security during an outage, since doors may be unlocked. Some businesses accept that. Others choose different hardware for doors where staying locked during an outage is vital.
Each of these releases should be tested at installation and at regular intervals. A business that relies on a maglock for a door on an exit route should keep a record of tests. The page on card reader door installation planning describes the power and fail state side in more detail.
- Request to exit sensor or button on the inside of the door
- Manual emergency release that cuts power directly
- Connection to the fire alarm so doors release when it sounds
- Release on power loss as a built in behavior
- Regular testing of every release, recorded in a log
Where a maglock fits and where it does not
Maglocks suit certain doors well. A glass door in an aluminum frame, where a strike will not fit, is a classic case. An interior door in an office where the lock's job is to control entry in one direction, with the exit arrangements provided by a sensor and a button, is another. A door with an unusual shape or one that needs to hold against pushing can benefit from the holding power of a magnet.
They fit less well in some settings. A door that must resist forcing from outside in an area with high risk may be better served by a mechanical lock with a bolt, since a maglock's holding depends on alignment and power, and forceful attacks on poorly installed maglocks can succeed. Doors on routes that serve large numbers of people may be subject to additional restrictions, and some uses may not permit a maglock at all.
Maglocks are also not recommended for outdoor doors without protection, since weather, salt air and humidity can corrode the armature and the magnet face and impair holding. If a maglock must be used outside, the installer should choose a model suitable for exposure and protect it properly.
Another consideration is the frame and door. A maglock needs a rigid frame at the top to carry the magnet and a door that stays aligned. A door that sags or twists reduces contact between the magnet and the plate, weakening the hold. A technician checks the door and frame before recommending a maglock, and may recommend repairs first. See storefront door lock repair for how pivots and closers affect alignment.
Finally, think about double doors. Maglocks can hold a pair of doors, using a magnet on each leaf or dedicated hardware for the meeting stiles. The pair raises extra alignment issues, and the exit arrangements must cover both leaves. This is a situation where an on-site design visit pays off.
Installation details that make the difference
Several details decide whether a maglock works well. Alignment is first. The armature plate must meet the magnet face squarely, with no gap and no tilt. A plate that is a little off holds weakly, and a door that can be pulled or flexed against the lock loses security. Armature plates are usually mounted on a sprung or pivoting assembly so that they seat flat against the magnet, and the installer adjusts them with care.
Mounting style matters. Surface mounted maglocks are fixed to the face of the frame header and the door, and are easy to see. Concealed or shear style maglocks are mounted inside the frame and door edge, and look cleaner, but need more preparation and may not suit every door. The choice affects appearance, difficulty and strength.
Power is next. A maglock needs steady direct current at its rated voltage. Voltage that sags, because of a long cable run or an overloaded supply, weakens the hold. A reliable power supply with battery backup, correctly sized, is part of the installation. The supply should be placed where it can be serviced and where it is protected from tampering.
A door position sensor, usually a small switch in the frame, tells the system whether the door is closed. Some maglocks include a sensor that reports whether the magnet and the plate are in contact, called bond sensing. These features help detect problems, such as a door that is not fully closed or a plate that has come loose, and can raise an alert before a failure.
Wiring must be neat and secure. Exposed wires at the door can be tampered with. Protective housings and sleeves help. Wires for the exit button, the sensor and the alarm connection should be labeled and documented.
Finally, the installer should leave a record: how the door is wired, where the power supply is, how the releases work and how to test them. That record is valuable when something goes wrong years later.
Residual magnetism, wear and other quirks
Maglocks have a few quirks that owners should know about. Residual magnetism is one: after power is removed, a trace of magnetism can remain in the core, making the door feel as if it is slightly stuck for a moment. Good quality magnets and plates minimize this, and installers sometimes add a small spacer or a coating to reduce it. If a door seems to cling after release, report it, because it can slow an exit.
Wear is another. The magnet face and the armature plate must stay clean and flat. Dirt, paint, rust or damage can reduce the holding area. The surfaces should be cleaned occasionally with a suitable method, and not painted over. Salt air and humidity speed up corrosion in coastal Miami, so a maglock in a damp environment needs more attention.
A third quirk is the hum or buzz some maglocks produce when powered, particularly when supplied with alternating current or a poor quality supply. A properly specified direct current supply avoids this. A buzzing lock can also indicate a misaligned plate.
Heat can matter. Magnets draw power continuously, and a poorly ventilated installation or an overworked supply can run hot. Over time this affects reliability. Choose hardware rated for continuous duty and check the supply periodically.
Finally, remember what a maglock does not do. It does not make a weak door strong. A door with a flimsy frame, a glass panel that can be broken or a gap that allows hardware to be reached from outside remains vulnerable. Treat the lock as one part of a layered plan, with attention to the door, lighting, alarms and habits.
Questions to ask before a maglock goes in
Before approving a maglock installation, ask the installer a short series of questions and expect clear, specific answers. Is this door on an exit route? What release arrangements will be provided, and which are independent of the controller? Will the door release when the fire alarm sounds, and who is connecting that? How will it behave during a power outage? How long will the battery last? How will the releases be tested, and how often?
Ask who has confirmed that the arrangement satisfies the rules for your building. Often the answer involves the fire marshal, the building department or a fire alarm contractor. If your building is part of a larger property, the landlord or association may also have requirements. Do not assume the locksmith has settled this for you, and do not agree to bypass a safety feature to save time.
Ask about the door and frame. Is the frame strong enough? Is the door properly aligned? Does the installer recommend repairs first? Ask about the mounting style and what the finished door will look like.
Ask about power and wiring: where the supply is, how the wires run, how the system will be protected. Ask about documentation: will you receive a description of how the door works, where the releases are and how to test them?
Ask what you will need to do. A maglock door is not install and forget. It needs periodic testing of releases, cleaning of surfaces and checking of the battery. Make one person responsible, and keep a log.
If you are thinking about maglocks for your business, call and describe the doors, what they protect, and who uses them. A technician can explain whether a maglock is a sensible option or whether another arrangement, such as an electric strike described on the page about electric strike installation, suits better. Pricing is given by phone, with an on-site visit for complicated work, and a service call charge explained before dispatch.
Questions people ask
Is a magnetic lock legal on an exit door?
It can be, but only when the door provides the release arrangements required for your building, such as a sensor or button, a manual release and a connection to the fire alarm. The rules depend on the building type and local authority. Ask the fire marshal or building department, or a qualified professional, to confirm the arrangement before relying on it.
What happens to a maglock door when the power goes out?
A maglock holds only while it has power, so when power is lost and any battery backup runs down, the door unlocks. That protects people inside but leaves the door unsecured. A business should decide whether that is acceptable for each door, and consider different hardware where staying locked during an outage matters.
Do I need a connection to the fire alarm?
For maglocks on exit routes, a connection that releases the doors when the alarm sounds is commonly part of the required arrangement. Whether it applies to your door depends on local rules and the building's use. The fire alarm contractor and the authority having jurisdiction can confirm. The installer should not skip it to save time.
Why does my maglock feel sticky after it releases?
A small amount of residual magnetism can remain in the core, or the plate may be misaligned or dirty. It can slow an exit, so it should be fixed. A technician can check alignment, clean the surfaces and, if needed, adjust or replace the plate or magnet. Report it rather than living with it.
Can a maglock be used outdoors in Miami?
Only with care. Rain, humidity and salt air can corrode the magnet face and the plate and weaken the hold. An outdoor maglock should be a model suited to exposure, mounted and protected properly, and inspected regularly. For exposed doors, a technician may recommend a different type of lock altogether.
How are maglock jobs priced?
Prices are given by phone after you describe the door, the frame, the exit arrangements and the power situation. Complicated work, particularly on exit routes or fire alarm connections, needs an on-site visit first. A service call charge applies to dispatch and is explained on the phone before anyone is sent. No prices are published here.
Describe the situation by phone and we will tell you what the job involves. Quotes are given by phone. Jobs that cannot be quoted without seeing them need a technician on site, and the service call charge is explained on the phone before anyone is dispatched.
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Written by Claude (AI) (AI) for 24 Hour Locksmith Miami.