Technical Foundation
What Is a Automatic and Magnetic Door Holder?
An automatic magnetic door holder uses an electromagnet to hold a door open against a strike plate or armature mounted on the door itself, releasing instantly when power is cut — typically triggered by the building's fire alarm system so that fire-rated corridor and stairwell doors close automatically during an alarm event without relying on someone to close them manually. Wall-mounted units sit on the wall at the door's open position; floor-mounted units sit in the floor path, chosen based on wall clearance and traffic patterns.
Holding force is rated in pounds and must be adequate for the door's weight and any closing spring force it must overcome, but code (typically NFPA 80 and local fire code) requires the holder release on loss of power or signal from the fire alarm control panel — never require manual intervention to release. Units intended for life-safety fire door release must carry UL listing for that specific application, distinct from general-purpose magnetic door holders sold for everyday convenience use only.
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| Spec | What It Means | Why It Matters |
|---|---|---|
| Holding Force | Typically 25-100+ lb rated force | Must exceed the door's weight and closing mechanism resistance to hold reliably |
| Mounting Type | Wall mount, floor mount, surface mount | Selected based on available wall clearance, door swing and floor traffic path |
| Voltage | 12VDC or 24VDC common | Must match the fire alarm system's auxiliary power output or a dedicated power supply |
| Fire Alarm Integration | Direct tie-in vs. standalone holder | Fire-rated doors require the holder to release automatically on alarm signal per code |
| UL Listing | UL 228 listed for fire door releasing devices | Required for life-safety fire door applications, not just general convenience holding |
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Applications
Where Automatic and Magnetic Door Holders Get Used
Magnetic door holders are specified anywhere a door needs to be held open for daily traffic but must close automatically and reliably during a fire event.
Commercial Fire Door Systems
Automatic release of corridor and stairwell fire doors on fire alarm activation to maintain compartmentalization during an emergency.
Hospitals & Healthcare Facilities
Hold-open devices on frequently used doors with mandatory fire-alarm tie-in per life-safety code requirements.
Schools & Educational Buildings
Magnetic door holders on classroom and corridor doors that release automatically during fire drills and actual alarms.
Office Buildings & High-Rises
Stairwell and corridor door holders integrated with building fire alarm and access control systems.
Hotels & Multi-Family Housing
Door holders on common-area fire doors that must close automatically to contain smoke and fire spread between units.
Retail & Warehouse Facilities
General convenience magnetic door holders on non-fire-rated doors for everyday traffic flow, without alarm integration.
FAQ
Automatic and Magnetic Door Holders Questions, Answered
Do magnetic door holders on fire doors need to be tied into the fire alarm system?
Yes, for any fire-rated door — code requires the holder release the door automatically upon fire alarm activation, not just on a smoke detector at the door itself, so the unit must be UL 228 listed and wired into the building's fire alarm control panel, not sold as a standalone convenience holder.
What's the difference between a wall mount and floor mount door holder?
Wall mount holders attach to the wall surface at the door's open position and are used where wall space is available and clear of the door swing. Floor mount holders sit in the floor at the door's open position and are chosen when wall-mounting isn't practical — for example, glass walls, insufficient wall depth, or doors that open into open floor space.
How much holding force do I need for my door?
Holding force needs to comfortably exceed the door's own weight plus any closing spring or closer resistance working against it — heavier commercial doors with strong door closers typically need 40-100+ lb rated holders, while lighter doors may only need 25-45 lb units. When in doubt, oversizing holding force is safer than undersizing.
Can a magnetic door holder be used on a non-fire-rated door without alarm tie-in?
Yes — magnetic door holders intended purely for everyday convenience (holding doors open in offices, retail, etc.) don't require fire alarm integration or UL 228 listing, but any door that carries a fire rating must use a listed, alarm-integrated unit regardless of how it's used day-to-day.
What happens to the door holder when the fire alarm activates?
Power to the electromagnet is cut (either directly or via a signal to a compatible power supply), the magnetic field collapses instantly, and the door — driven by its own closer — swings shut. This is a fail-safe design: the holder always releases on loss of power, so an electrical fault also causes the door to close rather than stay open.
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