What This Article Covers and Who It Helps
Bundled magnetic lock kits that include a weatherproof keypad and an integrated power supply look straightforward on a spec sheet. Contractors installing them on exterior commercial doors, facility managers retrofitting secondary entry points at schools or industrial buildings, and architects writing access control hardware schedules all run into the same problem: the power supply and wiring decisions are treated as afterthoughts, finalized after the lock body is already mounted and the opening is partly closed in. This guide explains why that sequence creates field problems, and what to nail down before the hardware ships.
What a Magnetic Lock Kit Actually Includes
An electromagnetic lock kit for an exterior entry typically bundles three core components:
- The electromagnetic lock body — mounts in the frame header; holds the door closed by magnetic force when energized
- An armature plate — surface-mounted on the door face, mates with the lock body
- A weatherproof keypad — provides credential input on the unsecured (exterior) side
- A power supply — converts facility AC power to regulated DC for the lock and keypad
- A request-to-exit (REX) device or push button — mounted on the interior egress side
When all five pieces arrive as a kit, there is a temptation to assume they are pre-matched and ready to wire. They often are not sized for every site condition, and the power supply is where the mismatch most commonly surfaces.
Why the Power Supply Gets Chosen Wrong on Exterior Openings
Interior applications of electromagnetic locks are relatively forgiving. Exterior doors introduce variables that change the electrical load and the enclosure requirements significantly.
Voltage Drop Over Long Wire Runs
On exterior doors at loading docks, perimeter gates, portable classrooms, or outbuildings, the power supply is rarely within a few feet of the lock. Wire runs of 50 feet or more are common. Voltage drop over that distance can reduce the effective voltage at the lock body below the threshold the manufacturer requires to maintain rated holding force. A 1,200-pound-rated electromagnetic lock operating at reduced voltage will hold at a fraction of that force under a sustained pull test. If the power supply and wire gauge were not selected together based on the actual run length, the lock underperforms from day one without any visible sign of the problem.
Current Draw When the Keypad Is Added to the Circuit
A weatherproof keypad draws its own current, and bundled kits do not always size the included power supply to carry both the lock body and the keypad on the same output simultaneously. When a credential is presented and the keypad backlights or activates a relay, the combined draw can momentarily exceed the supply rating. Some installers only discover this during commissioning when the lock drops out at the moment the keypad is triggered.
Enclosure Rating vs. Actual Exposure
Power supplies in bundled kits are often rated for interior use or for a protected interior enclosure. On exterior applications at schools, healthcare campuses, and industrial facilities, the power supply needs to be housed in an appropriately rated enclosure or located in a climate-controlled interior space. Placing an interior-rated supply in an exterior soffit or unheated mechanical space shortens service life and can cause erratic lock behavior in cold weather.
The Egress Compliance Check That Cannot Wait
Electromagnetic locks on egress-side doors carry specific code requirements under both the International Building Code and NFPA 101. The core rules that govern these openings include:
- The lock must release upon loss of power to the lock itself
- The lock must release upon activation of the fire alarm system
- A listed sensor or a push button marked Push to Exit must be provided on the egress side, located between 40 and 48 inches above the floor and within 5 feet of the door, releasing the lock for a minimum of 30 seconds
- The release must be independent of the access control system
On exterior magnetic lock kits, the REX push button or motion sensor is sometimes treated as an optional accessory rather than a required component. In occupancies open to the public, including retail, schools, and healthcare facilities, the door cannot be secured from the egress side when the building is occupied. The power supply must be wired so that a fire alarm panel dry contact can interrupt lock power directly. That fire alarm interface has to be scoped before the power supply is ordered, not after the lock is on the door.
What to Confirm Before the Kit Ships
The following decisions need to be made at the point of specification or purchase, not during installation:
- Actual wire run length from the power supply location to the lock body, accounting for conduit routing rather than straight-line distance
- Wire gauge selection based on that measured run and the combined current draw of the lock and keypad
- Power supply capacity — confirm the included supply handles the total load at the end of the wire run with appropriate headroom
- Power supply enclosure location — interior, climate-controlled, and accessible for future service
- Fire alarm interface method — confirm the power supply has a dry-contact input or that an appropriate relay is added to the order
- REX device type — motion sensor, push button, or both; confirm mounting location meets code height requirements
- Fail-safe behavior — electromagnetic locks are inherently fail-safe (power off equals door open); confirm this is acceptable for the opening's security profile and confirm with the AHJ if required
Applications Where This Sequence Problem Is Most Common
The power supply selection mistake shows up consistently across several project types:
- K-12 schools adding controlled entry to exterior campus doors as part of a security upgrade, where the power supply is often specified by the low-voltage contractor after the architectural hardware is already ordered
- Healthcare campuses securing secondary exterior entries to restricted areas, where fire alarm integration is mandatory and is sometimes scoped by a separate trade
- Industrial and warehouse facilities controlling perimeter doors where wire runs to a central power panel are long and conduit routing adds significant length
- Retail and multi-tenant commercial properties retrofitting after-hours controlled access on exterior doors that were originally hardware-only openings
A Note on Bundled Kits vs. Component Specification
Bundled magnetic lock kits offer real convenience for straightforward interior or short-run applications. For exterior openings with long wire runs, fire alarm integration requirements, or exposure concerns, building out the system from individual components selected for the specific conditions often produces a more reliable and code-compliant installation. DoorwaysPlus carries electromagnetic locks, weatherproof keypads, power supplies, REX devices, and mounting accessories as both bundled kits and individual components, so the right configuration for the opening can be put together before anything ships.
If you are specifying or ordering a magnetic lock kit for an exterior opening, contact the DoorwaysPlus team before finalizing the order. A five-minute conversation about wire run length and fire alarm interface can prevent a costly revisit after the door is already in service.