What This Article Covers and Who It Helps
Electric strikes do more than release a latch when a credential is presented. On monitored openings, the strike itself reports back to the access control system: is the door actually latched? Is the locking cam engaged? Contractors wiring access control systems, security integrators commissioning panels, and facility managers troubleshooting nuisance alarms all run into the same gap -- the auxiliary switch and its monitoring circuits are wired after the fact, or not at all, and the opening never performs as the spec intended.
This article explains what latchbolt monitoring and locking cam monitoring mean in practice, how the auxiliary switch fits into a complete access control workflow, and what gets missed at rough-in that causes problems at commissioning.
What Is an Auxiliary Switch on an Electric Strike?
An electric strike replaces the flat strike plate in a door frame. When power is applied (or removed, depending on fail-safe or fail-secure configuration), the strike keeper pivots to release the latch and allow the door to open. That is the primary function.
The auxiliary switch is a secondary output built into the strike body -- typically a single-pole double-throw (SPDT) dry contact. It changes state in response to a mechanical event inside the strike: the latch entering the keeper pocket, the cam rotating to the locked position, or both. That signal travels back to the access control panel, alarm panel, or building management system to report door status in real time.
On a strike with latchbolt monitoring, the switch confirms whether the latch bolt has physically entered the strike pocket -- meaning the door is closed and latched. On a strike with locking cam monitoring, the switch confirms the internal cam has rotated to its secured position. When both are combined, the panel has a more complete picture: the door is closed, latched, and the strike mechanism is in the correct state.
Why Monitoring Matters Beyond the Card Reader
A common assumption is that door position switches handle all status reporting. A magnetic contact on the door frame tells the panel whether the door is open or closed. That is useful, but it does not tell the system whether the door is latched. A door can be physically closed against the frame, registering as closed at the door position switch, while the latch bolt never entered the keeper -- either because the door was pulled shut without fully engaging, the latch is misaligned, or the hardware has worn over time.
In applications where positive latching is required -- fire-rated openings, secure rooms, pharmacy storage in healthcare facilities, server rooms, or access-controlled stairwells -- that distinction matters. The auxiliary switch on a monitoring-capable strike closes the reporting gap between "door is closed" and "door is secured."
Applications Where Strike Monitoring Is Most Valuable
- Healthcare: Pharmacy and controlled substance rooms require verified secure status, not just door closure. Monitoring-capable strikes support audit trails that satisfy regulatory inspection.
- Schools and universities: Classroom lockdown protocols depend on confirmed latching after a lock command. A strike with cam monitoring confirms the locking cycle completed, not just that power was applied.
- Retail and commercial: After-hours lock verification for multi-site facilities; remote monitoring dashboards require accurate latch status per door.
- Industrial: Server rooms, chemical storage, and equipment access points where an unsecured door triggers an immediate alert rather than a discovered problem during rounds.
- Stairwells and re-entry doors: Where NFPA 101 stairwell re-entry requirements interact with access control, monitoring confirms re-entry locking is functioning correctly after each use cycle.
Fail-Secure vs. Fail-Safe and What Monitoring Changes
The monitoring function is independent of the strike's fail state, but the two must be understood together when wiring the opening.
In a fail-secure configuration, the strike is locked by default and releases when power is applied. Loss of power returns the strike to the locked, latched state. This configuration is fire-listable and is preferred by code officials because egress remains available through the mechanical latch hardware -- the occupant uses the lever or panic bar to retract the latch regardless of strike state.
In a fail-safe configuration, the strike releases on power loss. This is appropriate for certain occupancies where egress must be guaranteed on power failure, but it cannot be used on fire-labeled openings because the door will not positively latch when power is removed.
The auxiliary switch output behaves differently in each configuration. When commissioning, verify the monitoring logic at the panel matches the strike's fail state -- a fail-safe strike that reports "secured" when power is off is reporting the opposite condition from a fail-secure strike in the same switch state. Mismatched logic produces false alarms or, worse, missed alarms.
What Gets Missed at Rough-In
The most common field problem with monitored electric strikes is not the strike itself -- it is the wiring plan. Strike monitoring requires additional conductors back to the panel beyond the two wires for strike power. A typical monitoring-capable strike needs:
- Two conductors for strike power (and return)
- Two to three additional conductors for the auxiliary switch output (common, normally open, normally closed)
- Correct voltage and current capacity at the strike -- 24V DC is the most common specification for commercial access control applications
When the rough-in conduit is pulled for two conductors and the spec calls for a monitoring-capable strike, the integrator arrives at commissioning to find they cannot terminate the switch. Retrofitting conductors through finished walls in a healthcare corridor or a completed school renovation is expensive and disruptive. The solution is to read the full strike specification before conduit is pulled and run the correct conductor count from the start.
Finish and Environment Considerations
Electric strikes installed in frame faces are exposed to cleaning chemicals in healthcare settings, humidity in exterior vestibules, and heavy use in school corridors. Specifying the correct finish for the environment is not cosmetic -- it affects the longevity of the internal mechanism. Satin stainless finishes (US32D / 630) perform well in high-moisture and high-cleaning-frequency environments and are a common default on institutional projects.
How to Spec a Monitoring-Capable Electric Strike Correctly
When writing the hardware set for a monitored opening, confirm the following before the order is placed:
- Strike type: Mortise, cylindrical, or surface-mounted (rim) -- must match the lock body on the door
- Monitoring features needed: Latchbolt only, cam only, or both -- confirm with the access control panel manufacturer what signals the panel can read
- Fail state: Fail-secure (fire-listable) or fail-safe (non-rated openings only)
- Voltage: 12V or 24V DC -- match to the power supply and panel output
- Conductor count: Coordinate with the low-voltage contractor before conduit is stubbed at the frame
- Finish: Match to the opening environment and hardware set finish schedule
- Fire listing: If the opening is fire-rated, confirm the strike model carries a fire listing in fail-secure configuration
DoorwaysPlus carries monitoring-capable electric strikes from preferred lines including products suited for mortise and cylindrical lock applications, in 12V and 24V configurations, with auxiliary switch outputs for integration into access control and building management systems. If your project requires a specific combination of monitoring features and fire listing, the team can help confirm compatibility before you commit to the rough-in.
The Takeaway for Contractors and Specifiers
An electric strike with an auxiliary switch is not just a release device -- it is a reporting device. Latchbolt and cam monitoring close the gap between what the access control panel assumes and what the door is actually doing. Getting that monitoring signal to the panel requires the right strike model, the right conductor count at rough-in, and a wiring logic that matches the strike's fail state. Coordinate those three things before the frame is set and you avoid the most common commissioning delays on monitored openings.