Camden CM-2250 Key Switch SPDT Momentary
The Camden CM-2250 is a key switch control module designed for 30VDC access control applications requiring manual key-based activation of door strikes, electromagnetic locks, and auxiliary equipment. The SPDT (single-pole, double-throw) momentary relay configuration delivers a brief pulse output — eliminating sustained relay chatter and enabling single-action gate or strike activation without continuous solenoid energization. Deploy this in facilities where authorized personnel need physical key-based override independent of card readers or biometric systems, or in dual-authorization scenarios where both key and badge must complete an unlock sequence.
Key Features
- SPDT Momentary Relay: Single pulse output on key turn — prevents lock chatter and reduces solenoid heating. Ideal for one-time activation sequences in high-frequency environments.
- 30VDC Rated Supply: Operates on standard low-voltage access control power. Compatible with most access control panels and strike controllers. Confirm strike voltage matches 30VDC to prevent relay damage.
- Mortise Cylinder Cavity: Accepts standard 1", 1 1/8", or 1 1/4" mortise cylinders. Sourced separately — allows site-specific keying and rekeying without module replacement.
- Flush-Mount Single-Gang Form Factor: 2 3/4" width fits standard single-gang openings in door frames and narrow mounting locations. Compact design reduces installation footprint on congested door hardware.
- Cast Tamper/Vandal Resistant Assembly: One-piece construction withstands high-frequency industrial use, outdoor weather exposure, and deliberate tampering attempts. No exposed wiring or fasteners.
- Dual Strike/Auxiliary Output: SPDT configuration allows simultaneous or alternative control of two devices (e.g., primary strike + auxiliary gate operator, or strike + alarm silencer).
The CM-2250 integrates into any access control system managing door strikes, overhead operators, or electromagnetic locks via 30VDC momentary relay input. The module requires no power supply of its own — it draws control current from the access panel or strike controller's 30VDC bus. Wiring is simple: connect the 30VDC supply and two strike/auxiliary load lines to the relay terminals. The assembly ships with mounting screws, tamperproof hardware, and a brass cylinder lock ring; the mortise cylinder is ordered separately from Camden or a compatible cylinder vendor.
The momentary relay design is operationally superior to maintained or latching outputs in high-duty cycles. In a busy commercial entry with 500+ daily badge swipes, a maintained relay forces continuous solenoid energization on every unlock command — generating heat, accelerating coil failure, and consuming unnecessary power. The CM-2250's pulse output energizes the strike only for the brief moment of key turn, then de-energizes automatically. This reduces electromagnetic wear and allows the strike to reset naturally without manual intervention.
Deployment scenarios include secondary override stations where a manager needs manual key access to a door without the building access control system (e.g., after-hours emergency egress, facilities lockdown), dual-factor unlock (card + key) for high-security areas, and maintenance/engineering workstations where key control is simpler than badge provisioning. The flush mount also suits retrofit installations in narrow frame widths where cabinet-mounted relays would obstruct doorways.
The Camden CM-2250 carries manufacturer warranty coverage and is sourced direct from Camden Door Controls. Integrators should confirm strike voltage and load current ratings before installation — 30VDC is the sole supported supply voltage. Over-voltage conditions will destroy the relay contacts. For facilities requiring wider-format mounting or alternative relay configurations, review the CM-2200 (1 3/4" width, narrower frame fit) and Camden's full line of key switch and relay modules.
Eden PhillipsPerspective based on aggregated IP Security Depot and affiliated engineering team experience.
We've deployed the Camden CM-2250 across dozens of commercial and light-industrial sites as a reliable failsafe for key-based door override. The real operational win is the momentary relay architecture — it removes the complexity of maintained versus latching relay logic and eliminates the control-panel programming headaches that come with dual-state relays. On a busy building with manual override stations, the SPDT momentary design means the key turn initiates a pulse, the strike energizes for 400–600ms, and then de-energizes on its own. No solenoid holding current, no burned-out coils at 2 a.m., no late-night calls because a technician left a relay energized. The 30VDC supply voltage is standard in access control environments, so integration is straightforward — it plugs into any access panel or strike controller 30VDC auxiliary output without additional power conditioning.
The mortise cylinder cavity design is deliberately flexible. Rather than ship a pre-keyed cylinder, Camden leaves that blank so you can order the exact cylinder type and key system that matches your site's master key hierarchy. We've seen integrators get hung up trying to rekey pre-installed cylinders; this module avoids that friction entirely. The flush-mount 2 3/4" width is the standard, but if your door frame is narrower (older buildings, re-strikes), the CM-2200 at 1 3/4" is a drop-in alternative.
Technical Highlights:
- SPDT Momentary Relay Output: Delivers a timed pulse on key turn — typically 400–600ms — without sustained coil energization. Reduces heat dissipation in the strike solenoid and extends electromagnetic lock service life by 30–40% versus maintained relay designs. Critical in high-frequency access points.
- 30VDC Supply Rating: The sole supported voltage. Operates on the common 30VDC bus in access control cabinets and strike controllers. Do not over-voltage; even 35VDC will arc the relay contacts. Confirm your strike controller output voltage before installation.
- Mortise Cylinder Cavity (1", 1 1/8", 1 1/4" compatible): Accepts standard US mortise cylinders. You source the cylinder separately, allowing alignment with your master key system. Rekeying is as simple as pulling and replacing the cylinder; the module itself never needs reprogramming.
- Flush-Mount Cast Assembly: Single-piece aluminum or zamak housing resists tampering, outdoor weather, and vibration from door slam cycles. No exposed relay contacts, no external wiring vulnerable to cutting or disconnection.
- Dual-Output SPDT Contact Set: One momentary pulse can independently energize two loads (primary strike + secondary gate operator, for example), or toggle between two load states. Simplifies system logic where a single key-turn must coordinate multiple electromechanical devices.
Deployment Considerations:
- Voltage matching is non-negotiable. The CM-2250 is rated 30VDC only. Verify your strike controller and access panel both supply 30VDC before wiring. A 24VDC system will under-energize the relay; a 48VDC system will destroy it in seconds.
- Mortise cylinder sourcing adds lead time. The CM-2250 ships without a cylinder — you must order separately. Common options include US mortise cylinders keyed to your master system or a blank cylinder for on-site rekeying. Budget 1–2 weeks for cylinder delivery if not stocking spares.
- Momentary pulse duration is fixed (typically 400–600ms). If your strike solenoid requires longer energization or if you need a maintained lock state, the CM-2250 is not the right choice — consider a latching relay module instead. Test pulse timing with your specific strike controller in the lab before field deployment.
- Flush mounting requires a clean single-gang opening (2 3/4" width). Older door frames or re-strike installations may need frame reinforcement or the narrower CM-2200 variant. Measure the available opening depth and width before ordering to avoid field modifications.
- The key switch is a single mechanical element — no audit trail, no credential logging. Use this for fallback override or after-hours access, not for primary entry control or occupancy tracking. Pair with a badge reader and panel log if you need accountability.
The CM-2250 is the right choice for integrators specifying failsafe key override in access control systems, emergency egress stations, and dual-factor unlock scenarios where simplicity and reliability outweigh the need for detailed logging. It's especially valuable in industrial and light-manufacturing environments where mechanical switches are preferred over electronic badge readers due to dust, moisture, or harsh conditions. Review the Camden catalog for complementary strike controllers, power supplies, and alternative key switch configurations.
