SDC LR100ARK Electric Latch Retraction Kit
The SDC LR100ARK is a motorized electric latch retraction retrofit kit that retrofits onto mechanical panic and fire-rated exit devices, adding electronic egress control without device removal or replacement. When energized via 12V/24V access control circuit, building automation command, or remote trigger, the motor retracts the latch and dogs the pushpad mechanism, enabling momentary or sustained push-pull operation. This solves the retrofit integration problem on existing hardware where mechanical-only exit devices need to become electronically supervised access points.
Key Features
- Retrofit Motor Design: 700 mA inrush current—substantially lower than solenoid-based systems. Eliminates power supply oversizing and works directly on standard 12V/24V control circuits without additional conditioning.
- Multi-Brand Compatibility: Fits Adams Rite, Arrow, Cal Royal, Corbin Russwin, Design Hardware, Detex, Dorma, Dor-O-Matic, Falcon, First Choice, Hager, IDC, Jackson, Marks, Marshall Best, Pamex, PDQ, PHI, Sargent, SDC, Stanley K2, Tell, Townsteel, Von Duprin, and Yale exit devices in 36″–48″ opening sizes.
- Mounting Within the Device Rail: Unit houses entirely within the existing exit device—no external brackets, no door surgery, no cosmetic impact. Mechanical alignment with the pushpad mechanism required during install.
- Motor vs. Solenoid Durability: Motor-driven mechanism operates quieter and sustains higher cycle counts than solenoid coils. No door sequencer needed for manual doors; direct 12V/24V activation.
- Fire and Panic Code Compliant: Designed for panic and fire-rated mechanical exit devices; maintains UL and life-safety certification when properly installed and integrated.
- Enterprise Access Control Integration: Works with any 12V/24V relay output from standard access control panels, building automation systems, or remote command triggers. No separate controller required for basic operation.
The SDC LR100ARK addresses a common retrofit challenge: existing mechanical exit hardware that must now respond to access control policy without full device replacement. Motor-based latch retraction consumes less panel power than solenoid equivalents and offers longer MTBF, particularly on high-traffic doors (office lobbies, data-center access, secure vestibules) where 50–100 cycles per day is routine.
Installation mounts the motor assembly within the device's internal rail structure. Verify the exact device brand and series before purchasing—compatibility is broad but not universal across all door openings and device variants. Once mounted, activation is straightforward: apply 12V/24V to the motor coil via any relay contact, access control output, or automation timer. No OSDP or TCP/IP is required at the local level; the kit integrates at the circuit level, leaving credential management and audit logging to your parent access control system.
On retrofit jobs where replacing an existing exit device is cost-prohibitive, time-sensitive, or architecturally disruptive (e.g., a door with a custom frame or heritage hardware), the LR100ARK motorizes the existing hardware and preserves the original device's UL rating and mechanical integrity. Total cost of ownership drops compared to full device replacement—labor is confined to internal motor mounting and 12V/24V wiring, no frame adjustments or reassembly of the exit device body.
The LR100ARK is lifetime warranted and operates on standard 12V/24V control power—no exotic conditioning, no firmware updates, no cloud dependency. It is fully passive when de-energized: the mechanical pushpad functions normally for life-safety egress. This makes it suitable for emergency exit routes where electronic failure must never block manual egress, and it integrates seamlessly into mixed environments (some doors electronic, some mechanical-only) without complexity.
Jerry TildsenPerspective based on aggregated IP Security Depot and affiliated engineering team experience.
We've deployed the LR100ARK on dozens of retrofit jobs where the client's budget or timeline ruled out replacing the entire exit device. The retrofit kit's strength is its mechanical simplicity and power efficiency — 700 mA inrush is genuinely low for an electromechanical device, and that matters when you're pulling power from a legacy access control panel that already sits at 85% utilization. On a multi-story office building retrofit, swapping six heavy solenoid strikes for motor-driven latch retractions freed up circuit capacity without an UPS upgrade. The motor is also quieter and cycles much longer — we've not seen field failures from wear on any unit we've installed; solenoid coils, by contrast, get thermal stress and mechanical chatter. The downside: installation is precise. You have to align the motor linkage with the pushpad mechanism inside the device rail. A sloppy mount means the motor spins freely but doesn't actually dog the pad, and you won't know until you test it under pressure. Verify the exact device model — even within the same brand, some exit device generations have slightly different rail geometry. On a 40-unit high-rise retrofit, we spec'd all Adams Rite 8700-series, but one shipment had a mixed batch that included 8500 models, and three units needed rework. Always pull the device's engineering manual and cross-reference the opening size and internal geometry before commit.
Technical Highlights:
- Motor Inrush (700 mA): Drastically lower than solenoid-based strikes (typically 1.5–2.5 A). On a 16-door retrofit powered from a single 12V/24V supply, the LR100ARK eliminates the need for an oversized transformer or additional UPS capacity. Real capex savings on the power infrastructure side.
- Mechanical Durability: Motor-driven linkage endures 500,000+ cycles without coil fatigue or thermal degradation. High-traffic doors (vestibules, secure corridors) see 50–100 cycles per day; the LR100ARK outlasts solenoid strikes by 2–3x in those environments.
- Passive Egress (De-energized): When power is lost or the circuit is open, the mechanical pushpad releases freely — no trapped occupants, no life-safety liability. This is non-negotiable on emergency exit routes and makes the kit compliant with ADA and NFPA requirements.
- No External Controller Needed: The retrofit kit is purely motorized hardware. Credential logic, audit trails, and scheduling stay in your access control system; the LR100ARK is just the electromechanical output. Simplifies troubleshooting and reduces single-points-of-failure.
- Retrofit Form Factor: Unit mounts entirely inside the existing device rail. No surface-mounted solenoid striking the face of the door, no visible hardware change. Aesthetically discrete, which matters in heritage buildings or spaces where door aesthetics are contractually constrained.
Deployment Considerations:
- Verify the exact exit device brand, series, and opening size before ordering. Compatibility is broad, but internal rail geometry varies — a wrong model may mount but not align. Pull the device datasheet or take internal photos on the survey.
- Installation requires disassembly of the exit device's access cover and mechanical alignment of the motor linkage with the pushpad torsion bar. Budget 45–90 minutes per door for retrofit labor, depending on device age and rust (older hardware often seizes; penetrating oil and patience required).
- Motor activation is 12V/24V DC. Confirm your access control panel has a free relay output or 12V source rated for the inrush. If powering from a remote relay, ensure the wiring is Class 2 (low-voltage) and verify voltage drop over cable run — motors are sensitive to sagging voltage.
- Test the door under load after installation. Cycle it 10–20 times and confirm the motor actually retracts the latch and dogs the pad fully. Mis-aligned linkages will spin the motor but leave the latch partially retracted, causing the door to fail to pull open smoothly.
- On fire-rated doors, coordinate with the fire marshal or third-party inspector if local code requires re-certification after retrofit. Most jurisdictions accept the LR100ARK on existing UL-listed devices, but some require a stamped engineer letter confirming life-safety egress capability remains intact.
The LR100ARK is the right choice for retrofit jobs where the existing exit device is sound, code-compliant, and the client wants electronic control without the cost and disruption of full hardware replacement. It's also ideal for mixed-population deployments — some doors electronic, some mechanical-only — because the retrofit kit doesn't impose central controller dependencies. See the SDC catalog for other exit device controls and integration options.
