Lifesafety Power RD250/250-16 RD250/250-16

We've deployed the RD250/250-16 into dozens of mid-tier access control and surveillance racks over the past five years, and it remains one of the most reliable core power architectures in the 12/24V space. The simultaneous dual-voltage output solves a real integration headache: most mixed-voltage installations we encounter need to power 24V magnetic locks alongside 12V legacy readers or 12V surveillance equipment, and the traditional approach — two separate supplies with external relay distribution — eats rack real estate and introduces redundant cabling. The RD250/250-16 eliminates that waste. The 16 hardwired egress relay outputs are the key differentiator; they're not auxiliary, they're structural. In a typical four-to-six door access control cabinet, those 16 contacts represent the entire distribution layer — you wire the door locks directly to the unit, not to an external relay board. This reduces labor during build-out and troubleshooting later. We've seen integrators who started with external relay panels switch to the RD250/250-16 and recoup the equipment cost in wiring labor savings alone on their next three installations.

Technical Highlights:

• Simultaneous 12V @ 20A and 24V @ 10A Output: Unlike sequential or parallel multi-voltage supplies, this unit delivers both rails at full rated amperage concurrently. For a typical installation with four 2A mag locks (8A @ 24V) and four 12V readers at 0.5A each (2A @ 12V), you have headroom and current reserve — critical when you add a door controller or future expansion. This prevents the cascade of voltage sag that kills access control reliability.
• 16 Normally Open Relay Contacts, 2A Per Contact: Each contact is rated for 2A resistive load — sufficient for a single solenoid strike or mag lock. If you're driving multiple locks from a single output, you'll need external relays, but the architecture assumes one lock per contact line, which is the best practice anyway. Suppression diodes on solenoid coils are non-negotiable; we've seen relay contacts weld without them on the first power-up cycle.
• 19-Inch Rackmount, ~6–8 Inches Depth: Fits standard horizontal mount in any commercial security rack. Depth varies by enclosure variant (some suppliers ship it slightly deeper), so measure your available space. It integrates neatly alongside a 2U NVR and a 1U access control panel, leaving room for a PoE switch or patch panel above.
• 120/240V AC Input Switchable: North American dual-voltage support. We've deployed this across mixed facilities where some buildings have 120V-only circuits and others have 240V; the switch eliminates SKU complexity and inventory bloat.
• Single Common Ground Bus: Both 12V and 24V rails share the same ground reference. This is critical — floating grounds between the two rails create noise coupling that manifests as intermittent lock releases or false alarms. We always verify continuity between the 12V and 24V grounds during final testing before handing off.

Deployment Considerations:

• Current Budget at 24V Rail Is Tight: The 10A limit on 24V output seems generous until you add a door controller (0.5A), a mag lock (2A), a strike (1.5A), and readers (0.5A each). Four-door cabinet can approach or exceed 10A — you need a load audit before installation. We've seen integrators discover over-subscription only when they tried to de-energize a secondary lock during alarm conditions.
• Long Cable Runs Drop Voltage: A 50-foot run from the rack to a remote door can lose 2–3V on the 24V rail if you're not using adequate gauge wire (10AWG minimum recommended for 20+ foot runs). Test lock release time under full load and real cabling before final sign-off. A mag lock that releases at 20V may not release reliably at 17–18V due to voltage drop.
• Solenoid Suppression Diodes Are Not Optional: Every inductive load (electric strike, RTE solenoid) needs a 1N4007 or similar suppression diode across the coil. Without it, relay contact arcing and welding will fail the outputs within weeks. We spec suppression in every door control wiring diagram and verify installation during commissioning.
• Ground Bus Discipline: Wire both 12V and 24V commons to the same ground reference point in the rack — typically the main ground bar on the access control panel or UPS. Floating grounds between the two rails will cause intermittent lock behavior that's maddening to diagnose after installation. Make this a checklist item during final inspection.
• AC Input Breaker Sizing: Size the incoming AC breaker to the total load, not a generic 15A. A fully loaded RD250/250-16 drawing 250W on the DC side will require roughly 20A at 120V input (assuming 85% efficiency). We've seen under-breaker problems cause nuisance trips on installations with multiple locks and readers operating simultaneously.

The RD250/250-16 is the right choice for integrators building mid-tier access control and surveillance racks where you need simultaneous 12V and 24V power on a single backbone. It's not appropriate for single-voltage installations (you'd over-specify), and it's not powerful enough for enterprise multi-building campuses (you'd need multiple units or a larger platform). For the sweet spot — four-to-eight doors on a single access control panel with mixed 12V and 24V hardware — this supply eliminates wiring complexity, reduces labor, and provides reliable 24/7 operation. See the Lifesafety Power catalog for alternative form factors and higher-capacity models.