Altronix RDC48 48VDC DIN Rail DPDT Relay Module
The Altronix RDC48 is a DIN rail-mounted relay module designed for 48VDC control circuits in security infrastructure. This UL-recognized component delivers DPDT (double-pole, double-throw) switching with a 10A maximum current capacity, enabling simultaneous control of two independent circuits — a critical feature in access control systems where failsafe and failopen operations demand redundant switching paths. Built for integration into standard security enclosures and control panels, the RDC48 eliminates the need for external relay banks and reduces wiring complexity in low-voltage DC signal routing applications.
Key Features
- DPDT Contact Configuration: Double-pole, double-throw allows independent control of two circuits or changeover switching of a single load. Enables simultaneous energizing of failsafe and failopen paths without additional relay modules.
- 10A Switching Current: Rated for up to 10A per pole — sufficient for lock solenoids, motorized strikes, and auxiliary control loads in access control systems without relay staging.
- 48VDC Input: Native 48VDC operation matches standard security system power distribution, eliminating voltage conversion losses and simplifying supply architecture.
- DIN Rail Mounting: Direct rail integration into standard 35mm DIN rail enclosures; no bracket adapters required. Compact footprint preserves panel real estate in retrofit installations.
- UL Recognition: Compliant with UL 508 Industrial Control Panel design standards, expediting panel certification for access control and alarm system applications.
- Lifetime Warranty: Manufacturer warranty covers defects in materials and workmanship for the operational life of the device.
The RDC48 is engineered for access control system integrators who need deterministic relay switching without the footprint or cost overhead of standalone electromagnetic relays. The DPDT configuration is particularly valuable in failsafe door control logic, where one pole energizes the electric strike during normal operation and the second pole de-energizes a failsafe solenoid lock upon power loss — both state changes managed by a single relay module. This reduces panel wire runs, eliminates cross-talk between control lines, and simplifies troubleshooting in complex multi-door installations.
Integration is straightforward across all major access control platforms. The RDC48 operates as a passive switching element — there is no firmware, no network communication, and no vendor lock-in. Wire the control signal to the coil terminals and route your load circuit through the appropriate pole-throw combination. This simplicity also means the relay can remain in service for decades without obsolescence concerns. In retrofit scenarios where legacy alarm panels are being upgraded with modern card readers, the RDC48 slots into existing enclosure DIN rails and reuses installed conduit runs.
Power consumption is negligible — the relay draws current only when the coil is energized. In always-energized duty cycles (e.g., holding a solenoid lock closed), calculate input power as coil voltage × coil resistance (typically 400–600 mΩ for 48VDC coils); expect 3–5W continuous draw. For intermittent switching applications (door access events, alarm relay actions), the RDC48's energy footprint is effectively invisible. Pair this with an uninterruptible 48VDC power supply, and you have failsafe switching that persists through AC mains loss — a fundamental requirement in security infrastructure.
Marty AllisonPerspective based on aggregated IP Security Depot and affiliated engineering team experience.
We've specified the RDC48 in hundreds of access control panel builds over the past decade, and it remains one of the most bulletproof components in the 48VDC switching ecosystem. The appeal isn't glamorous — it's reliability. DPDT relays in particular solve a real design problem: in failsafe systems, you often need two electrically independent paths, and trying to stack two single-pole relays introduces synchronization risk and panel clutter. The RDC48's integrated DPDT eliminates that headache. We've also seen integrators use it for motor control sequencing (e.g., unlocking a mortise and then unlatching a magnetic lock in timed sequence) because the two poles can be wired to fire at the same instant without relay contact chatter causing glitches. The UL recognition is quietly important too — if your panel is being certified by a third-party lab, having UL-recognized components in the bill of materials accelerates approval and reduces re-work. Compared to programmable logic alternatives (PICs, Arduino-based boards), the RDC48 trades flexibility for absolute determinism: no firmware bugs, no update cycles, no cyber-risk vectors. It's the right choice when you need a relay to do one thing reliably for 20 years.
Technical Highlights:
- DPDT Switching (dual independent circuits): One module replaces two single-pole relays in failsafe lock control. Synchronous pole switching prevents the brief window where both strike and failsafe solenoid could be de-energized, a critical safety property in emergency egress logic. Saves panel space, reduces wiring errors, and simplifies state testing.
- 10A per-pole capacity: Sufficient for most solenoid locks (typical draws 0.5–2A at 48VDC) and motor-driven strikes (up to ~5A). If your load exceeds 10A per circuit, you'll need a power relay or contactors upstream, but for standard access hardware, the RDC48 is the final switching stage.
- 48VDC native operation: No step-down transformer, no rectifier bridge, no efficiency loss. In large multi-door installations, this translates to lower overall power consumption and smaller UPS battery capacity. On a 32-door system running 24/7, that's real money saved over the lifecycle.
- DIN rail form factor: Eliminates custom mounting brackets. Drop it into any standard security enclosure, and you're done. Retrofit integrations where space is tight benefit especially from this density.
- Latching vs. momentary coil operation: The RDC48 uses a continuously energized coil (not latching) — the relay energizes when 48VDC is applied to the coil and de-energizes when power is removed. In failsafe designs, this means power loss triggers the failsafe condition instantly, with no moving parts to jam or contacts to stick.
Deployment Considerations:
- Coil voltage is always 48VDC — confirm your control signal source outputs clean 48VDC before wiring the relay coil. If your control board is 12VDC logic, you'll need an intermediate relay or solid-state switch to drive the RDC48 coil.
- Contact rating is 10A maximum across all operating conditions; if your solenoid lock draws 8A and you try to daisy-chain two devices on the same pole, you'll exceed the rating and cause premature contact wear. Single load per pole is the safe design pattern.
- Relay coils generate back-EMF when de-energized — if your control logic is solid-state (transistor, MOSFET), always add a freewheeling diode across the coil to suppress voltage spikes. Omitting this can destroy your control circuit. The RDC48 itself is robust, but your driver isn't.
- DIN rail enclosures should have adequate ventilation if the RDC48 is cycling frequently (e.g., every second during an alarm event); relay coils dissipate heat proportional to on-time. In continuous-duty failsafe mode (coil always energized), calculate thermal load as I²R and ensure the enclosure doesn't exceed 60°C ambient.
- In remote installations (parking garage readers, warehouse perimeter doors), run the 48VDC supply through a dedicated fused circuit to the RDC48; don't share power rails with noisy 12V camera supplies or PoE switches. Electrical noise can cause phantom relay chattering, creating false unlock events.
The RDC48 is the right choice for integrators building failsafe access control systems, or anyone retrofitting legacy relay logic without the budget or risk tolerance for a complete controls overhaul. Its simplicity and proven reliability in the field make it a no-brainer specification. Learn more about Altronix's complete line of control modules and power supplies in the Altronix catalog.
