SDC 25-4U Electric Strike, Reversible Failsafe/Failsecure, 12/24V AC/DC

The SDC 25-4U is a heavy-duty, low-profile electric door strike designed for electronic access control applications using cylindrical locksets and hollow metal or aluminum door frames. Part of the Security Door Controls (SDC) 25 Series, this centerline latch-entry strike accommodates 1/2-inch latchbolts or latchbolts up to 9/16 inch with a 1/8-inch door gap. It features field-selectable 12/24 VDC operation, configurable fail-secure or fail-safe functionality, and an integrated SPDT latch status monitoring switch rated at 3 amps at 30 VDC. The strike includes a 4-7/8-inch square-corner stainless steel faceplate in a 630 dull stainless finish, corrosion-resistant components, an internally mounted solenoid, and mounting tabs for installation in limited jamb spaces. With a 1,000-pound static strength rating and 250,000-cycle endurance specification, the SDC 25-4U provides electrically controlled door release for commercial offices, institutional buildings, and other high-traffic security applications.

SDC 25-4U 25 Series Electric Strike with Latch Status, 630 Stainless Steel

The SDC 25-4U Electric Strike provides electrically controlled door release for commercial access control systems requiring compatibility with conventional cylindrical locking hardware. Manufactured by Security Door Controls as part of the 25 Series, this compact electric strike incorporates a centerline latch-entry design, field-selectable fail-secure or fail-safe operation, and integrated latch status monitoring. The strike is designed for hollow metal and aluminum door frames and accepts standard 1/2-inch latchbolts or latchbolts up to 9/16 inch when an appropriate 1/8-inch door gap is maintained. Its low-profile construction and internally mounted solenoid minimize the space required inside the door jamb, making the unit suitable for both new construction and retrofit installations. The 4-7/8-inch square-corner faceplate with a 630 dull stainless steel finish provides a durable appearance that coordinates with commercial architectural hardware. Typical applications include office entrances, controlled interior doors, warehouses, educational facilities, and institutional buildings requiring electronic access control.

The SDC 25-4U incorporates stainless steel operating components, a corrosion-resistant die-cast housing, and an internally mounted electromagnetic solenoid engineered for dependable operation in high-traffic installations. The manufacturer specifies a 1,000-pound static strength rating, 50-pound dynamic strength rating, and 250,000-cycle endurance rating. Its square-corner faceplate measures 4-7/8 inches high by 1-1/4 inches wide, while the compact strike assembly supports installation in restricted frame cavities. The operator accepts a 12 or 24 VDC power supply with field-selectable voltage configuration, allowing integration with compatible access control power supplies and relay-controlled release circuits. Electrical current requirements are approximately 200 mA at 12 VDC, with the applicable 24 VDC current rating dependent on the manufacturer's documentation revision. The strike also incorporates voltage and current spike protection and includes a single-pole, double-throw (SPDT) latch status switch rated at 3 amps at 30 VDC resistive. The 25 Series is identified by the manufacturer as meeting UL 1034 burglary-resistant electric locking mechanism requirements and ANSI/BHMA A156.31 electric strike standards.

For electronic access control applications, the SDC 25-4U provides configurable fail-secure and fail-safe operation to accommodate different security and door release requirements. In fail-secure configuration, the electric strike remains mechanically secured when electrical power is removed and releases the latch when appropriately energized. In fail-safe configuration, the strike releases upon loss of power, subject to the installation and applicable life-safety requirements. The operating mode can be changed in the field by repositioning the manufacturer's designated configuration screw, eliminating the need to purchase separate models for each operating mode. The integrated latch status monitoring switch provides normally open, normally closed, and common contacts, allowing compatible access controllers, security alarm panels, and building monitoring systems to receive information about latch engagement. This monitoring capability supports door security supervision and access control event processing when integrated with appropriate control equipment. The strike can operate with compatible card readers, keypads, request-to-exit devices, and electronic access control systems through an external control relay and regulated DC power supply.

Installation of the SDC 25-4U surface-frame electric strike requires accurate alignment between the cylindrical lockset latchbolt and the strike's centerline entry opening. The manufacturer specifies that the latch must enter the strike at the centerline positioned precisely between the upper and lower ends of the faceplate. The non-handed, field-reversible design accommodates left-hand and right-hand door configurations, while the included retrofit mounting tabs facilitate installation in hollow metal frames without existing strike mounting provisions. Wiring connections support either 12 VDC or 24 VDC operation, with separate conductors provided for the integrated latch status output. Installers can configure the desired fail-secure or fail-safe operating mode before final assembly and verify proper latch engagement and electrical release after installation. An optional RMB audible buzzer is available in the related 25-4URMB configuration, while the SDC BR64XL bridge rectifier provides an accessory option for compatible AC-powered installations. Backed by a five-year manufacturer warranty, the SDC 25-4U combines compact construction, selectable operating functions, integrated latch monitoring, and durable stainless steel components for commercial electronic door release applications.