System Sensor 4W-B Photoelectric i3 Smoke Detector, 4-Wire

The System Sensor 4W-B is a 4-wire i3 Series photoelectric smoke detector with 2.5%/ft nominal smoke sensitivity, automatic drift compensation, and a 0.5A alarm contact rated at 30 VAC/DC for compatible conventional fire alarm and security systems. Operating on nominal 12/24 VDC, it features dual-color status LEDs, microprocessor-controlled smoke detection, and a removable sensing chamber for maintenance. The detector draws 50 A in standby, 20 mA during alarm at 12 VDC, or 23 mA at 24 VDC. Its included Stop-Drop 'N Lock mounting base supports prewiring and installation on standard electrical boxes.

System Sensor 4W-B i3 Series 4-Wire Photoelectric Smoke Detector

The System Sensor 4W-B is a conventional four-wire photoelectric smoke detector designed for integration with compatible fire alarm and intrusion security control panels. Part of the System Sensor i3 Series, the 4W-B uses an advanced optical sensing chamber and microprocessor-controlled detection technology to identify airborne smoke particles associated with developing fire conditions. The detector provides 2.5% obscuration per foot nominal smoke sensitivity and connects to a conventional alarm system using separate power and alarm circuit connections. Its four-wire design allows the detector to receive operating power independently while communicating alarm conditions through a dedicated dry-contact output. Designed for indoor fire protection applications, the 4W-B is suitable for residential properties, offices, retail establishments, institutional buildings, and other protected spaces requiring conventional smoke detection. Unlike combination smoke and heat models, the 4W-B provides photoelectric smoke detection only and does not include a fixed-temperature heat sensor or built-in audible sounder.

The System Sensor 4W-B operates on nominal 12 or 24 VDC power, with a manufacturer-specified operating range of 8.5-35 VDC. Its low-current sensing circuitry draws approximately 50 microamps during normal standby operation, 20 mA during alarm at 12 VDC, and 23 mA during alarm at 24 VDC. The detector incorporates normally open alarm contacts rated at 0.5 amps at 30 VAC/DC for signaling compatible conventional initiating device circuits. Advanced microprocessor-controlled drift compensation and smoothing algorithms automatically adjust smoke sensitivity as contaminants gradually accumulate in the optical chamber, helping maintain consistent detection performance and reduce nuisance alarms. The detector includes wide-angle green and red LED indicators that communicate power-up, normal operation, out-of-sensitivity, and alarm conditions. During normal standby, the green LED flashes approximately every five seconds, while a solid red LED indicates an active smoke alarm. A flashing red indication identifies an out-of-sensitivity condition requiring inspection or maintenance. The detector's latching alarm condition is reset by temporarily interrupting its operating power through compatible control panel circuitry.

The 4W-B incorporates a Stop-Drop 'N Lock plug-in mounting system that allows installers to complete electrical wiring at the base before attaching the detector head. The included mounting base supports installation on single-gang electrical boxes, 3-1/2-inch and 4-inch octagonal boxes, and 4-inch square boxes with plaster rings, as well as approved direct ceiling mounting. Its SEMS screw terminals accommodate 14-22 AWG conductors, providing secure connections for the separate power and alarm circuits. The detector measures 5.3 inches in diameter and 2 inches high, including the mounting base, and weighs approximately 6.3 ounces (178 grams). A built-in recessed test switch supports functional testing of the alarm circuitry, while compatible smoke entry testing verifies the response of the photoelectric sensing chamber. The detector also supports sensitivity measurement using the separately available System Sensor SENS-RDR infrared sensitivity reader, allowing technicians to evaluate detector sensitivity without removing it from its installed location. Its removable detector cover and optical sensing chamber simplify cleaning and maintenance, while the optional A77-AB2 retrofit adapter bracket supports replacement installations requiring a larger mounting footprint.

The System Sensor 4W-B is designed for indoor conventional fire detection applications requiring reliable photoelectric smoke sensing, low current consumption, and straightforward installation. It operates in ambient temperatures from 32 F to 120 F (0 C to 49 C) and supports relative humidity from 0% to 95%, noncondensing. The detector is UL 268 Listed for smoke detectors used in fire protection signaling systems and is intended for installation, inspection, and maintenance in accordance with applicable NFPA 72 requirements and local fire codes. Unlike the System Sensor 2W-B, which uses a two-wire initiating circuit for both power and alarm signaling, the 4W-B requires separate power and alarm connections. The related 4WT-B adds a 135 F fixed-temperature thermal sensor, while the 4WTA-B provides both thermal detection and an integrated 85 dBA audible sounder. The 4W-B does not include a Form C auxiliary relay, integrated horn, or heat detection functionality. Its combination of photoelectric smoke sensing, automatic drift compensation, dual-color visual diagnostics, low standby current, and prewired plug-in mounting makes it suitable for new conventional fire alarm installations and compatible detector replacements. System Sensor provides a three-year limited manufacturer warranty from the date of manufacture.