System Sensor 4WTA-B Photoelectric i3 Smoke Detector, 4-Wire, Thermal Sensor, Built-In Sounder

The System Sensor 4WTA-B is a 4-wire i3 Series photoelectric smoke and heat detector with a built-in 85 dBA sounder and 135 F fixed-temperature thermal sensor for compatible conventional fire alarm and security systems. Operating on nominal 12/24 VDC, it features 2.5%/ft nominal smoke sensitivity, automatic drift compensation, dual-color status LEDs, and a 41 F freeze trouble indication. The detector draws 50 A in standby and up to 35 mA during alarm, supports synchronized temporal-three audible signaling through an optional RRS-MOD module, and includes a prewired mounting base with Stop-Drop 'N Lock installation technology.

System Sensor 4WTA-B i3 4-Wire Photoelectric Smoke and Heat Detector with Sounder

The System Sensor 4WTA-B is a conventional four-wire photoelectric smoke detector with an integrated 135 F (57.2 C) fixed-temperature heat sensor and an 85 dBA audible sounder designed for compatible residential and commercial fire alarm systems. Part of the System Sensor i3 Series, the 4WTA-B combines smoke detection, thermal sensing, and local audible notification within a single ceiling- or wall-mounted assembly. Its advanced photoelectric sensing chamber detects airborne smoke particles, while the self-restoring fixed-temperature thermal sensor provides an additional method of identifying fire conditions when the specified temperature threshold is reached. The detector incorporates an audible sounder that produces a temporal-three evacuation signal conforming to ANSI S3.41, providing local notification when the detector activates. Designed for conventional fire alarm and compatible security control panels, the 4WTA-B is suitable for homes, apartment buildings, offices, retail establishments, and other indoor occupancies requiring integrated smoke and heat detection with audible alarm signaling.

The 4WTA-B operates on nominal 12 or 24 VDC power with an operating voltage range of 10-35 VDC, using separate power and alarm circuit connections. Its low-power electronic circuitry draws approximately 50 microamps during normal standby operation and up to 35 mA during alarm, supporting integration with appropriately rated conventional alarm panels and power supplies. The photoelectric sensing chamber provides a nominal smoke sensitivity of 2.5% obscuration per foot and incorporates microprocessor-controlled drift compensation and smoothing algorithms that automatically adjust sensitivity as environmental contaminants accumulate within the chamber. These features help maintain consistent smoke detection performance while reducing unwanted alarms associated with gradual dust buildup and transient environmental interference. The detector includes a 41 F (5 C) freeze trouble feature that identifies temperatures below its recommended operating range. Dual-color status LEDs provide operating and diagnostic information, with a flashing green indicator during normal standby, a solid red indicator during alarm, and distinctive red flashing patterns for out-of-sensitivity and freeze trouble conditions. Its normally open alarm contacts are rated at 0.5 amps at 30 VAC/DC for connection to the conventional initiating device circuit.

The System Sensor 4WTA-B incorporates an 85 dBA piezoelectric horn that produces a temporal-three audible evacuation pattern during a local alarm condition. When connected through the optional System Sensor RRS-MOD reversing relay and synchronization module, compatible i3 Series sounder detectors on the same circuit can activate together when an alarm occurs. The RRS-MOD reverses the detector supply polarity to trigger the sounders, synchronizes their audible patterns, and supports alarm silencing through a compatible fire alarm control panel. The 4WTA-B also features a Stop-Drop 'N Lock plug-in mounting system that allows installers to complete base wiring before attaching the detector head. The included mounting base accommodates 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 accept 14-22 AWG conductors, providing flexible wiring connections for compatible installations. An optional tamper-resistant locking feature helps prevent unauthorized removal, while the removable cover and replaceable insect screen simplify routine cleaning and servicing. The detector also supports sensitivity measurement using the separately available System Sensor SENS-RDR infrared sensitivity reader.

The System Sensor 4WTA-B measures 5.3 inches in diameter and 2 inches high (134 x 51 mm), including its mounting base, and weighs approximately 7.1 ounces (200 grams). It operates in ambient temperatures from 32 F to 100 F (0 C to 37.8 C) and supports relative humidity from 0% to 95%, noncondensing. The 4WTA-B is UL 268 Listed for smoke detection in fire protection signaling systems and is intended for installation, testing, and maintenance in accordance with applicable NFPA 72 requirements and local fire safety codes. Unlike the System Sensor 4WTR-B, which includes a Form C auxiliary relay without an audible sounder, the 4WTA-B provides local audible notification without that additional relay. The related 4WTAR-B combines both an 85 dBA sounder and a Form C auxiliary relay, while the 4WITAR-B provides an isolated thermal sensing configuration for applications requiring different alarm responses. The 4WTA-B is not an addressable detector or a standalone battery-powered smoke alarm; it requires compatible hardwired control equipment for system monitoring. Its combination of photoelectric smoke detection, 135 F thermal sensing, integrated audible notification, automatic drift compensation, low standby current, and synchronized sounder compatibility makes it suitable for new conventional fire alarm installations and replacement applications.