System Sensor (4WTR-B) 4-wire, smoke/thermal detector with Form C relay

The System Sensor 4WTR-B is an i3 Series conventional smoke detector. It combines 4-wire photoelectric smoke sensing with a built-in 135°F fixed-temperature heat sensor. In addition, an onboard Form C relay supports local control or signaling.

This detector ships with its plug-in base included. As a result, installation stays fast and straightforward. Furthermore, the i3 design helps cut nuisance alarms on commercial fire alarm systems.

System Sensor 4WTR-B Detection and Relay

First, the photoelectric chamber detects the slow, smoldering fires common in commercial spaces. Then the fixed 135°F thermal sensor adds a second layer of protection. Also, the Form C relay drives auxiliary functions such as door release or fan control.

The 4WTR-B runs on 10 to 35 volts, non-polarized, over a 4-wire circuit. Standby current stays at 50 µA maximum. However, alarm current draws up to 35 mA.

i3 Maintenance Features

Dual-color LEDs report power-up, standby, alarm, and trouble at a glance. Specifically, the LED flags an out-of-sensitivity (drift) condition. In addition, the detector signals a freeze-trouble warning below 41°F.

Drift compensation and smoothing algorithms maintain stable sensitivity over time. Therefore, the 4WTR-B needs less frequent cleaning. For quick checks, the optional SENS-RDR reader displays sensitivity in percent-per-foot. Alternatively, the A77-AB2 bracket simplifies retrofit installs.

Specifications

• Type: i3 conventional 4-wire photoelectric smoke detector
• Thermal sensor: fixed 135°F (57°C), restorable
• Relay: one Form C, for local control or signaling
• Operating voltage: 10–35 V, non-polarized (4-wire)
• Standby current: 50 µA max
• Alarm current: 35 mA max
• Freeze trouble signal: below 41°F (5°C)
• Listing: UL 268

For more information, contact the Life Safety Consultants team at (888) 557-0558, or email us at: sales@lifesafetycom.com