Difference Between 2 Wire and 4 Wire Smoke Detector for Alarm System

Difference Between 2 Wire and 4 Wire Smoke Detector for Alarm System

Your home or business alarm system protects both from intrusion, but often uses smoke detectors to provide protection against fire.  For low voltage alarm system smoke detectors, there are two basic wiring types.  2 Wire Smoke Detectors and 4 Wire Smoke Detectors.  Both do the same job but they connect differently.

Alarm smoke detectors are powered devices - they use the alarm system power (and battery) as a power supply.

2 Wire smoke detectors use the same wire pair to provide both power to the detector as well as carrying the signal back in case smoke is detected.  The wires connect to the PGM terminals on your alarm system.

4 Wire Smoke Detectors 2 wires to provide power from the security system auxilliary output connections.  They use a second set of 2 wires to connect to a zone input on the security system.  2+2=4 hence the term 4 wire.  They offer the advantage that the panel knows which detector has been triggered in case of a fire (or false alarm).

We have a selection of 2 wire and 4 wire detectors for alarm systems here:
     https://www.aartech.ca/smoke-detector

As an example, FSA-210AST or 528B would be 2 wire detectors and FSA-410AST or 541NB or 2012J would be 4 wire detectors.  We may show others on the site as well.

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