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Configuring devices on a Two‑Wire/ SAVwire Systems

FAQ- Which mounting base should be used? YBO-R/6PA.

Summary

This article explains how to configure detectors sounders/beacons and call points on a two-wire fire alarm system using the SAVwire (reverse-polarity) method and which mounting base to use for compatible detectors.

How two-wire (SAVwire) circuits work 

  • Two-wire SAVwire circuits use reverse-polarity signalling to drive sounders/beacons on the same pair of wires.
  • On systems that support two-wire/ SAVwire, sounders and beacons are wired on the two-wire detection circuit using reverse-polarity operation.
  • Detectors and call points are wired with normal polarity, when the system is activated the polarity is reversed on the circuit and the bridge rectifier within the detection base and call point keep the polarity correct.
  • Conventional (non two-wire) systems typically operate using zoned wiring and separate sound circuits rather than the two-wire reverse-polarity approach.

Panel compatibility

  • Confirm the fire alarm control panel explicitly supports two-wire SAVwire reverse-polarity operation before specifying or installing two-wire devices.
  • If the panel does not support the two-wire SAVwire method, the system will operate as a conventional zoned system with separate sound circuits instead.

Detector mounting bases for two-wire systems

  • Use a conventional detector mounting base designed for two-wire systems. The YBO‑R/6PA base is the specified conventional detector mounting base for two‑wire SAVwire installations.

Related device and wiring notes

  • The CCP-SAVwire is the specified call point designed for two-wire systems.
  • When replacing or specifying a panel and devices, state that you require a two‑wire SAVwire-capable panel so suppliers and installers select compatible equipment.
  • Ensure detectors sounders/beacons and call points are connected to the designated two‑wire reverse‑polarity circuit per the panel and device wiring instructions.

Conclusion

When the system is activated, the polarity on the circuit is reversed allowing the sounders and beacons to activate, whilst ensuring the detectors and call points remain operational.