Wiring & Connecting the Hardware: Wiring Smoke & CO Detectors

Do NOT rely on Konnected alarm panel alone for notifying you in an emergency.

Konnected alarm panel is not failproof, it depends on power, WiFi, and third-party software and services to function properly. Do not use Konnected alarm panel with life safety equipment like smoke and CO detectors unless you are sure they will alert you in an emergency even if Konnected alarm panel is not functioning.

Konnected is NOT certified to any national standards for smoke & fire safety monitoring equipment. Use is intended for informational purposes only for use with home automation software.

1. You may be able to connect your smoke detectors to Konnected so that you can monitor your home for smoke alarms via Smart Home Monitor or Home Assistant. Before doing this, consider a few things

  • How old are your smoke alarms?

    Smoke detectors should be replaced every 10 years according to the U.K. Fire Administration. Chances are pretty good that your smoke alarms are older than that. If they are, that’s OK. You may be able to replace them and re-use the wiring in the wall to connect them to Konnected Alarm Panel.

  • How were they connected to your old alarm panel?

    Examine the wiring from your smoke detectors to your old alarm panel. How many wires come into the panel cabinet from each smoke detector? Are they receiving power from the AUX output on your panel? There are a few different types of alarm system connected smoke detectors, and you will need to identify which type you have. Keep reading.

  • Do your smoke detectors have a built-in alarm?

    You MUST ensure that the smoke detectors will be able to alert you in an emergency via a built-in sounder. Some models of alarm system smoke alarms do not have a built in sounder, and these cannot be used with Konnected Alarm Panels.

  • Check local code requirements.

    Local fire and electrical code may require certain type of wiring or connection with external monitoring services. Konnected Alarm Panel is not a certified fire protection monitoring device and cannot be used to comply with such requirements.

2. Hardwired AC powered smoke detectors

Most newer construction in the United Kingdom are installed with hardwired smoke detectors that are powered by household AC current (with a backup battery) and have a wired interconnect so all stations alarm when smoke is detected. First AlertBRK, and Kidde are popular brands of this type in the U.K. You can connect this type of smoke detector circuit to Konnected Alarm Panel with a specialized relay module for your smoke detector model.

This is the safest way to connect smoke detectors to the Konnected alarm panel, because the relay module completely isolates the smoke detector power and signal from the Konnected alarm panel.

If you have this type of smoke detectors and they were previously connected to a zone on your old alarm panel, then you probably already have a relay installed. If not, here are a couple of relay modules for common interconnected smoke alarms.

Ei128R Hard Wired Relay Module

GIRA 2340 Relay

Connect the relay to the smoke alarm wiring according to the manufacturer’s instructions. Connect the NC and COM circuit of the relay to any zone on the Konnected alarm panel and set it up as a smoke detector device in your home automation app.

3. Low voltage smoke detectors

Some home security systems are connected to low voltage wired smoke detectors which are wired directly to, and powered by DC voltage from the alarm panel. Common brands of this category of smoke detectors are System SensorInterlogix/ESLDSC, and Bosch. There are generally two types of low-voltage smoke detectors: 2-wire and 4-wire configurations.

4. Two-Wire Smoke Detectors

Some traditional alarm systems panels are connected to 2-wire smoke detectors that are powered by a special smoke zone supplying supervised 12V power. 2-wire smoke detectors carry power and signal over the same pair of wires by using a special polarity reversing switch to indicate an alarm. Unfortunately, these will NOT work with the Konnected Alarm Panel.

2-wire smoke detectors will NOT work with the Konnected alarm panel. Remove your smoke detector from the wall/ceiling and inspect the wiring on the back of it. If you only see wires connected to two terminals on the back of the detector, it will NOT work with the Konnected alarm panel and must be replaced!

Popular smoke detectors models that fall into this category and DO NOT work with the Konnected alarm panel are System Sensor 2W-B, 2WT-B, COSMO-2W and Interlogix 521B, 528B. If you have this type of smoke detector, all hope is not lost! Inspect your wiring. If you have a 4-conductor wire running from your smoke alarm location to your alarm system panel location, you may be able to replace these with compatible 4-wire models.

5. Four-Wire Smoke Detectors

If your low-voltage smoke detectors have 4 separate wired connections on the back, then they may work with the Smart Home Alarms Panel without any additional equipment! These smoke detectors generally work just like motion sensors: 2 wires (red & black) supply 12VDC power, while a second pair of wires (any color) make a Normally Closed (NC) or Normally Open (NO) circuit to signal the Konnected Alarm Panel when smoke is detected. This signal circuit is often referred to as a Form C or Form A relay. Some smoke detectors of this type have both types of signal circuits, one intended for an interconnect and the other intended for an auxiliary relay or releasing device.

4-wire smoke detectors wired to the Konnected alarm panel will share power with the Konnected device, your other wired sensors, and siren. Ensure that you use the CE Certified 12V power supply that comes with your Konnected kit, and test that you have adequate power by sounding the siren and testing the smoke detector simultaneously. Also consider a backup battery to ensure that your smoke detectors still work in a power outage.

You can connect these smoke detectors to the Konnected alarm panel by connecting the red/black pair of wires to the AUX +/- respectively to power the smoke detector. Then, use the NC or NO signal pair to connect to any zone 1 – 6 on the Konnected alarm panel. By default, Konnected alarm panel assumes a NC circuit. If your signal circuit is NO, then change the setting to Normally Open in SmartThings after setting it up.

6. Recommended Replacements

If you have 4 low-voltage wires running from your alarm panel location to each smoke detector location and your smoke detectors need to be replaced due to age, incompatibility, or lack of built-in sounder, this model may serve as good replacements. All smoke detectors on this list meet the following criteria:


  • Built-in sounder (alarm) to notify you in case of an emergency.

  • Operate on 12VDC.

  • Built-in Form A or Form C relay for signaling the Konnected alarm panel.

ESP Fireline 12V Conventional Optical Smoke Detector

Testing Smoke Detectors

It is critical that you test your smoke detectors after re-wiring. Do not just assume it’s working!


  • Follow the smoke detector’s instruction manual for testing procedure. Ensure that the sounder sounds and that Konnected is properly signaled in an alarm.

  • Use canned smoke or very carefully use real smoke to test the smoke detection capability. Some detectors with heat detection capability can also be triggered with a hair dryer on the hottest setting.

  • Test the maximum power of the system by triggering the siren and the smoke alarms at the same time. Ensure that the system does not shut down due to insufficient power.

  • If you have multiple interconnected smoke detectors, ensure that they all alarm when one alarms.

  • Test a power failure scenario and ensure that the smoke alarms still operate and notify you when power is out.