Wiring RC840T-120 Relay

Wiring RC840T-120 Relay

The Aube / Honeywell RC840T-120 relay provides two functions:

  1. Provide 24VAC power on the C and W terminals to power a low voltage thermosat
  2. Switch the 120V circuit when triggered by the low voltage R & W terminals

Take care to ensure you are not mixing high and low voltage wiring and that you are connecting to the correct thermostat terminals as needed.

Additionally this device should be installed by a professional and you must ensure that it is installed to any applicable code(s).

    • Related Articles

    • Connect a Siren Strobe or Strike to a Relay and Power Supply

      If you need to trigger a siren, strobe, or other device using a relay, you'll need to provide a power supply with enough capacity to run the siren and ensure you have a relay rated with sufficient capacity. The relay may be built into some other ...

    • Wiring / Connecting 2 Wire and 4 Wire Smoke Detectors to an Alarm System

      We are often asked how to connect low voltage smoke detectors to a wired alarm system.  First we need to point out that smoke detectors are a life safety product and so it's critical that you read and understand how the connection should work, and ...

    • Connect 120V wired smoke detectors to security alarm system like DSC, Vista, Concord

      We are often asked how to add 120V wired smoke detectors to a low voltage security alarm system like DSC, Vista, Concord or Elk. First we need to point out that smoke detectors are a life safety product and so it's critical that you read and ...

    • TH135-1 Relay Always Closed

      The TH135 relay latches in the last position in order to conserve battery power.  If the relay is closed when installing it will still open when commanded.

    • DSC RM-1 Wiring

      As of the time of writing (Aug 27th 2010) the RM-1 wiring is as follows: Black - negative coil Red - positive coil White - common Yellow - normally closed Green - Normally Open