Hardwire interconnect guide

Interconnect is a protocol + brand wiring problem — not a faceplate color problem.

Rules that prevent wrong buys

  • Stay on the same interconnect family unless an electrician reworks the circuit.
  • Kidde hardwire paths (e.g. KN-COSM-IBA) are not assumed compatible with First Alert.
  • Smoke-only units do not satisfy smoke+CO requirements.
  • Sealed 10-year battery units (e.g. i9010) are not hardwire interconnect replacements.

Before you shop

  • Photograph the model label on an existing alarm.
  • Note hardwire vs battery and whether a third interconnect wire is present.
  • Read the replace-by date — end-of-life chirps are not “low battery only.”