Today I installed some new Kidde PI2010 Hardwired Dual Photoelectric and Ionization Sensor Smoke Alarm with Battery Backup smoke alarms. I am interconnecting 5 of them in my home. When I hooked up the third one the other two went into alarm. I measured 120V on the red interconnect wire. Is this correct? I'm reading here that it should be 9V?

Any help would be appreciated.

  • white is 0V (neutral) , Blk is hot AC and Red is alarm , yes Red to White is DC , probably 0V for alarm (relay closed) Commented Sep 11, 2020 at 18:15
  • Can you provide a picture of the wiring?
    – MonkeyZeus
    Commented Sep 11, 2020 at 19:09
  • Can you post photos of the wiring at all alarms please? Commented Sep 12, 2020 at 1:12

1 Answer 1


Thank you all for comments. I was able to figure out the problem. Apparently the smoke alarm is polarity sensitive. Because of a wire change in the associated junction box, standard USA black and white was changed to British blue and brown. The brown is supposed to be connected to the black and white to blue, but they were reversed. Correcting this solved the problem. Now when the alarm is in "alarm mode" (test) it sends 18V on the red wire to the other alarms. and NOT have a constant 120V

  • Why do you have black/white (NEC) and blue/brown (IEC) colors in the same building? Where are you on this planet? Commented Sep 19, 2020 at 20:49
  • 3
    I am in The Caribbean on an island that is traditionally the British system and 220V. However my house is wired like an USA system and is 110V. While I can get most American fixtures and wires to purchase NO hardware store or electrical supplier on Island has American (black/white) romex type wire only the British brown/blue. So any exposed wire (surface mount) is British brown/blue. I plan to order this to have on hand for the next project. Southwire 28827421 25' 12/2 with ground Romex brand SIMpull residential indoor electrical wire type NM-B, White
    – Sean
    Commented Sep 24, 2020 at 1:33
  • 2
    Fascinating -- what do your local authorities use for wiring standards? Commented Sep 24, 2020 at 1:36
  • Good Question. I guessing a combination of both British and American depending on the application. I will ask.
    – Sean
    Commented Sep 24, 2020 at 1:39
  • I think uk power would not be split phase, but I assume that's what you must have? Ie 220 or 240 mains but then a panel with a neutral? Commented Nov 5, 2020 at 19:46

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