Kidde Home Safety 21006378 85 dB 120 Volt 9 Volt Battery AC/DC Ionization/Photoelectric Wire-In Smoke Alarm
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Manufacturer Kidde Smke Detectors
Mfg Catalog # 21006378
Irby Part # 3185789


  • Ionization Sensing Technology
  • One button design (operates Hush™ and test).
  • Large mounting base.
  • 9V Battery Backup (included).
  • Tamper resist feature.
  • Alarm memory.
  • Pre-stripped wiring harness with tinned strands.

Key Features

Easy Installation

  • Front battery pull tab allows battery activation without removing alarm from mounting bracket.
  • Large mounting base makes mounting easier, protects surface paint from dirt and covers imperfections.
  • Pre-stripped wiring harness with easy off cap does not require stripper tool. Tinned strands increase conductivity and wire nut grip.

Fewer Callbacks

  • One button design for easy operation and less confusion. Operates Hush™ and alarm test.
  • Battery run down protection will shut down alarm memory when AC power is not present, reducing low battery chirp.
  • Dust cover protects sensor from contaminates during construction reducing nuisance alarms.

User-Friendly Features

  • Tamper resist locking feature deters alarm theft.
  • Alarm memory flashes red LED indicating which unit was the initiating alarm in interconnected system.
  • Interconnectable with up to 24 devices (of which 18 can be initiating) including smoke, CO and heat alarms. See user’s guide for complete instructions.


Technical Specifications

  • Model Number: i12040A
  • UPC: 0-47871-40381-3
  • Power Source: 120VAC (80mA) with 9V Battery Back Up
  • Sensor: Ionization
  • Audio Alarm: 85dB at 10ft
  • Temperature Range: 40˚F (4.4˚C) to 100˚F (37.8˚C)
  • Humidity Range: 5%-95% relative humidity (RH)
  • Size: 5.6” in diameter x 1.55” depth
  • Weight: .5lb
  • Interconnects: Up to 24 Kidde devices
  • Wiring: Quick-connect plug with 8” pigtails
  • LED: Red, 4 modes of operation, Green , indicates AC power
  • Warranty: 10 year limited

Architectural and Engineering Specifications

The smoke alarm shall be Kidde model i12040A or approved equal. It shall be powered by a 120VAC, 60Hz source along with a 9V battery backup. The unit shall incorporate an ionization sensor with nominal sensitivity of .50 to 1.28%ft. The temperature operation range shall be between 40˚F and 100˚F (4˚C and 38˚C) and the humidity operating range shall be 5% - 95% relative humidity. The smoke alarm can be installed on any standard single gang electrical box, up to a 4” octagon junction box. The electrical connection (to the alarm) shall be made with a plug-in connector. A maximum of 24 Kidde devices can be interconnected in a multiple station arrangement. The interconnect system must not exceed the NFPA (National Fire Protection Association) limit of 18 initiation devices, of which 12 can be smoke alarms. With 18 initiating devices (smoke, heat, CO, etc.), interconnected, it is still possible to interconnect 6 strobe lights and or relay modules. The unit shall provide optional tamper resistance that deters removal of the unit from the wall or ceiling. The alarm shall include a test button that will electronically simulate the presence of smoke and cause the unit to go into alarm. This sequence tests the unit’s electronics, battery and horn to ensure proper operation. The unit shall include a piezoelectric horn that is rated at 85 decibels at 10 feet. The unit shall include HushTM feature that silences the unit for approximately 7 minutes if a nuisance condition occurs. The unit shall also include a low battery warning utilizing a brief alarm chirp every 40 seconds for a minimum of seven (7) days. The unit shall incorporate red and green LED indicators. The green LED (when illuminated) indicates the presence of AC power. The red LED (located under the TEST/Hush button) has four modes of operation: Standby Condition: The red LED will flash every 40 seconds to indicate that the smoke alarm is operating properly. Alarm Condition: When the alarm senses products of combustion and goes into alarm the red LED will flash one flash per second. The flashing LED and pulsating alarm will continue until the air is cleared. When units are interconnected, only the red LED of the alarm that senses the smoke or is being tested (the originating unit) will flash. All other units in the interconnected system will sound an alarm but their red LED’s will NOT flash. Alarm Memory: This smoke alarm is equipped with an alarm memory, which provides a visual indication when an alarm has been activated. The red LED will illuminate for about 1.5 seconds every 20 seconds to indicate the memory condition. HushTM Mode: The red LED will illuminate for 1.5 seconds every 10 seconds, indicating the smoke alarm is in the HushTM Mode. The unit shall at a minimum meet the requirements of UL217, NFPA72, The State of California Fire Marshall, NFPA 101 (One and two family dwellings) Federal Housing Authority (FHA), Housing and Urban Development (HUD). It shall also include a 10-year manufacture’s limited warranty.

Installation of Smoke Alarm

  • The smoke alarm must be installed to comply with all local codes having jurisdiction in your area. All wiring shall be in accordance with articles 210 and 300.3(B) of the US National Electrical Code, ANSI / NFPA 70 and NFPA 72. The multiple station interconnect wiring must be in the same raceway as the AC power wiring. In addition the resistance if the interconnect wiring shall be a maximum of 10 ohms. Make certain all alarms are wired to a single, continuous (non-switched) power line, which is not protected by a ground fault interrupter. A maximum of 1000 ft. of wire can be used in the interconnect system. Use standard UL listed household wire as required by code.


The Kidde i12040A is an AC/DC powered, ionization smoke alarm that operates on a 120V power source with 9V battery backup. This alarm uses ionization sensing technology. Ionization sensing alarms may detect invisible fire particles (associated with flaming fires) sooner than photoelectric alarms. Photoelectric sensing alarms may detect visible particles (associated with smoldering fires) sooner than ionization alarms. Kidde strongly recommends that both ionization and photoelectric smoke alarms be installed to help insure maximum detection of the various types of fire that can occur within the home.

This smoke alarm is available in a 6-piece cut case with tray for easy display as well as a 6-piece bulk pack for contractors and property owners. This unit is a UL Listed product with a 10-year limited warranty.



User's Manual

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UPC 04787140381
GTiN 00047871403813
Warranty Length 10 yr
Operating Temperature 4.4 To 37.8 C
Diameter 5.6 in
Depth 1.55 in
Weight .5 lb
Operating Voltage 120 VAC
Family Brand Name Kidde
Power Source 120 V
Blade Dimensions 5.6 IN Diameter X 1.55 IN Depth
Loudness 85 DB At 10 FT
Environmental Conditions 5 to 95 PCT
Operating Frequency 60 HZ
Sensor Type Ionization
Sub Brand Firex

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