Kidde P12040 Hardwired Photoelectric Smoke Alarm
- 120VAC hardwired, 9V battery backup included
- Photoelectric sensor for smoldering-fire particles
- Up to 24 Kidde devices interconnected
- 85 dB at 10 feet piezoelectric horn
- 40 to 100 F operating range, 5 to 95% humidity
- Red and green LEDs show status and AC power
- 5 year limited warranty per specs, 10-year per description
Last refreshed Sep 8, 2026 · Based on the Amazon listing and published specifications, not hands-on testing.
A straightforward hardwired photoelectric alarm with battery backup and wide interconnect support, suited to replacing or extending a wired system. Kidde itself advises also installing ionization alarms for flaming fires.
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ASIN: B000P511TYModel: P12040Category: Smoke Detectors & Fire Alarms
Overview
A photoelectric sensor inside watches for the visible particles that smoldering fires give off, and a piezoelectric horn sounds when it trips. The alarm runs on household AC power with a battery that takes over during an outage, and it can stand alone or link to other Kidde units.
Kidde built this unit for wired homes: a plug-in power harness speeds up installation and a pull tab means the backup battery is ready from the start. On its own it may react later to fast flaming fires, which is why Kidde recommends pairing it with ionization alarms.
Who it's for
Homes with an interconnected wired system get a photoelectric alarm that can join the chain. Renters or owners without AC wiring at the ceiling should look at a battery-only alarm.
Pros and cons
- Battery backup during power outages
- Battery pull tab, no install step
- Quick connect power harness
- Test button checks electronics, horn and battery
- Needs AC wiring, not a battery-only install
- Warranty length conflicts across the listing
- No ionization sensing for flaming fires
- Specs field calls it battery powered
Performance notes
Detection speed depends on fire type: the photoelectric chamber reacts to visible smoke from smoldering fires, while flaming fires with finer particles may trip an ionization alarm sooner. Coverage across the house depends on interconnection with other Kidde units. The backup battery carries it through power cuts.
Specifications
| Brand | Kidde |
|---|---|
| Model | P12040 |
Frequently asked questions
What size electrical box does the Kidde P12040 mount on?
It installs on any standard single gang electrical box, up to a 4 inch octagon junction box.
Does the Kidde P12040 detect flaming fires quickly?
It uses only a photoelectric sensor, which may detect smoldering fires sooner. Kidde recommends also installing ionization alarms, which may detect flaming fires sooner.
How many smoke alarms can share one interconnected Kidde system?
Up to 24 Kidde devices can link, but the system must stay within the NFPA limit of 18 initiating devices, of which 12 can be smoke alarms. With 18 initiating devices linked, 6 strobe lights or relay modules can still be added.
How do I test the Kidde P12040?
Press the test button. It electronically simulates smoke and checks the electronics, horn and battery.
Can the Kidde P12040 work on its own?
Yes. It can run as a stand-alone unit or in an interconnected system.