# First Alert Onelink Replacement: Every Model Guide (2026) Canonical: https://buildingtalks.com/onelink-smoke-alarm-replacement/ > First Alert Onelink alarms are discontinued. Model-by-model replacements, hardwired and battery, HomeKit options, reviewed by a 30-year engineer. **Reader-supported:** As an Amazon Associate I earn from qualifying purchases, and some links go to eBay through its partner program. The picks are mine, affiliates don't pay for placement and don't shape what I recommend. ✓ Field Verified Reviewed by **Al, the Building Doctor** (IUOE Local 39 · 30-Yr Pro) · [Credentials & Standards ->](https://buildingtalks.com/about/) Model-by-Model Replacements for Discontinued Onelink Alarms · Field Tested Field Verified At a Glance: Onelink Replacement by Form Factor - **Hardwired Smart Onelink Gen 3:** Swap to the [First Alert SC5 Hardwired](https://buildingtalks.com/go?u=https%3A%2F%2Fwww.amazon.com%2Fs%3Fk%3DFirst%2BAlert%2BSC5%2BSmart%2BSmoke%2BCO) (~$130) — Exact physical fit, Google Home app support. - **Battery-Only Smart Onelink Gen 3:** Swap to the [Kidde Detect 30CUD10](https://buildingtalks.com/go?u=https%3A%2F%2Fwww.amazon.com%2Fs%3Fk%3DKidde%2B30CUD10%2Bsmoke%2BCO%2Balarm) (~$60) for zero-app value, or the First Alert SC5 Battery. - **Onelink Safe & Sound:** Separate the ceiling life-safety alarm ([SC5](https://buildingtalks.com/go?u=https%3A%2F%2Fwww.amazon.com%2Fs%3Fk%3DFirst%2BAlert%2BSC5%2BSmart%2BSmoke%2BCO) or [Kidde Smart](https://buildingtalks.com/go?u=https%3A%2F%2Fwww.amazon.com%2Fs%3Fk%3DKidde%2BSmart%2BSmoke%2Band%2BCarbon%2BMonoxide%2BAlarm)) from a bedside smart speaker. - **Apple HomeKit Users:** Use hardwired interconnected alarms (like Kidde 30CUD10) paired with an interconnect relay or Z-Wave listener bridge. ## What I swapped mine for I swapped my Onelink smart alarms for the [First Alert SC5 Smart Smoke + CO Alarm](https://buildingtalks.com/go?u=https%3A%2F%2Fwww.amazon.com%2Fs%3Fk%3DFirst%2BAlert%2BSC5%2BSmart%2BSmoke%2BCO) (hardwired in hallways) and [Kidde Detect 30CUD10](https://buildingtalks.com/go?u=https%3A%2F%2Fwww.amazon.com%2Fs%3Fk%3DKidde%2B30CUD10%2Bsmoke%2BCO%2Balarm) (sealed 10-year battery in bedrooms). **The swap itself.** For hardwired units, kill the circuit breaker, twist the old Onelink body counterclockwise off the mounting ring, and disconnect the 3-pin wiring harness. First Alert's SC5 base uses the same standard 4-inch ceiling electrical box spacing, so no new drywall holes are needed. Wire the new pigtail with 3 wire nuts (Black line hot, White neutral, Orange/Yellow interconnect), clip in the harness, and twist the alarm into the base. For battery-only bedrooms, back out two screws from the old bracket, mount the new bracket, and slide the alarm on to activate the 10-year internal battery seal. Expect 10 to 12 minutes per hardwired unit and 5 minutes per battery unit. **What carried over.** Instant physical interconnectivity (one triggers, all sound), dual photoelectric smoke detection, electrochemical carbon monoxide monitoring, and 85dB horn sirens. **What changed.** The biggest relief is abandoning First Alert's glitchy Onelink app, which suffered frequent pairing failures and hasn't received an iOS or Android update since December 2023. The SC5 pairs smoothly into the Google Home ecosystem, offering clear phone push notifications and self-testing logs. In secondary bedrooms where smart alerts aren't critical, dropping back to non-smart 10-year sealed Kidde units eliminated app maintenance entirely while remaining 100% compliant with NFPA 72 residential fire codes. **What it cost.** ~$130 for the smart SC5 hardwired hub, and ~$60 per unit for the 10-year sealed bedroom alarms. Zero contractor labor fees if you handle the screwdriver yourself. ## The short version If you're in a hurry **Match the mount, then pick the platform.** Hardwired Onelink goes to a hardwired replacement, battery Onelink goes to a battery one. Google Home house: the [First Alert SC5](https://buildingtalks.com/go?u=https%3A%2F%2Fwww.amazon.com%2Fs%3Fk%3DFirst%2BAlert%2BSC5%2BSmart%2BSmoke%2BCO). Alexa or Ring house: the [Kidde Smart Smoke + CO](https://buildingtalks.com/go?u=https%3A%2F%2Fwww.amazon.com%2Fs%3Fk%3DKidde%2BSmart%2BSmoke%2BCarbon%2BMonoxide%2BAlarm). No app at all: the [Kidde Detect 30CUD10](https://buildingtalks.com/go?u=https%3A%2F%2Fwww.amazon.com%2Fs%3Fk%3DKidde%2B30CUD10%2Bsmoke%2BCO%2Balarm). Apple HomeKit, which was Onelink's whole pitch: nothing native exists today, and the section below says what to do instead. ## Model by model: what you have and what replaces it | Onelink model | What it was | Replacement | | --- | --- | --- | | Safe & Sound (1039102) | Hardwired smoke + CO with a built-in Alexa speaker | Hardwired SC5 or Kidde Smart, plus an Echo Dot. Full guide [here](https://buildingtalks.com/onelink-safe-and-sound-replacement/). | | Smart Smoke + CO, hardwired (1042135) | Gen 3 Wi-Fi alarm, Alexa and HomeKit, hardwired with battery backup | Hardwired SC5 (Google) or hardwired Kidde Smart (Alexa, Ring) | | Smart Smoke + CO, battery (1042136, 1042138) | Gen 3 Wi-Fi alarm, battery pack, about 5 years | Battery SC5 or battery Kidde Smart. Non-smart: Kidde Detect 30CUD10 | | Wi-Fi hardwired, HomeKit (AC10-500) | First-gen Onelink, hardwired, HomeKit | Hardwired SC5 or Kidde Smart. HomeKit: see below | | Wi-Fi 10-year battery, HomeKit (DC10-500) | First-gen Onelink, sealed 10-year battery, HomeKit | Battery SC5 or Kidde Smart. Non-smart: Kidde Detect 30CUD10 | Every model on that table is marked discontinued on First Alert's own store. None of them stopped detecting smoke. What went away is the app, the firmware, and any promise of a fix if the Wi-Fi side breaks. ## First Alert Onelink replacement cost: Smart vs non-smart compared Replacing an interconnected residential smoke and carbon monoxide system involves calculating per-unit costs across your home's bedrooms, hallways, and living levels. Here is how modern smart alarms compare to standard NFPA 72 code-compliant 10-year alarms: Model | Power Source | Interconnectivity | Approx. Cost | Best Use Case | **First Alert SC5** | 120V Hardwire or 10-Yr Battery | Hardwire + Wi-Fi (Google Home) | ~$130 | Direct First Alert smart successor | **Kidde Smart Smoke + CO** | 120V Hardwire or 10-Yr Battery | Hardwire + Wi-Fi (Alexa/Ring) | ~$75 | Best for Alexa & Ring homes | **Kidde Detect 30CUD10** | 120V Hardwire + 10-Yr Backup | Hardwire (3-wire yellow pigtail) | ~$60 | Best non-smart / zero app headache | **First Alert BRK 3120B** | 120V Hardwire + Dual Sensor | Hardwire (3-wire orange pigtail) | ~$45 | Commercial dual sensor (Photo + Ion) | ## Step 1, find your manufacture date - **Pull the unit.** Twist counterclockwise. Hardwired models hang by the harness. Unplug the connector. - **Read the date on the back.** Add 10 years for the sealed-battery and hardwired models. The gen 3 battery pack is rated around 5 years, but the sensors still carry the 10-year rule. - **Map the timeline.** First-gen Onelink shipped around 2015, so the AC10 and DC10 units are at or past retirement now. Gen 3 shipped 2019 and runs to 2029. Safe & Sound shipped 2018, so 2028. Past 10 years is not a judgment call An AC10-500 from 2015 is done. Replace it this week, not when the smart features start to matter. ## Step 2, pick the right replacement path ### Path A, Google Home: First Alert SC5 When to take this path Your phones and speakers are Google. You want the same maker and the alarm Google itself endorses. - **What you get:** the [SC5](https://buildingtalks.com/go?u=https%3A%2F%2Fwww.amazon.com%2Fs%3Fk%3DFirst%2BAlert%2BSC5%2BSmart%2BSmoke%2BCO) in hardwired or battery form. Phone alerts, self-test history, remote silence, all in the Google Home app. It is the alarm Google named as the Nest Protect successor, so it is the one First Alert will support longest. - **Mounting:** ships with its own bracket. Two screws on the same box, same harness style for hardwired. Where to buy - [First Alert SC5 on Amazon](https://buildingtalks.com/go?u=https%3A%2F%2Fwww.amazon.com%2Fs%3Fk%3DFirst%2BAlert%2BSC5%2BSmart%2BSmoke%2BCO), check the current price. Match hardwired or battery to what you are removing. - [First Alert direct](https://www.firstalert.com/), multi-packs. ### Path B, Alexa or Ring: Kidde Smart Smoke + CO When to take this path You bought Onelink for Alexa. You are staying on Alexa or Ring. - **What you get:** the [Kidde Smart Smoke + CO](https://buildingtalks.com/go?u=https%3A%2F%2Fwww.amazon.com%2Fs%3Fk%3DKidde%2BSmart%2BSmoke%2BCarbon%2BMonoxide%2BAlarm), Wi-Fi, no hub, Alexa and Google. For Ring, the Ring-paired Kidde version from Home Depot. Hardwired and battery versions both exist. ### Path C, non-smart (the budget reset) - **Battery slot:** the [Kidde Detect 30CUD10](https://buildingtalks.com/go?u=https%3A%2F%2Fwww.amazon.com%2Fs%3Fk%3DKidde%2B30CUD10%2Bsmoke%2BCO%2Balarm), 10-year sealed combo. - **Hardwired slot:** a [First Alert hardwired smoke and CO combo with battery backup](https://buildingtalks.com/go?u=https%3A%2F%2Fwww.amazon.com%2Fs%3Fk%3DFirst%2BAlert%2Bhardwired%2Bsmoke%2Bcarbon%2Bmonoxide%2Balarm%2Bbattery%2Bbackup). Keeps the interconnect. ### Path D, Apple HomeKit (the hard one) There is no native HomeKit smoke and CO alarm right now Onelink was the HomeKit smoke alarm. With it gone, no current UL-listed combo alarm ships with native HomeKit. Two workable routes: a [First Alert ZCOMBO Z-Wave](https://buildingtalks.com/go?u=https%3A%2F%2Fwww.amazon.com%2Fs%3Fk%3DFirst%2BAlert%2BZCOMBO%2BZ-Wave%2Bsmoke%2BCO) alarm through a Z-Wave bridge that exposes it to HomeKit (Hubitat, Home Assistant, or a Homebridge setup), or a Matter-capable alarm when one ships. The Apple-only house should take Path C on the ceiling and accept phone alerts from a separate listener device until the market catches up. I will update this page when a real one exists. ## Step 3, execute the migration - **Breaker off for hardwired units.** Verify dead with a tester. - **Replace the whole set together.** Onelink units could talk to each other over their own wireless mesh. The first non-Onelink alarm breaks that mesh. Let the hardwire interconnect carry the job, and replace battery-only Onelinks with a wireless-interconnect family from one maker. - **Check manufacture dates on arrival.** Over 12 months old goes back. - **One at a time, test each,** then test the interconnect from one unit and listen for all of them. - **Delete the Onelink Home app** once the last unit is down. Nothing else depends on it. - **Recycle the old alarms.** Lithium cells inside. Best Buy, Home Depot, Lowe's. ## What NOT to do Don't buy "new" Onelink from a marketplace seller Sealed boxes are still listed. They are aged stock tied to a dead app, with years gone from the sensor clock. The AC10 and DC10 units on those listings may already be past their 10-year date in the box. Don't mix a battery alarm into a hardwired chain A battery alarm on a hardwired bracket does not interconnect. Match hardwired to hardwired. Don't leave a slot empty while you decide If the old unit still passes a test press and is under 10 years, keep it up until the box arrives. ## If you have an unusual setup ### Mixed Onelink generations in one house Common. A first-gen AC10 in the hall from 2015 and gen 3 battery units in bedrooms from 2020. The 2015 unit is past date. Replace the whole house as one set anyway, so the interconnect is one family and the retirement date is one date. ### Rental or multi-unit Landlords bought Onelink for the app. Replace with non-smart 10-year sealed units, Path C, and keep the app out of it. Tenants change, apps get orphaned, and a smoke alarm nobody can log into is a liability. ### Deaf or hard-of-hearing residents Bed-shaker accessory that pairs with the alarm. Lifetone HLAC151 and Kidde RemoteLync are UL 217 listed. ## Related diagnoses - [Onelink Safe & Sound replacement](https://buildingtalks.com/onelink-safe-and-sound-replacement/), the Alexa-speaker model, with the voice fix. - [Nest Protect replacement](https://buildingtalks.com/nest-protect-alternatives/), the other smart alarm that lost its maker. - [Best smart smoke & CO combo alarms 2026](https://buildingtalks.com/best-smart-smoke-co-combo-alarms-2026/), the full category ranked. - [Kidde Detect 30CUD10 review](https://buildingtalks.com/kidde-30cud10-review/), the non-smart pick in full. - [How to test a smoke alarm](https://buildingtalks.com/how-to-test-smoke-alarm/), the monthly, annual, and 10-year tests. - [Dropcam replacement](https://buildingtalks.com/dropcam-replacement/), shut off the same day as Nest Secure. - [All diagnoses: Reading the vitals](https://buildingtalks.com/) ## FAQ ### Is First Alert Onelink discontinued? Yes. Every Onelink model, the Safe & Sound, the gen 3 smart alarms in hardwired and battery form, and the first-gen AC10-500 and DC10-500, is marked discontinued on First Alert's store. The Onelink Home app has not been updated since December 2023. ### Do my Onelink alarms still detect smoke? Yes, until the 10-year date on the back. Detection and the hardwired interconnect are hardware. The app, firmware updates, and smart features are what went away. ### What replaces the Onelink hardwired smart alarm? The hardwired First Alert SC5 for a Google Home house, or the hardwired Kidde Smart Smoke + CO for Alexa or Ring. Both ship with their own bracket and use the same style of hardwire harness. ### What replaces the Onelink battery smart alarm? The battery First Alert SC5 or the battery Kidde Smart Smoke + CO. If you are done with apps, the Kidde Detect 30CUD10 10-year sealed combo. ### Is there a HomeKit replacement for Onelink? Not a native one. No current UL-listed smoke and CO combo ships with HomeKit. The workable route is a Z-Wave alarm through a bridge that exposes it to HomeKit, or a non-smart alarm on the ceiling until a Matter alarm ships. ### Can I keep using the Onelink Home app? It still opens for now, but it has had no update since December 2023. Do not build anything new on it. Delete it once the last Onelink unit is down. ### What does a First Alert Onelink replacement cost? Replacing a Onelink smoke and CO alarm costs ~$60 for a non-smart 10-year sealed combo like the [Kidde Detect 30CUD10](https://buildingtalks.com/go?u=https%3A%2F%2Fwww.amazon.com%2Fs%3Fk%3DKidde%2B30CUD10%2Bsmoke%2BCO%2Balarm), ~$75 for a [Kidde Smart alarm](https://buildingtalks.com/go?u=https%3A%2F%2Fwww.amazon.com%2Fs%3Fk%3DKidde%2BSmart%2BSmoke%2Band%2BCarbon%2BMonoxide%2BAlarm), or ~$130 for the flagship [First Alert SC5](https://buildingtalks.com/go?u=https%3A%2F%2Fwww.amazon.com%2Fs%3Fk%3DFirst%2BAlert%2BSC5%2BSmart%2BSmoke%2BCO). Because mounting brackets screw directly into standard ceiling boxes and use matching 3-wire pigtails, DIY installation takes 10 minutes with $0 contractor labor. 👨‍🔧 Al, The Building Doctor IUOE Local 39 Stationary Engineer · SFFD Fire Safety Director · 30+ Years Facilities Chief Al spent 30+ years as Chief Engineer managing 200,000+ sq ft commercial high-rises, Class A retail facilities, and complex residential mechanical plants. Every diagnostic guide and tool recommendation is grounded in real field failure patterns, NFPA codes, and union engineering standards. [Read Al's full background and editorial standards ->](https://buildingtalks.com/about/)