Product Library / Security Systems & Alarms

First Alert SC5 Smart Smoke & Carbon Monoxide Alarm

Compiled by SmartHomeWorkflow Research · First Alert · Security Systems & Alarms · ~$130 ($129.99 on First Alert's own store, re-verified 2026-08-12 — unchanged from the recorded MSRP and never treated as a live price. ⚠ AVAILABILITY CHANGED at the same read: the hardwire SKU (FSMCO600NVACCL1 / model SMCO600NV-AC) shows as unavailable, backordered on First Alert's own page. That is a stock state on a date, NOT a discontinuation — the product is still listed, priced and described, and First Alert has said nothing about ending it.)

Compatibility

? Inconclusive means we researched that ecosystem and the evidence doesn’t settle it — the catch says why, and the sources are listed below. It is a statement about the available evidence, never a verdict on the product. A Setup Check researches your exact setup where the official sources don’t answer.

Protocols: WIFI^[4][7]

What it can do^[9]

Listed capabilities are what we could establish from vendor documentation. An ability missing here is unestablished — not necessarily absent.

Subscription reality^[18]

✓ Works without a subscription: Yes.

Vendor account required: Not established — we have not sourced this yet.

No paid plan found for any alarm function. Free accounts are required (a First Alert account, plus a Google Account for Google Home), but nothing is behind a paywall.

Maintenance reality

• Batteries: 6× CR123A 3V lithium, replaceable (battery model); 120V AC with lithium backup (hardwire model)
• Works without the internet: Partly — some of it keeps working and some of it does not. See the detail below.^[1]
• Ten-year end-of-life signal from installation, matching the mandated sensor lifespan; 10-year limited warranty. Seven-day low-battery warning. Local alarming, the sounder, and both wireless and hardwire interconnect are device-side and survive an internet outage; push alerts, remote test/silence and Google Home all need Wi-Fi plus Resideo's cloud. First Alert's own two pages disagree on whether the hardwire model's backup battery is replaceable — recorded as unresolved rather than picked.

Security updates^[10]

First Alert publishes no security-update support date for this model. That is a gap in what the manufacturer has published, not evidence either way — some makers declare a support period and some say nothing at all.

Verified absence, earned by walking the rungs rather than defaulted. Resideo publishes no security-update period for this product, on its product-security page, its vulnerability-disclosure page, or the product's own page. What Resideo does publish is more revealing than silence: its two end-of-support events were both driven by a CERTIFICATE EXPIRING rather than by a support window running out. So the practical horizon for a Resideo connected product is the life of a PKI certificate nobody publishes the expiry of, and the vendor's own precedent is that when one lapses the device stops being installable. That is a different and less predictable shape than a stated period, and it is why this absence is recorded with the precedents attached. Recheck condition: Resideo publishes end-of-support notices on honeywellhome.com; a notice naming this model converts this cell into a date.

The catch

This is the alarm Google points Nest Protect owners toward, and it talks to Google Home and almost nothing else. The Onelink generation it replaced had genuine Apple HomeKit support; First Alert now states the SC5 does not, and SmartThings is ruled out in writing too. An Apple Home or Alexa household gets a Wi-Fi alarm that reaches the First Alert app and Google Home only.

Who it's for

Google Home households, and Nest Protect owners looking at the successor Google itself names — the two interconnect. Households on Apple Home, Alexa or SmartThings should note that all three are documented as unsupported.

Sources & method

Numbered sources below back the facts marked with the matching number above. This is a research profile: compiled from manufacturer documentation, certification registries, and published testing — we state facts, not verdicts, and we have not physically tested this unit. How we work →

Compatibility and lifecycle information reflects the last-verified date above and can change without notice (firmware updates, cloud-service changes, discontinuations). It is provided as-is, for information — verify with the manufacturer before purchasing. Spot an error? Tell us and we'll fix it. Full terms: Terms of Service.

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