Nest Protect vs First Alert SC5

What actually happened

Google stopped producing the Nest Protect in March 2025, and announced a connected life-safety partnership with First Alert. Existing units continue to receive software and security updates, and Google directs owners looking for a replacement to the First Alert SC5 Smart Smoke & Carbon Monoxide Alarm.

The migration was designed rather than improvised, which is worth acknowledging. The SC5 mounts on the Nest Protect's existing bracket, includes a quick-connect adapter for hardwired Nest positions, and works with the Google Home app — so the transition does not require rewiring, new plates or a different app ecosystem.

That is a considerably better outcome for owners than most discontinued smart-home hardware gets.

Quick picks

Scored against currently sold, replaces a nest cleanly, listing coverage, away notifications and upkeep over ten years. Tap a row for the full write-up. No price is shown anywhere on this site because we do not cache retailer prices.

#	Product	Best for	Score	Price
1	First Alert SC5 Smart Smoke & Carbon Monoxide Alarm Google's promoted successor, on the bracket already in your ceiling.	Replacing a Nest Protect	9.4/ 10	Check price on Amazon #ad how we are funded · we do not cache prices
2	Google Nest Protect (2nd generation) Discontinued in March 2025. Keep using it until its date; do not buy one.	Owners of existing units	4.6/ 10	Check price on Amazon #ad how we are funded · we do not cache prices

The two units in full

Illustrative photo

1. Replacing a Nest Protect

First Alert SC5 Smart Smoke & Carbon Monoxide Alarm

Google's promoted successor, on the bracket already in your ceiling.

Listed to

UL 217 and UL 2034

Sensing / agent

Photoelectric smoke sensing plus an electrochemical CO cell

Power / service life

10-year sealed battery

Currently sold10.0

Replaces a Nest cleanly9.5

Listing coverage9.0

Away notifications9.5

Upkeep over ten years9.0

Overall9.4/ 10

The practical value here is the bracket. First Alert's compatibility guidance confirms the SC5 mounts on the existing Nest Protect bracket and ships a quick-connect adapter for hardwired replacements — which turns a four-unit house from one expensive weekend into four separate five-minute jobs as each unit ages out.

Feature-wise you are getting the things people actually used the Nest for: both listings, a ten-year sealed battery, phone alerts when nobody is home, and app integration through Google Home. The away notification is the one genuinely valuable smart feature, and it survives the transition.

What you should notice is that this is a move from one ecosystem-dependent product to another, and the reason you are making it is that the first ecosystem stopped making the hardware. That is not an argument against the SC5 — it is a good reason to buy your *required coverage* in plain or interconnected alarms and reserve the smart units for positions where the away notification earns its cost.

What it does well

• +Currently produced and supported, which the Nest Protect is not
• +Reuses the Nest Protect mounting bracket, so a staged swap needs no new plates
• +Includes a quick-connect adapter for hardwired Nest positions
• +UL 217 and UL 2034, a 10-year sealed battery, Google Home app integration and phone alerts

The downside

• −Wi-Fi and app dependency for its distinguishing features
• −You are moving from one ecosystem-dependent product to another
• −Higher cost per position than a plain listed alarm

Do not buy this if: you have concluded that a life-safety device should not depend on a cloud service at all — a reasonable conclusion after this episode. In that case buy interconnected non-smart alarms instead; [the main roundup](/smoke-detectors/best-smoke-detectors) covers them.

• Works with the Google Home app; Google promotes it as the Nest Protect replacement
• Reuses the Nest Protect mounting bracket, and ships a quick-connect adapter for hardwired swaps
• Interconnects with existing Nest Protect units during a staged changeover
• Phone alerts when the alarm sounds away from home

First Alert product documentation

Check price on Amazon

#ad how we are funded · we do not cache prices

Illustrative photo

2. Owners of existing units

Google Nest Protect (2nd generation)

Discontinued in March 2025. Keep using it until its date; do not buy one.

Discontinued. This is here for owners of existing units, not as a current purchase.

Listed to

UL 217 and UL 2034

Sensing / agent

Split-spectrum smoke sensing plus an electrochemical CO cell

Power / service life

Manufacturer-stated 10-year unit life; production ended March 2025

Currently sold0.0

Replaces a Nest cleanly10.0

Listing coverage9.0

Away notifications8.5

Upkeep over ten years4.0

Overall4.6/ 10

If you own Nest Protects, the honest advice is: do not rush. Google ended production in March 2025 and has continued software and security updates for existing units, which is the responsible way to wind a product down. Your alarms are still listed alarms and they still work.

What changes is the end-of-life plan. The ten-year clock runs from each unit's own manufacture date, not from the discontinuation announcement, so check the dates on the back and plan replacements accordingly. When to replace covers where the date is.

Do not buy used Nest Protects. Whatever the price, you are buying an unknown fraction of a ten-year service life in a device nobody is making spares for, and on a life-safety product that is a bad trade.

It was a good alarm. It is not a purchase.

What it does well

• +UL 217 and UL 2034 — it was and remains a properly listed alarm
• +Split-spectrum smoke sensing plus an electrochemical CO cell
• +Spoken alerts naming the room, plus phone notifications
• +Google has continued software and security updates for existing units

The downside

• −**Production ended in March 2025.** It is not a current purchase
• −Buying one second-hand means buying an unknown remaining service life
• −The manufacturer-stated ten-year unit life still applies from its own manufacture date

Do not buy this if: anyone shopping for a new alarm. It is on this page for owners of existing units, not as a recommendation. If you find them cheap somewhere, the service-life clock started at manufacture and you have no idea how much of it is left.

• Google stopped producing it in March 2025 — it is no longer a current purchase
• Existing units continue to receive software and security updates
• Spoken alerts that named the room, plus phone notifications
• The First Alert SC5 is the successor Google itself points owners toward

How to do the changeover

There is no urgency, and that is the most useful thing on this page. Plan it around the dates rather than around the announcement.

1. 01

   Read the manufacture date on the back of every Nest Protect

   The ten-year clock runs from each unit's own manufacture date. That tells you the actual replacement schedule, which may be spread over several years.

2. 02

   Confirm the app and the alarms still work

   Press the test button on each unit, and check they still appear and report in the app. Existing units continue to receive software and security updates.

3. 03

   Count your positions against the requirement while you are at it

   One per sleeping room, one outside each sleeping area, one per level including the basement. A Nest house is often under-covered because the units were expensive. How many do I need.

4. 04

   Replace the oldest unit first, on the existing bracket

   The SC5 mounts on the Nest bracket, and the quick-connect adapter handles hardwired positions. One unit, one position, no rewiring.

5. 05

   Let the mixed set interconnect during the transition

   First Alert's guidance is that the SC5 works alongside existing Nest Protect units, which is what makes a staged changeover viable rather than all-or-nothing.

6. 06

   Decide whether every position needs to be smart

   The away notification is the feature worth paying for, and it does not need to be at every position. Plain or interconnected alarms in the bedrooms plus a smart unit at the main hub is a cheaper and more robust arrangement. Smart alarms.

7. 07

   Record the new dates

   Write down each new unit's manufacture date so the next cycle is a five-minute check. The home fire safety checklist.

The lesson worth taking from this

A well-supported smart alarm from one of the largest technology companies in the world stopped being made. Google handled the wind-down about as well as it could be handled — continued updates, a designed migration, bracket compatibility — and it still means every owner has a hardware transition to plan that a plain alarm would never have required.

The reasonable conclusion is not 'never buy smart alarms'. It is buy your required coverage in devices that depend on nothing, and add smart capability where it does something a dumb alarm cannot.

Concretely: interconnected listed alarms in every required position, which give you whole-house sounding with no app, no account and no service to discontinue — plus one or two smart units where the away notification matters. Then a discontinuation costs you a feature rather than your alarms.

Interconnected smoke alarms covers the wired and wireless routes, and the main roundup has the picks.