The Clocks Just Fell Back: The One Safety Check Firefighters Ask Every Home to Do
Fire departments use the end of daylight saving time as a reminder to test smoke and carbon monoxide alarms. Here is exactly what to check, and what has changed.
By Daniel HartmannHardware Reviewer
Daylight saving time ended in most of the United States at 2 a.m. on Sunday, November 1, 2026. Hawaii and most of Arizona do not change their clocks. As every autumn, fire departments across the country published the same reminder: while you change your clocks, test your smoke and carbon monoxide alarms.
It sounds routine, but the numbers explain why firefighters keep repeating it. According to the National Fire Protection Association (NFPA), nearly three out of five home fire deaths in the US happen in homes with no smoke alarms (43%) or with alarms that did not work (16%). The death rate is about 60% lower in homes with working alarms.
The most common reason an alarm fails is simple: a missing, disconnected or dead battery. That is the part you can fix in a few minutes.
The 10-minute check
- Press the test button on every alarm, smoke and carbon monoxide, until it sounds. If it doesn't, replace the battery or the alarm. The NFPA and the American Red Cross recommend testing once a month, not only when the clocks change.
- Check what kind of battery it has. This is the part many people get wrong (see below).
- Look for the manufacture date on the back or side of each smoke alarm. Replace any alarm that is 10 years old or older, even if it still beeps when tested.
- Check the carbon monoxide alarms' dates too. They also wear out, and the lifespan depends on the model, so follow the date or instructions printed on the unit.
- Count your alarms (see "Where alarms belong" below).
- Agree on an escape plan. The Red Cross recommends practising it at least twice a year, with two ways out of every room and a meeting point outside.
"Change your clocks, change your batteries" is now only half right
The famous slogan dates from a time when almost every alarm used a replaceable 9-volt battery. Today, many alarms have a sealed 10-year battery. The NFPA, which notes that it did not create the slogan, gives this guidance:
- Sealed 10-year battery: do not try to open it or change the battery. When it chirps to warn that the battery is low, replace the whole alarm right away.
- Any other battery: replace it at least once a year, and immediately if the alarm chirps.
- Use the battery type the manufacturer lists on the alarm. A different battery may stop it from working properly.
Hardwired alarms also need attention. They usually have a backup battery that keeps them working during a power cut, so check that too.
Where alarms belong
Many older homes don't have enough alarms for today's rules. The NFPA recommends smoke alarms:
- inside every bedroom,
- outside each sleeping area, such as in the hallway,
- on every level of the home, including the basement.
The NFPA also recommends interconnected alarms, so that when one sounds, they all sound. That matters because modern furniture burns fast. According to the NFPA, you may have as little as two minutes to get out once an alarm sounds.
A smoke alarm with a dead battery is just a plastic disc on the ceiling. The check takes ten minutes; set a monthly phone reminder and you never have to remember the clocks again.
If an alarm keeps going off by mistake
Never remove the battery to silence an alarm that sounds while you are cooking. That is how many alarms end up not working. Instead, ventilate the room and press the "hush" button if it has one. If false alarms keep happening, move the alarm a little further from the kitchen or bathroom, following the manufacturer's instructions.
Quick checklist
- Test every smoke and CO alarm: monthly.
- Replaceable batteries: at least once a year.
- Sealed 10-year alarm chirping: replace the whole unit.
- Smoke alarm 10 years old or older: replace it.
- One in every bedroom, outside sleeping areas and on every level.
- Escape plan practised twice a year.
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