Reuben Saltzman

Smoke alarms, deadly differences

There’s a very good chance that the smoke alarms in your home won’t save your life in the case of a house fire. Nearly 3,000 people die every year in house fires, but approximately 2/3 of those deaths could be prevented simply by having the right type of smoke alarms.

If you don’t have photoelectric smoke alarms in your home, I urge you to install them. If you don’t know what type of smoke alarms you have, you probably don’t have photoelectric. I have yet to inspect a single new construction home with photoelectric smoke alarms. You heard that right, I’ve never seen it done, not once, in a new construction home.

I’m beating this drum, yet again, because we just had code guru Skip Walker on our podcast to talk about smoke alarms. I’ve blogged on this topic many times in the past, and I’m going to continue unapologetically blogging about it because this is a really big deal. If you want to hear why this matters so much, please check out our podcast on the topic.

For my cliff-notes version of the podcast, read on.

Deadly Differences

There are two main types of smoke alarms on the market, ionization and photoelectric. Ionization alarms were originally designed for warships during WWI to help detect fires on ammunition ships, which we can all agree would be a really bad thing. These devices use a small amount of radioactive material to ionize the air and will detect small changes in the electrical field created by small particles flowing through it, caused by flames. Ionization alarms are good at detecting fast flaming fires.

As it just so happens, ionization alarms are also very good at detecting burning food. These false alarms lead people to believe that their smoke alarms are extremely sensitive, and therefore extremely effective. This creates a false sense of security, yet also dramatically increases the risk of people removing or disabling their smoke alarms because they are frustrated by the frequent nuisance alarms. Intentional disconnects and non-functional alarms kill about 1,000 people per year.

Photoelectric smoke alarms, on the other hand, use a small chamber with light passing through it. If smoke particles obstruct the light, the alarm sounds off. I’m oversimplifying this concept, and this isn’t exactly how they work, but this is the best analogy I can come up with. This makes photoelectric smoke alarms good at detecting slow, smoldering fires.

Slow, smoldering fires are also very deadly fires. A good example would be a couch starting on fire. It sits and smolders for a very long time, completely filling a room with smoke, toxic chemicals, and carbon monoxide. The smoke gets so thick that you can’t see anything in front of you. A photoelectric smoke alarm will sound off very early with this situation, but an ionization alarm won’t sound off until it’s way too late, right as the couch is about to burst into flames.

Ionization alarms have about a 55% failure rate to save people in home fires. Can you believe that? I think this is crazy and horrible. Part of this dismal number is the failure of these alarms to sound off, and the other part is because people disable their alarms because of nuisance tripping.

On the other hand, photoelectric smoke alarms have a 96% success rate! So which one do you want in your home?

There’s a third type of smoke alarm available today, called optical smoke alarms. These essentially have two photoelectric sensors and are slightly better than straight-up photoelectric smoke alarms. Skip Walker says it’s not worth replacing your photoelectric smoke alarms because it’s such a small boost in performance. That, and a ton of these optical sensor smoke alarms were voluntarily recalled just recently.

Why don’t we have better rules?

Photoelectric smoke alarms aren’t new. They’ve been around for decades, yet most states don’t require them, and most people don’t install them because they cost just a little bit more money. And as I said at the beginning of this post, I’ve never seen a home builder install them. This is a business decision. It’s a matter of going with the least expensive, legal option available.

Skip shared some very disturbing information about the rule-making process for smoke alarm safety during our podcast. It seems that it’s just about impossible to get the rules changed for the public good when it comes to smoke alarm safety.

Take Action Today!

If you don’t know what type of smoke alarms you have in your home, check ‘em out. Give your smoke alarm a twist, pull it down and look at the label on the backside. It might say Photoelectric or Ionization, but if you don’t see either of those words, look for the word “radioactive”. That indicates an ionization alarm, or possibly a dual-sensor alarm.

And if your smoke alarm is over ten years old, replace it. If you can’t find a date on the back, it’s surely more than twenty years old and long overdue for replacement. You know what to do. Even if you have hardwired smoke alarms, it’s not that big of a deal to replace them. I made a short video clip showing how it’s done, check it out:

For more information, check out some of these related links:

12 responses to “Smoke alarms, deadly differences”

  1. Margaret chamberlain
    October 5, 2021, 11:18 am

    I love your posts and guests,Reuben. I learn something every week. My question about smoke detectors is what to do when the smoke detector goes off for no apparent reason? I thought one was faulty and causing it to go off but since I replaced that one, another one is “acting up”. They are hardwired photo electric. I replaced them all myself 2 years ago. Thanks for any insight!!!

  2. Reuben Saltzman
    October 5, 2021, 12:18 pm

    Hi Margaret, thank you for reading! The trick with photoelectric smoke alarms is to vacuum them periodically. Use your vacuum’s soft brush attachment. That should help to minimize the amount of “acting up.”

  3. Gregory Cotton
    October 5, 2021, 1:16 pm

    I’ve got a mix of both types, as they come up for replacement I’ll switch over yo all photoelectric.

    I’ve got them on all 4 floors but what I would do differently is run the 14/3 wire from each alarm to a box in the basement so I could isolate them when one goes off. A couple of switches and indicator lights would tell me which one is in alarm condition.


  4. Reuben Saltzman
    October 5, 2021, 2:29 pm

    Greg – once you do this, be sure to send photos. I’ve never seen anyone do something like that before.

  5. Tony Lovasco
    October 5, 2021, 2:25 pm

    Any recommendations on photoelectric smoke alarms that have some kind of visual indicator when the battery is low? Roaming around the house trying to figure out which one is beeping every 45 seconds is incredibly frustrating, and the ones with the 10 year batteries are still expensive enough to make them hard to justify when one has to replace a bunch of them at once.

  6. Reuben Saltzman
    October 5, 2021, 2:29 pm

    Hi Tony, sorry, no recommendations there. I’ve done the same thing numerous times, and I definitely feel your pain.

  7. Patty McDonald
    October 6, 2021, 10:54 am

    2 Questions:
    1. I was reading the transcript for the podcast and I am confused about the dual smoke alarms. First it sounded like they were really bad because they used an “and” logic for them to go off (had to be photo alarm and ionization alarm to go off) – but then it seemed like the new ones use an “or” logic, but I wasn’t sure I was understanding correctly. My alarms are dual as well as a CO2 detector. So are these good or are they worse than just having the photo alarm. I have these in 3 rental homes and I guess I’d rather spend the money on making it right than risk someone dying because I was too cheap.

    2. I’ve been reading the fronts and backs of the alarms and it does not mention photoelectric, ionization, or radioactive on them anywhere. 🙁 Is the next step just looking up the model number? I think that was listed.

  8. Reuben Saltzman
    October 6, 2021, 5:36 pm

    Hi Patty,

    1. Dual-sensor alarms have a higher potential for people to disable them because of false alarms from the ionization sensor. Assuming nobody has deactivated them, they should still sound off in time, however.
    2. I have yet to find an alarm that doesn’t have the word “radioactive” on the back if it’s an ionization alarm. But it’s fine print. I have several examples shown in this blog post, hopefully this will help:

  9. Michelle
    October 7, 2021, 9:43 pm

    There’s actually a 3rd type of “smoke” detector – heat detector for the garage.

    A facebook friend lost their house a year ago due to a faulty grill outside next to their garage; garage burned and then it got so big that once it hit the house (and smoke detectors) inside, it was too late. This summer I had an alarm that was beeping and I took the time to research about the heat detector.

    Do not buy the detectors with built-in batteries (smoke or CO), somehow those batteries fail after a few years and never reach the 10-years they claim. Instead buy photo-electric smoke detectors and get lithium batteries that will last longer (because we all know we aren’t replacing batteries on a yearly schedule). Photo electric nearest the kitchen will make a huge difference with cooking food, since I found this out about 15 years ago, I haven’t had one false alarm since then.
    Current building codes require detectors inside each bedroom; if you don’t have them, consider getting some installed (our house built in 1992 only required a detector in the bedroom hallway).

    Photo-electric and Ion type detectors will *not* work in our Minnesota garages, you need to look for “heat detector” alarm instead. I found and bought a hardwired one this summer and had it installed on the garage ceiling (sheetrock) so I don’t have to worry about it. I went on to my Google Calendar ten years from now with a reminder that all the detectors need to be changed.

    If I can share a website, it’s great for getting exactly what you want for detectors, I’ve purchased from them for over ten years and they also have the best prices:

  10. Reuben Saltzman
    October 8, 2021, 5:05 am

    Thank you for sharing, Michelle.

  11. David
    October 11, 2021, 4:24 pm

    Any reason to choose one brand over another? I see menards has a 2 pack of 9v battery-powered photoelectric for $10. Seems like a no brainer to switch over everything right away at that price, but are cheaper brands like that ok for smoke alarms? No need to cheap out if it can result in someone’s death

  12. Reuben Saltzman
    October 11, 2021, 7:43 pm

    Hi David, I don’t know of any difference in quality from one brand to the next. Odds are, you found a Kidde, First Alert, or BRK. They all make good products.

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