Are smoke alarms reliable?

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Old 03-27-13, 10:20 AM
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Are smoke alarms reliable?

Something that we depend on to alert us to a fire in our home should be dependable but all I'm reading is BAD. They go off fine on burnt toast but can I bet my life that it will go off on a REAL fire in time to waken me so I can get my family out before injury?

Where are the facts & tests on these things that are mandatory in new construction? From a quick Google search it appears for every test that shows they work quickly and reliably there is one that shows they wait til you're dead before sounding the alarm (if ever) :-/
 
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Old 03-27-13, 10:33 AM
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As you know, there are two basic types. One works best for an active blaze and the other is better at sensing smouldering fires.

Now a few detectors are being built to detect both.

You can't bet your life that seat belts or air bags will properly deploy and save you in every situation but odds are they will reduce the risk. Same with smoke detectors.
Most reports I've seen where a smoke detector failed to go off was because it had no battery.
 
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Old 03-27-13, 01:14 PM
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It amazes me that years after local building codes mandated the installation of several in new homes that the jury is still out on how reliable they are. Yes they are better than nothing--but how much better? A number I see often is 2X as good as no alarm. With the odds of escaping a night-time home fire unharmed being as low as 10% doubling that to 20% isn't going to help me sleep at night.

From what I've seen Googling the issue Texas A&M has done the most extensive testing on alarms in actual house fire conditions (not with canned smoke that's designed to be ideal). Here's a good concise article:
Today article on smoke alarm failures

A 2011 101-page report by the National Fire Protection Association quoted a CPSC study that found that even new interconnected AC-powered, battery-backup units only alarmed 53% of the time. That's their BEST-CASE scenario. Battery-powered, un-interconnected ones did worse.

Pleasant dreams...
 
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Old 03-27-13, 02:11 PM
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The reliability of a smoke alarm alerting in the presence of a fire has as much to do with the location of the alarm unit as it does the technology of that unit. Since it is impractical to install a smoke alarm over every square foot of wall or ceiling surface they need to be installed in areas that are more likely to have the smoke of a fire collect, or at the very least, move past. These locations are stated along with unacceptable locations in the instructions for every smoke alarm sold but far too often those instructions are ignored.

Current building regulations call for a smoke alarm in every sleeping area and also one immediately outside sleeping areas. Additional smoke alarms should be installed throughout a home but NOT in kitchens and probably not in close proximity to fireplaces. Each and every level of a multilevel house needs smoke alarms.

Ionization type alarms have a useful life of around ten years and should be replaced after that time.

Having smoke alarms is always going to be better than not having them. If you want even more protection than is offered by a smoke alarm you can bolster them with absolute and rate-of-rise temperature alarms. The ultimate is, of course, fire suppression sprinklers but the cost, especially to retrofit, is fairly steep. There are also many lifestyle changes that can seriously reduce the chance of fire in your home.
 
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Old 03-27-13, 09:11 PM
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My big question is--are they all the same (ion vs. ion, photocell vs. photocell)? All made in China, all at best 50% likely to alarm in a room full of smoke?

Many local fire departments give them away free. You think you're getting the best? Who even gives it a thought? My assumption that I'm sure is shared by most is that they're all "certified" to perform and extra $$ just gets you extra features. This doesn't look to be the reality of it though. How can the CPSC state that new alarms only operate half the time...and not force a recall or initiate some real performance testing? Maybe they're a little too preoccupied with recalling Barbie cars because some toddler might take it apart & chew on the battery
 
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Old 03-27-13, 09:31 PM
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Actually, the testing on them is to UL standards; which is NOT a government agency. It's run by the insurance underwriters who have to pay out if there is a fire liability claim, so they have a vested interest in reducing such exposures. UL testing is both extensive and expensive (which is why life safety products have such a slow development cycle).

That said, there is a wide range of qualities. The typical consumer grade ion smoke alarms are reasonably effective, as long as they are properly installed and _maintained_ and replaced when they reach their end of life (7-10 years)

With smoke alarms and detectors, there is a degree of "you get what you pay for". The $40 unit with photovoltaic detection is a very different animal from the 12-15 dollar ion smoke alarm that's the common builder's choice.

Remember, there is no 100% solution. Security and life safety is a balancing act between making the target better protected and not going so far that the cost/benefit ratio is too far out of whack...

My preference is good quality photo smoke detectors connected to an alarm system, even better, and far more reliable.
 
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Old 03-28-13, 07:35 AM
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My preference is good quality photo smoke detectors connected to an alarm system, even better, and far more reliable.
Better & more reliable how? Better parts...better design...or is it because they have to pass a different standard (UL268 vs. UL217)?
The UL must set the bar pretty low for so many to fail in a real fire.
 
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Old 03-28-13, 03:36 PM
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It's all about the criteria. The report you were reading was testing Ion smokes against a slow smolder fire, which is not the type of fire that they work best to detect. They are best for fast burning type fires. They get used so much because they are cheaper than the Photo smokes that are far better against the smoke and smolder fire, and because they were the first mass produced smoke detector technology; a fact that was pointed out in the article you cited...

I think that the building and code enforcement people _should_ make the photo smokes the default standard, but there are a lot of vested interests that are too "bottom line" obsessed to let that happen. In the real world, the slow smoky fire actually is the type that's most likely to happen in a residence.
 
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Old 03-28-13, 07:39 PM
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The 101 page NFPA report I cited was about all types of smoke alarms and there's a shocking number of failures of all types of sensors. But I'm sure most data--and probably most failures--are from the ion type since even today they continue to be the most popular. Thankfully they are fast losing ground to the photo detector type.


It's a little rattling when you learn that most "smoke alarms" don't go off in thick smoke and sense thin wispy burnt-toast smoke way better. But people don't die in toast fires
 
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Old 03-28-13, 08:56 PM
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guy48065, is there a purpose to this thread? If we can help you, or you can help us or someone else with the installation, testing, or troubleshooting of smoke detectors, that is good.

If your purpose is to spark a debate, that is not what these forums are for and you would be best served on some debate type forum.
 
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Old 03-28-13, 11:53 PM
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guy48605, maybe you should just build your house out of inflammable material.

This will allow you to put in any 'ol smoke detector to satisfy the codes and allow you to sleep at night.
 
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Old 03-29-13, 08:54 PM
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Not looking for a debate...looking for discussion and informed opinion. Isn't that what we do here?
 
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