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Reliability of glass breakage listening devices

Discussion in 'Security Alarms' started by Andrew, Jan 4, 2006.

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  1. Andrew

    Andrew Guest

    The local consumer magazine in Washington DC says of glass breakage
    listening devices "A recent study by the Association of Central
    Monitoring Stations declared these devices unreliable".

    I can't find a date on the article, so I checked the web site of the
    Central Station Alarm Association. I couldn't find anything there
    either. I have had a few local companies come by to assess my home and
    almost all have recommended them.

    Are they reliable? Do they give lots of false alarms? Should I use
    them iin my home?


  2. I don't know how long ago that study was performed. Acoustic glass break
    detectors have never been 100% reliable. They can and do add to the
    security of an installation when properly installed though.

    Almost all of them will false if there's a heavy thunderstorm directly
    overhead. I used glass breaks (along with full perimeter magnetic contacts
    and interior motion detection)
    on most of my installations for many years with relatively few problems.
    That was in Connecticut. Now I live in Florida and I'd hesitate to use them
    here -- way too much lightning.

    Everyone has his own preferences on makes and models. I've had good results
    with IntelliSense (Honeywell) glass breaks. When they first came out
    Sentrol's (GE Security) Shatterbox series were awful. They would false if a
    broom dropped in a neighbor's house. :^) I haven't used these but several
    friends who use them indicate the more recent ShatterPro series seem to have
    overcome the early problems. I sell both brands to DIYers online and have
    not had any returns in quite some time.

    Best of luck.


    Robert L Bass

    Bass Home Electronics
    4883 Fallcrest Circle
    Sarasota · Florida · 34233
    941-866-1100 Sales & Tech Support
  3. Bob Worthy

    Bob Worthy Guest

    Glassbreak detectors are a device that need special attention both during
    the installation process and then again when/if there are any changes to the
    protected area. Changes in decor, furniture, window treatments, flooring,
    etc. will effect the sensitivity of the detector. What was good yesterday
    may not be good today after changes were made to the area. So after changes,
    the detector(s) will need to be checked for their sensitivity range. A
    detector that senses both frequency and vibration is recommended and one
    that has adjustable sensitivity capabilities is a must. Don't try to cover
    more area than what the detector is capable of at a mid range setting. There
    are range limitations and you should never take it out to the max. trying to
    save money. You won't be gaining anything except false alarms. The detector
    will be to sensitive, making it subject to false trips. Keep in mind that
    this device hears noise and feels vibrations, so location is important.
    There are simulating devices that the technician should be using when
    installing these devices to calibrate the sensitivity properly. Rattling
    keys or clapping hands is not the proper installation method. I have
    installed literally thousands of glassbreak detectors and have had good
    success with them. As with any power device, the panel battery can cause
    these devices to false if there is a black/brown out and the battery is not
    capable of supporting the power load on the system. Keep your battery
    reliable by changing every 3 years. To answer you question more directly,
    audios are fine and if installed and located properly should not be a false
    alarm problem. Hope this helps. Good luck.
  4. Bob La Londe

    Bob La Londe Guest

    I have had four breakins where the glassbreaks activated properly. None
    that I am aware of where they did not.

    Two were from vehicles that ran through the front of a building, and the
    other two were from a rock through the window.

    That being said I have also had some false alarm problems. Usually in small
    spaces with a high degree of echo. ie.. all tile bathrooms etc. Usually
    switching out the glass break to one with adjustable sensitivity will reduce
    this problem.

    I have had two odd circumstances that caused false alarms. One was a small
    barking dog. If it barked in one particular room of the house it would
    trigger the glassbreak in that room. It did not trigger the glass break in
    any other room. There was a very bad acoustic echoe in the room in
    question. The other odd one was in a store front. A slightly over
    sensitive glass break tripped when ever somebody knocked on the front glass.
    Not a sound volume or combination that would normally trigger the
    glassbreak. As it turns out they had a toy bird in a cage that chirped
    whenever there was a loud noise in the area. A loud smack on the glass
    would alert the glassbreak sensor and then the bird chirpig what trip it. I
    stood there on ladder staring at it until I found the cause.

    One thing to consider is that there are some circumstances where a
    glassbreak may not operate when there is a broken window. One example is
    where they are installed and tested at near maximum range in a room where
    there are no or very light curtains, then later heavy drapes are installed.
    They also typically do not work reliably with small panes of glass.

    In your home if you do not skimp on them they should work reliably with few
    to no false alarms. If you do not have them active when the house is
    occupied there should be no false alarms, but quite often people prefer the
    level of detection they get by having their glassbreaks active when they are
    at home. If you do simpley discipline yourself to call in any false alrms
    to your central station right away and know how to silence your alarm when
    it goes off.
  5. alarman

    alarman Guest

    I have this image of you standing on a ladder, staring unblinking at the
    errant device, one eyebrow cocked, until the glassbreak.....blinks.
  6. Bob La Londe

    Bob La Londe Guest

    Snerk. Ya pretty much right on the money there.
  7. J Barnes

    J Barnes Guest

    On the subject of glass breaks, I had one do its job last night. :) It was
    an intellisense fg series. Ive also had them not do their job when they
    should have :( But thats why I back them up with motions

  8. Frank Olson

    Frank Olson Guest

  9. I have had very good luck with the Caddx 2000. They are round so we always
    get them mounted right. There are no adjustments and false alarms are rare.
    For years I used Visonic GFD20. They were good for their day, but their
    rheostat gets dirty and has to be excercised to maintain the sensitivity you
    set. Problem is when they get dirty, the unit loses sensitivity and
    eventally is useless.

  10. Bob Worthy

    Bob Worthy Guest


  11. Frank Olson

    Frank Olson Guest

    Thanks Allan... I'll have a look at 'em.
  12. Chub

    Chub Guest

    I like those also. the rectangular one fits in a single gang box. GE
    Solution 2000 now.
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