Security System Failures.....common

[docsleepy]

After many years of disuse, I recently went to work to get the alarm systems working. What I found was surprising.

Out of 23 alarm sensors on the first floor (we have a LOT of windows and a garage) 9 were failed. You could open the front door and several windows and no alarm at all.....so much for trusting alarm systems.

One door was not even wired. Nothing.

Turns out that the contacts within the tiny glass encased "reed switches" that are magnetically closed (and open when the magnet moves away) can sort of "spot weld" themselves in place, perhaps due to chronic current flow (galvanic deposition of metal?) or due to a surge of current due to induced flows of current from nearby lightning strike...according to what I read on the net. I found MANY reed switches that were "stuck". Most of them were made workable again by banging pretty hard on the plastic case with a metal tool. One broke (shattered) under that "repair" and had to be replaced, but many were salvaged.

I also learned that it is fairly easy for an astute criminal to get a very powerful magnet and stick it to your window near where the sensor is detected -- thus guaranteeing that the sensor will stay inactivated while he opens the window.....

We also have a motion alarm which would hopefully give us an additional line of defense, but my point is that it is very common for alarm systems that are not painstakingly checked, to fail. And thus you might very well have an intruder in the house without any alarm....

food for thought, and action.

 

[gym]

Well I have had alarm systems in 3 houses, in the last 30 years. If you have a system that is made within the last 20 years, it should signal you from the panel with an audible and led warning light. If not, you should replace the system. My old house had a system that was 20 years old, and still did that. It was so old that there was a no fee service contract on it. So check with the company who put it in, they will probably put in a new system for free or a very low cost just to keep you as a client.
PS: my best friend had one of the biggest alarm companies in NY and he would never lose a client over something like that, they make their money from the monthly EFT, so give them a call.
Also the sensors used now have their own batterys which last from 2-3 years depending on use. The new ones have either or both, the panels on my new one have 2 double A batterys and AC, the old one had 9v and DC,. So look into it and you may find that you can get a new system free.

 

[dmazur]

I used to install alarm systems -- many years ago.

Even then, the installer had the option of using NO logic instead of NC logic for a loop. The result was an increase in installation cost, as each sensor required a "home run" back to the panel, and a more complex panel.

However, as a result of having individual sensor circuits, you could generally "map out" a failed sensor and put the system back in operation. Better than no alarm. Effect repairs as soon as possible, but the first thing we did was get it back running, with the broken sensor disabled.

In order to use the magnetic reed switches on doors, we got NO switches that closed in the presence of a magnet, with an offset magnet that swept the sensor as the door was opened. (We knew about the external magnet trick.)

We also tested each account annually, tripping every sensor to make sure they weren't dead.

And the best installations had a "throwaway" system with a bell box that the bad guys could play with, with a completely independent silent alarm backing it up...

 

[docsleepy]

dmazur -- great ideas.
I could reconfigure for that type of switch on some or all of the switches. Never thought of that.

I'm a little "cheap" and so we gave up on the monitoring contract years ago. Not their fault for sensors that failed. Easily enough fixed. They wanted hundreds to come replace a busted keypad. They have to stay in business, but so do I: I found two keypads on the internet for 5% of what they wanted, got the rudimentary system going and now am working out the bugs.

(I was a EE by training)

In another thread people wondered why I would be concerned for an intruder if no alarm had gone off, and this is one reason.....these alarms need annual checking as you mentioned!

Thanks for all the info, all of you guys!

 

[Pyzon]

Good work, docsleepy-

You're already well on your way to sleeping better.

How are your locks (doors and windows) and the exterior lighting on the house ?

 

[P95loser]

I don't like the setup that dmazur just told you about the offset magnet. The reason for this is if the door is wide open, your security system will still arm and you could think you are secure and be armed with a door open.

 

[dmazur]

The reason for this is if the door is wide open, your security system will still arm and you could think you are secure and be armed with a door open.

Absolutely correct. The accounts we were servicing were industrial (commercial) and were not armed with someone still on the premises. It was far more important to make them resistant to external attack than to use the alarm as a check to see if the doors were shut.

Another example - Before the days of keypads, it was common to have a keyswitch near the "main entrance" to enable/disable the alarm. Most accounts preferred this to an entrance delay. However, if you used the switch as a "shunt" to disable an NC door contact (the easy way), the bad guys figured out how to defeat it by squirting it full of mercury. Our company used the switch to power an arming circuit, so all a mercury attack would do is permanently leave it armed.

Alarms are only one part of a "layered defense". Personally, I don't use them as a warning system when I'm at home. For that reason I have an abundance of motion detectors and very few door or window devices. Devices that are "always on" are the heat sensor near the furnace, and the flooding sensor.

Many individuals do arm their systems when at home, and many panels enable only the perimeter zone(s) when operating in this mode. For residential accounts it is undoubtedly more important to have that perimeter check than to have a magnet-attack resistant system. I should have mentioned that...

 

[docsleepy]

dmazur: thanks for even more insight. I have now fixed every busted sensor and wired the door that never got wired. Will continue to work on other security improveents, but this is a huge success so far.