Edited by FerFAL to add:



Thanks Don for the interesting comment.



In my experience motion sensors, (WELL placed and distributed), with a properly programmed alarm are a combination pretty much impossible to defeat.

As always machines hardly fails, human error is the most common cause.

What you need to do is make sure that the main panel is also covered by motion sensors.



The most common problems in my experience are:



1)Going cheap on the motion sensors.

Buying ones of low quality is a common mistake. Also wanting to save money and not covering a certain area. That area will be picked clean. Robbers somehow end up knowing what’s protected and what’s not.



2)Improperly placed sensors.



3)Sensors set to a very low level of sensitivity, or too far away. Usually the real effective range they have is just ½ of what the manufacturer swears by.



4) Also telling employees about the password. Very common mistake. Leaks like these end up in robberies.



5) Another common one is thinking robbers will just run away as soon as the alarm goes off. Many times they do nothing, that’s why the alarm should call you and the cops.



6) Occasionally they cut the phone lines and this is pretty effective and smart. But you can prevent this by having it connected to a hidden cell phone.



7) They sometimes brake or disable the siren or bell. Preferably you’ll have two, at least one of them well hidden.



As you say, it should not be a reason to stop being alert, but I find it to be a good layer of security, specially for when you are not home.



Dog post coming up soon :)



FerFAL

Don Williams said...1) I don't like security systems -- they and security companies lure you into dropping your guard by giving you the ILLUSION of security. In reality, there are ways to bypass many of them. An unpleasant surprise when you get home.2) I don't want to discuss details on the internet, but magnetic contact switches, for example, can be detected with a stud finder or compass and compromised with a strong magnet (holds switch closed while door with security magnet is opened.) There are special contact switches made which can't be compromised in this matter. They have an internal switch on a seesaw balance beam which will close an alarm switch if subjected to any magnetic field other than the one for which they are precisely calibrated.3) Any security system is rigid -- not intelligent and not adaptive -- and hence vulnerable to attack. I'm not saying to not get one -- they are better than nothing -- but don't think they are infallible and try to learn something about their shortcoming so that you can distinguish between a good security company and one that's just taking your money.4) Plus, if you get a security system, be sure that each sensor has a resistor where it connects to the two wires leading to the alarm box --so that someone can't simply bridge the two wires with a short (allowing a sensor to go off without the alarm box recognizing it.) Also, don't use the security system's standard resistor --thieves can find out what it is and use one to short the connecting wires. Rather, split the resistence up into two resistors -- put one resistor at where the two wires connect to the alarm box and put the other resistor at where the sensor connects to the two wires.5) A good dog --trained to NOT accept food from strangers -- is better if kept behind closed doors. In difficult times, of course, it can be tough finding food for the dog-- although a good little lapdog like Paris Hilton's chilahua is just as good as a Rottweiler when sounding an alarm.A dog and security system together give multiple layers of detection -- but the security system has to allow you to turn off interior motion sensors in areas where the dog is roaming at night.6) Another thing to be aware of is that lots of lockpicking info is available on the internet. There are some locks made (Medeco, Abloy, etc ) which are essentially impossible to pick. Ever the average lock can be made much harder to pick by having the locksmith install special pins.7) Finally, look at the ENTIRE perimeter around your house. Our cheap stick frame houses in the USA have walls which can be cut through with an axe no matter how strong your front door is. Sliding deck doors can be lifted up out of their frames. And some thieves come in through the ROOF /Attic --which bypasses first floor alarms.A number of security companies do the business equivalent of selling a condom with a hole in it. May be a small hole -- may work some of the time. But when it fails -- uh oh.And some companies do the equivalent of selling a condom with SEVERAL holes in it.