What is the type of security (anti-theft) system called that sets off an alarm when the wire is cut?

Answer 1

You might be thinking of a "closed loop" sensor. This is a device that can be added to any car alarm and will set off the alarm if a connection is broken. Here's an example:
http://www.sonicelectronix.com/item_5366_Directed+502T.html

Another option: usually a car alarm sensor wire will trigger if the wire is grounded. So if you want the alarm to go off if a wire is cut, you can try bundling a sensor wire tightly with a grounded wire and wrapping the two wires with tape. If someone cuts the two wires together, the wire cutters will make a connection between the grounded wire and the sensor wire and set off the alarm.

Answer 2

Not always. That's why some people have theirs on a telephone line & it makes a direct call to their Security Company, who in turn, makes the call to the local authorities at the address that is on record with their phone number & property address. A false alarm can cost a person big bucks if their City has an ordinace & set fee. That's why a home or business with an alarm system must have a special license that is clearly posted in a conspicuous place & the local authorities can call the owner or authorized agent to shut off or disable the battery powered back-up that can ruin a neighbors day for 4-12 hours (depending on what type of battery they are using)! I once had a neighbor who had his hooked up to some type of a direct sytem & no one could figure out how to disable it. The Police wrote him a summons to appear for disturbing the peace & having an illegal & unregistered system. We later found out that he was cooking meth & that alarm was set off by fumes to alert those in the know. That's probably why the Police didn't want to go into his yard to begin with & they couldn't tell us about it! Not all alarms are for forced entry!...thought you'd like to know.

Answer 3

which wire? you can add a back up battery to an alarm (dei part# 520t) which will set off the alarm if the battery is disconnected or if the 12v wire is cut.

Answer 4

Yup, closed loop or supervised.