high security burglar alarm sensor

Low-cost domestic burglar alarms often operate on the loop principle. A number of normally closed microswitches protect points of entry. These are all connected in series, so that opening a door or window will open one of the switches and break the circuit, thus setting off the alarm. Similarly any attempt to cut the wires leading to the switches will set off the alarm. However, this type of circuit is not proof against bridging out a switch with a link, which can easily be done if the wires are not concealed. Concealment of the wires increases the difficulty of installing an alarm, and a surface run of twin core bell flex is a much more attractive pro-position to the home constructor.