Closed Circuit Wiring

This is one of the simplest types of detection devices there is in alarm systems and, in essence, is an extension of the detection loops. It is used to detect forced entry through solid structures such as doors, walls, ceilings, etc.

Closed circuit wiring, (sometimes referred to as “lace wiring”), is in fact a single strand of fine insulated wire that is stapled on to the structure, to be protected in a pattern similar to the one seen below. This then forms part of the detection circuit and when broken will activate the system.

Below we see a door which is protected by the use of lace wire. Here we have both a detection and a tamper loop. The wire is connected to the alarm cable by means of a junction box. (A more detailed drawing of this can be seen on the next page). Any attempt to break through the door will result in breaking the wire and hence activate the system.

Because this wire is easily damaged it is necessary to protect it by covering the door with a sheet of hard board, the same would apply to any other structure.

Diagram of connection to alarm cable using junction boxes and a door loop
(for more information on this see section entitled “hardware and wiring”)

Diagram showing hardboard tacked over lace wiring to protect it from damage.