In the field of industrial security systems, the methodology of protection is quite different. First is to detect, second to delay, and third to alarm. Industrial alarm systems are designed as an integration of several sensor systems. The most important for big facilities would be the outer fence on which a sensor is placed. It would detect and delay the intruders before they even reach the building itself. As described below, there are a number of different fence mounted sensors, each with its own pros and cons. Other than the fence mounted sensors, there are also buried perimeter sensors that can be put on top of a wall or buried underground to create a hidden defense line. This only allows the security system to detect an intruder, but does not delay them. Another choice for detecting is Closed Circuit Television (CCTV). A guard can watch the screens or video motion detection software act the part. In any case CCTV is ineffective as a standalone sensor because it’s affected by weather conditions as cameras cannot see in heavy fog, rain and snow. The last line of protection is the building itself. It can be protected by infrared sensors, microwave sensors, smart locks and magnetic door sensors.