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Video Cameras
(Chapter 2   Video Surveillance, Continued)

Placement and mounting

To avoid the effects of blooming, streaking, and glare, all of which can wash out the video image, exterior cameras should be mounted below the nighttime lighting sources and aimed downward to shun direct sunlight, especially that occurring during sunrise and sunset. This may require a minimum mounting height of 18-20 feet. An even higher mounting height will help prevent vandalism of the camera. Consider the height required if a truck can be parked directly beneath the camera, where a perpetrator could stand on the truck's cab to reach the camera. Cameras should always be mounted on solid surfaces to prevent wind movement and vibration. Wooden poles can twist with high winds over a period of time and cause the camera view to change. Under these conditions, the camera may periodically require direction alignment.

In the interior environment, cameras cannot be mounted higher than the ceiling so it may be easier for an intruder out-of-view of the cameras to vandalize or tamper with them. This situation can be helped if the scene viewed by two cameras includes the other camera, such as cameras mounted at each end of a hallway or room and aimed to include a view of the other.

Cabling to the cameras must be protected from vandalism and tampering. In interior installations, wires can be hidden from view and therefore protected by routing them through the ceiling and/or walls. However, the small amount of wiring that may run from the camera to the wall or ceiling must be in a conduit. Also be aware that employees with access to the ceiling could tamper with your camera wiring.

For exterior camera installations, the video and power cabling to the cameras should be installed in a conduit. For underground runs, special cabling for direct burial should be used if the cable is not installed in a conduit. The cable running up poles or buildings to the cameras must be in a conduit because this is a very vulnerable location for vandalism and tampering.

Camera mounts should be selected to handle the weight of the camera, lens, and housing. A good rule of thumb is to select a mount that will handle twice the weight of the load as calculated from the specification sheets of the selected components. Mounts are usually specified as indoor or outdoor mounts. A mount designated for installation outside also can be used for interior installations, but an indoor mount should not be used outdoors. Outdoor mounts are treated for corrosive effects not normally encountered indoors (although one common exception would be in a high-humidity area such as an indoor pool). Some mounts have separate mounting bases and must be selected for either suspended ceiling or solid wall/ceiling mounting locations. Pole mount brackets are available for some outdoor camera mounts. The mounts should have adjustable heads to allow for up/down and sideways adjustment of the camera field of view. Mounts also come in different lengths, and this may be a consideration when a camera housing adds to the length requirement. Primarily, the mount should be rigid enough and mounted securely enough to the surface so that the camera does not vibrate under normal operating conditions.

Many camera manufacturers and distributors also carry a full line of camera mounts, as well as housings for their cameras. Mounts are priced anywhere from approximately $30 to $150.

 



Research Report:   The Appropriate and Effective Use of Security Technologies in U.S. Schools