Closed-circuit television (CCTV) systems are essential in modern building services management. Common packages include cameras, lenses, cables, and recording and monitoring equipment. Electrical contractors, facilities providers and building managers all need to know the basics of these devices in order to specify and select the best products that form a system of professional standards.

Monochrome cameras are superior in low-light conditions and can be matched to infrared (IR) illumination, while colour cameras are best for identifying and tracking targets. Advanced systems, such as pan, tilt and zoon (PTZ) cameras and IR colour/mono cameras, are capable of tracking and identifying moving targets in a wide range of light conditions. Different cameras require specific types of cables and wiring, as recommended by their manufacturers.

Meanwhile, fixed-focus lenses are used when the field of view is not going to be adjusted, while vari-focal lenses allow the scene in view to be altered during installation. Even better, zoom lenses and motorised zoom lenses enable their operators to magnify and change the field of view at ease.

Furthermore, recording and monitoring equipment allow access to and storage of video images, using a great variety of devices such as digital video recorders (DVRs), monitors, PCs, CDs, DVDs and even the Internet. Special techniques such as telemetry and video motion detection (VMD) analyse the video images and operate the cameras accordingly, including automatic start/stop, pan, tilt, zoom and wash/wipe functions.

Finally and most importantly, there should be sufficient lights on site to illuminate the camera’s field of view.