PolyPhaser: Security Cameras, CATV, GPS and Satellite Protection
Security Cameras, CATV, GPS and Satellite Protection
Outdoor Closed Circuit Television (CCTV) Security Cameras can be a prime target for lightning. They are usually mounted on a building or other vantage point such as a metal o r wood pole. A lightning strike can not only destroy the camera, but can damage your control console due to energy flowing back through the coax and camera power wiring.
When lightning strikes a tower or other large structure, there is a high peak voltage at the strike point flowing outward and downward through any path it can find to earth ground. A support pole develops a high L di/dt peak voltage drop along its length to earth ground. A large steel reinforced structure can conduct the energy to earth ground through its steel reinforced concrete footers and electrical ground system. A camera mounted and grounded to a building with steel reinforced construction will usually have less inductance to ground than a camera mounted on a self-supported tower or pole. Less inductance to earth ground means less peak voltage at the camera.
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