Security, Access Control, and CCTV Systems
Core concepts
This domain covers intrusion detection (PIR, dual-technology, glass break, door and window contacts), access control (readers, controllers, electric strikes, maglocks, REX devices, fail-safe versus fail-secure), and video surveillance (camera types, lens and field of view, resolution, low-light performance, and recording retention). Understand supervised versus unsupervised zones, normally closed versus normally open contacts, and the role of the power supply and battery backup. Know that fail-safe locks release on power loss (life safety egress) while fail-secure locks remain locked, and that egress must never be compromised by access control.
Traps to expect
A classic trap is a fail-secure maglock on an egress door without a request-to-exit device and a listed release. Another is confusing a PIR's detection pattern with its range, or assuming higher camera resolution alone guarantees identification. Questions may test whether a door contact should be wired normally closed (supervised) versus normally open, and whether a reader provides entry control only or also exit tracking.
Worked example
Identify a face at 60 ft with a 1080p camera. Pixel density rule of thumb: identification needs about 80 px per foot of subject height, so a 6 ft person needs about 480 px vertically. A 1080p sensor has 1080 vertical pixels; at 60 ft, the vertical field of view must be about 13.5 ft. If the lens gives a wider view, identification is not achievable - move the camera or change the lens.