Physical Security Systems and Access Control
What this domain covers
Physical Security Systems and Access Control tests intrusion detection devices, door hardware and access control architecture, camera imaging performance, and the life-safety rules that override convenience. Questions frequently combine a device with a code requirement, such as a magnetic lock on an egress door.
Core rules
- Detectors: PIR responds to changes in infrared energy; dual-technology units require both PIR and microwave, which reduces false alarms. Glassbreak detectors listen for an acoustic signature and are not substitutes for door contacts.
- Access control chain: credential, reader, controller, power supply, lock, request-to-exit (REX), and door position switch (DPS). The DPS reports door status; the REX releases the lock for egress.
- Fail-safe locks unlock on power loss (maglocks); fail-secure locks remain locked on power loss (electric strikes). Egress doors normally require fail-safe release.
- NFPA 101 permits access-controlled egress doors only with listed hardware, an egress-side sensor, a manual release within 5 ft of the door at 40 to 48 in, loss-of-power release, and fire alarm release. Delayed egress uses a 15-second delay with immediate release on fire alarm and requires signage and AHJ approval.
- ADA: interior hinged doors should open with no more than 5 lbf; exterior hinged doors no more than 8.5 lbf, except where fire-door closing forces govern.
- Camera performance is judged by pixels per foot at the target, not megapixels alone. Commonly applied thresholds are about 20 ppf to detect, 40 ppf to recognize, and 80 ppf to identify.
Worked example
A 1920-pixel-wide camera watches a 30 ft gate. Pixel density is 1920 ÷ 30 = 64 ppf. That supports recognition of a person but not positive identification of a face. To reach 80 ppf the scene width must be no more than 24 ft, so the designer can narrow the lens, reposition the camera, or use a 2560-pixel camera, which yields about 85 ppf at 30 ft.
Traps that cost marks
Installing a maglock without a REX, manual release, or fire alarm release; reversing fail-safe and fail-secure; assuming a higher-megapixel camera guarantees identification; and forgetting that a DPS is not a REX. Also watch questions that apply ADA force limits to fire doors without checking the door hardware standard that governs closing force.