Security, Access Control, and CCTV Systems
What this domain tests
Security, Access Control, and CCTV Systems tests whether you can apply power, locking, and network fundamentals to real installations. Expect fail-safe versus fail-secure hardware, request-to-exit devices, power supplies, PoE budgets, camera resolution, and video storage calculations.
Core rules
- Fail-safe locks unlock on power loss and are used where life safety requires free egress. Fail-secure locks remain locked on power loss and are not a substitute for a code-compliant exit.
- A request-to-exit device is required where the door hardware does not provide free egress. It must release the lock reliably.
- Access-control power supplies need battery backup and voltage-drop checks. Lock current can be high and continuous; use the correct gauge and a supply with adequate reserve.
- PoE has a budget. A switch rated for 240 W total may not power every port at the maximum class. Check per-port and total budgets, cable length, and camera draw.
- Camera storage is a bit-rate calculation. Resolution alone does not determine storage; codec, frame rate, scene complexity, and retention days matter.
- CCTV lenses and sensors have lux and dynamic-range limits. A camera that works in a lit lobby may fail in a dark parking lot.
Worked example
Four cameras record at 4 Mbps each, 24 hours per day, for 30 days. Each camera uses 4 Mbps ÷ 8 = 0.5 MB/s. Per day, 0.5 × 86,400 = 43,200 MB, or about 43.2 GB. Four cameras use 172.8 GB per day. Over 30 days, that is 5,184 GB, or about 5.18 TB. Add 20 percent overhead for indexing and variance, giving about 6.2 TB. Select a usable RAID capacity above that figure, not the raw drive label.
Traps
- Using fail-secure locks on a path that needs free egress.
- Forgetting the REX device or miswiring it.
- Counting PoE ports but not the total wattage budget.
- Estimating storage from camera count only.
- Ignoring voltage drop on long lock or camera runs.