Buying Guide · Camera Power
CCTV power supply guide.
A practical reference for powering commercial surveillance — PoE class sizing, 12 V local distribution, cable distance math, surge protection at every outdoor drop, battery backup runtime, and the outdoor power cabinet decision that separates a stable deployment from one that drops cameras every storm.
01 / PoE vs. 12 V
Two architectures. Pick by topology, not preference.
PoE puts power and data on the same Cat6 run from a central switch. Local 12 V (or 24 VAC for legacy) runs camera-side power from a wall transformer or distribution panel. Which fits depends on cable distances, camera count, and the network architecture:
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PoE (Class 3) Indoor 2MP cameras, short runs ≤ 13 W
PoE+ (Class 4) Outdoor IR, 4MP/4K, mid-load 13–25 W
PoE++ (Class 6) Multi-sensor, PTZ, large heaters 25–51 W
PoE++ (Class 8) Long-range IR PTZ, heated outdoor PTZ 51–71 W
12 V local Legacy retrofits, heaters, mixed brands 0–60 W per port
24 VAC Older PTZ / legacy installs Variable
Default to PoE for new installs — one cable per camera, fewer failure points, switch-side monitoring. Move to local 12 V when distances exceed PoE range, when the camera mix includes high-wattage devices that would blow the switch budget, or when the deployment is a retrofit on top of an existing analog or hybrid system. For the network-side sizing math, see the PoE switch sizing guide. For camera-side selection that drives the wattage budget, see the commercial security camera buying guide.
02 / PoE Budget Math
A 32-port switch is not a 32-camera switch.
The single most common camera-deployment failure: the switch port count covers the cameras, but the PoE budget doesn’t. A 32-port PoE+ switch with a 740 W budget can power 32 cameras only if each draws ≤ 23 W — and on a budget that’s already at 92% of nameplate, headroom is gone. The math:
- Sum nameplate camera draw — actual measured PoE draw from the camera datasheet, NOT class maximum. A Class 4 camera might draw 9 W typical, 25 W in IR + heater mode.
- Add IR / heater worst-case — IR LEDs cycle on at night, heaters cycle in winter. Both can double idle draw. Size to worst-case.
- Add 20% headroom — for cable loss, contact resistance, and camera firmware updates that can change draw silently.
- Stay under 80% of switch nameplate — modern switches throttle PoE delivery before they trip. Sustained operation above 80% shortens switch life and triggers thermal shutdowns in poorly ventilated cabinets.
- Plan one switch for cameras only — never share PoE budget between cameras and access points or VoIP phones. Camera draw spikes are unpredictable.
For installs where the camera mix pushes a single switch over budget, multi-switch designs are normal. Two 24-port PoE+ switches with 370 W each is a cleaner deployment than one 48-port at 740 W maxed-out.
03 / Local 12 V Distribution
Camera-side power that survives 10 °C below freezing.
For deployments where local 12 V wins — large camera count beyond switch budget, retrofits, heated PTZs, or sites with restrictive network closet space — the architecture is a centralized power distribution panel with per-camera fused outputs:
- Multi-output camera power — purpose-built distribution boards source 12 VDC or 24 VAC to 16–24 cameras from a single transformer + battery. Example: Altronix VertiLine24CD (24-output, 12 VDC / 24 VAC, individually fused).
- Per-port fusing — every output should be individually fused so a shorted run doesn’t take down the entire camera bank. PTC self-resetting fuses are common; replaceable fuses are preferred where lightning is a concern.
- Modular access power — for installs mixing cameras with access control on the same power chassis, modular systems like the LifeSafety Power FPO150 let you size and re-arrange outputs without re-wiring the chassis.
- Linear vs. switching — linear supplies (e.g. Altronix LPS5C) are quieter electrically but heavier and less efficient. For most camera installs, switching is fine; reserve linear for noise-sensitive integration (audio, intercom, alarm).
- Isolation transformer — for legacy 24 VAC cameras and any install where ground loops matter (audio paths, mixed brand integration), an isolation transformer like the ICC IS24VAC separates the camera power from upstream grid issues.
04 / Distance & Cable
100 m is a ceiling. 80 m is a budget.
Distance is where camera power deployments fail silently — the camera boots, streams in clear weather, then drops at full IR / heater load in winter. Practical limits:
──────────────────────── ────────────────── ──────────────────────────
Cat6 PoE / PoE+ up to 100 m Use 80 m as practical max
Cat6 PoE++ (Class 6/8) up to 100 m Heavier voltage drop; verify
Cat6 PoE extender chain up to 200 m One extender, ≤ 25 W class
Cat6 PoE → fiber converter limited by fiber 500 m+ on multimode
18 AWG 12 VDC at 4 W ~150 m one-way Voltage drop calc required
18 AWG 12 VDC at 12 W ~50 m one-way Heavier IR cameras need 16 AWG
16 AWG 24 VAC at 24 W ~150 m one-way Older PTZ pattern
For PoE runs beyond 100 m, the practical patterns:
- PoE extender — a small inline injector that re-powers and re-clocks the Cat6 mid-run. Example: Tripp Lite N785-IPOE-2 for gigabit PoE+ at extended distance. Limited to lower-wattage cameras; multi-sensor and PTZ usually exceed extender budget.
- Fiber media converter — for runs to outbuildings or perimeter cameras hundreds of metres out, convert to fiber at the switch and back to copper + local power at the camera. Cost is higher per drop but distance becomes a non-issue.
- Outdoor power cabinet — when fiber data goes out, source camera power locally from an outdoor PoE cabinet. Eliminates the long-PoE problem entirely.
For sites with cameras across multiple buildings, the multi-building fiber surveillance backbone architecture walks the full topology — fiber transport, local PoE injection, and per-building power.
05 / Surge & Grounding
Every outdoor drop needs a network surge.
Lightning rarely strikes a camera directly. It induces voltage into the cable, the voltage races back into the switch, and the switch dies — taking 16 other cameras with it. Surge protection is per-drop insurance:
- Network surge per outdoor camera — inline RJ45 surge protector at the network closet end of every outdoor Cat6 run. Example: APC ProtectNet PNET1GB — passes gigabit PoE+, clamps surge to the protective ground.
- Bonded to a real ground — surge protectors don’t work if the ground is the chassis of a switch in a plastic enclosure. Bond to building ground or driven rod.
- AC-side surge at the rack — the UPS line-level surge protects the rack power. A separate AC surge at the camera-side power supply protects the 120 VAC feeding the distribution board.
- Outdoor cabinet bonding — for cameras fed from an outdoor PoE cabinet, the cabinet itself needs a bonded ground stake. Ungrounded outdoor cabinets are antenna for induced surge.
- Camera-side network surge for high-exposure sites — for sites with frequent lightning or tall outdoor cameras, add a second network surge at the camera end. Cheap insurance for sites with documented outages.
06 / Battery Backup
Record-on-power-loss only works if the NVR stays alive.
A 30-minute outage that drops the NVR and switch is a 30-minute gap in evidence. Size battery backup to bridge the typical local outage plus margin. Three tiers:
- Small commercial — 30 to 60 min runtime — single rack UPS, line-interactive or online. Sized for typical 15–30 min utility events plus margin. Example: Eaton 9PX 1500VA (2U online UPS, double-conversion).
- Mid-sized commercial — 60 to 180 min runtime — larger UPS with external battery pack. Required for sites with documented multi-hour outages or critical 24/7 coverage. Example: APC Smart-UPS SRT 3000VA.
- Local camera-side backup — for cameras fed from a power distribution board, add SLA batteries on the chassis. Common pattern: a pair of Panasonic LC-X1242P 12 V 42 Ah SLA batteries gives hours of runtime on a 16-camera load.
Practical sizing: list every device that needs to stay alive (NVR, switch, distribution boards, network gear), sum their wattage, divide UPS Watt-hours by that sum for runtime. Half that result is realistic runtime under battery aging — replace SLA batteries every 3–5 years regardless of apparent state.
07 / Outdoor Power Cabinets
Power local. Run fiber back.
For cameras at the property edge — fence lines, gates, outbuildings, parking lots — the cleanest deployment is an outdoor enclosure that sources camera power locally and runs only fiber data back to the network closet. The pattern:
- Outdoor PoE cabinet — IP-rated enclosure with built-in PoE injector, AC input, optional battery. Example: Altronix NetWaySP1B — outdoor PoE+ with weatherproof seal and optional battery shelf.
- Industrial PoE switch for harsh environments — for sites with extreme temperature or vibration (mining, gate operators, exterior tower mounts), use industrial-grade hardware like the Antaira LMP-0801G-SFP — DIN rail, -40 °C to +75 °C operating range, redundant power input.
- Fiber back to core — single-mode or multimode fiber from the outdoor cabinet to the network closet. Distance becomes a non-issue; surge becomes much easier to contain because copper transit is short and bonded local.
- Local AC source — the outdoor cabinet needs an AC drop. If there isn’t one nearby, that’s a separate trade scope. Don’t promise the camera install until the AC path is confirmed.
08 / Common Failure Modes
What kills surveillance power deployments.
After commissioning 50+ commercial deployments, the recurring patterns:
- PoE budget oversold — switch nameplate is the marketing number. Actual sustained delivery is 80–90% of that. Plan to the sustained budget.
- Distance underestimated — measured Cat6 runs almost always exceed the original BOM. Walk the route before sizing.
- No surge on outdoor drops — every other camera install we audit lacks per-drop network surge. First lightning event takes down the switch.
- Battery left to age — SLA batteries dry out in 3–5 years. Sites we audit at year 7 are running on 20% of original capacity.
- Shared PoE budget with WAPs / phones — camera bursts collide with VoIP and WAP draw spikes. Camera switch should be camera-only.
- 12 V cable too thin — 18 AWG runs flagged as “fine on paper” voltage-drop into brownout under heater + IR load. Step up to 16 AWG for any long 12 V run.
- Ungrounded outdoor cabinets — cabinets bolted to a pole with no ground stake become a lightning antenna. Always bond.
For real-world examples that walk through camera power sizing on completed projects, see the 32-camera NDAA surveillance deployment and the commercial camera storage planning guide, which both reference PoE + storage in a single BOM.
Camera Power Review
Sizing power for a camera deployment?
Send the camera count by type, the network closet location, the outdoor camera locations, and the typical local outage duration. We come back with a switch sizing, distribution board picks, surge BOM, and a UPS runtime calc — before the order ships.