PoE Power Budget for Factory Cameras in India: Sizing It Right
To size a PoE budget, add every camera's peak wattage, keep each camera under its port's IEEE class cap and the total under the switch's PoE power budget, then leave 20-30% headroom. In India, the harder job is surviving load-shedding: put the switch and NVR on a UPS fed from a generator-backed line, or the cameras go dark during the cut you cared about.
In short:
- Budget cameras at peak draw (IR/heater on), not the datasheet idle figure.
- Two caps must both hold: per-port class cap and total switch PoE budget.
- Leave 20-30% headroom for cable loss, simultaneous IR spikes, and boot inrush.
- Put switch and NVR on a UPS — the switch powers the cameras, so an NVR-only UPS still goes blind.
- In India, use an online (double-conversion) UPS: the source it falls back to is a wobbling diesel generator, not clean grid.
What actually kills factory CCTV in India: a real outage
Most guides stop at watt-math and tell you to "put it all on a UPS." Here is what a real power cut did to a live camera install.
Table: Mihnovka pilot, grid cut 2026-07-13, 11:08:14 to 12:57:54 (~110 minutes; Kernel-Power 105 log).
| Component | Backup | What happened at 11:08 |
|---|---|---|
| Server laptop (i7-8565U) | Internal battery | Rode the full 110 min. Uptime stayed at 16 days — no reboot |
| PoE switch (TP-Link TL-SG1005P, unmanaged) | None | Died instantly |
| Landlord router / uplink | None | Died — Tailscale went offline |
| 3 cameras (PoE) | None (switch-powered) | All went dark |
| Recording (3× ffmpeg) | — | All three aborted at 11:08:19, error 0x8007042B |
Everything came back on its own at 12:58. Two lessons the SERP does not tell you. First, "no reboot" hides a total blackout: the laptop's battery masked the event, so a naive uptime check would have reported the plant healthy through nearly two hours of zero camera coverage. Second, the switch is the single point of failure — one unbacked 5-port box took down all three cameras and the recording at once. Over 14 days we logged exactly one cut, in daytime, none at night. The fix in flight is a UPS on the switch and router — the cheap box that carries the whole camera plane.
Key numbers (planning maxima; confirm per model)
- PoE cable limit: ~100 m per Cat5e/Cat6 run for data and power (IEEE 802.3).
- 802.3af (PoE): ~15.4 W at source, ~12.95 W delivered at the camera.
- 802.3at (PoE+): ~30 W at source, ~25.5 W delivered (25 W guaranteed minimum at the device).
- 802.3bt Type 3 (PoE++): ~60 W at source, ~51 W delivered.
- 802.3bt Type 4 (PoE++): ~90 W at source, ~71.3 W delivered.
- Cable loss: a 100 m copper Cat6 run loses roughly 5-10% of source wattage as heat.
- Recommended headroom: 20-30% over summed peak draw.
How much power does a factory camera draw?
Vendor datasheets vary, so confirm against each model's spec sheet — that caveat holds for every figure below.
- Fixed dome / bullet, IR on: ~4-12 W. Fine on 802.3af for many models; IR-heavy night draw pushes some to PoE+.
- PTZ (pan-tilt-zoom): more — motors and long-range IR often need 802.3at or 802.3bt.
- IR illuminators and housing heaters: the trap. A camera that idles at 5 W in daytime spikes well past that when IR floods on at dusk or a heater cycles. Budget every camera at its worst-case draw, or the switch hits its cap exactly when you need night vision most.
PoE vs PoE+ vs PoE++: IEEE 802.3 classes and watts
PoE is standardised by IEEE 802.3. The switch (PSE) sources more watts than the camera (PD) receives, because cable resistance eats the difference — 5-10% over a 100 m Cat6 run, more on thin cable. Plan against delivered watts.
Table: IEEE PoE classes and watts delivered at the camera (planning maxima).
| Standard | Common name | At source | Delivered at device | Typical use |
|---|---|---|---|---|
| 802.3af | PoE | ~15.4 W | ~12.95 W | Fixed dome/bullet, no heater |
| 802.3at | PoE+ | ~30 W | ~25.5 W | IR bullets, small PTZ, mild heaters |
| 802.3bt Type 3 | PoE++ | ~60 W | ~51 W | Large PTZ, multi-sensor |
| 802.3bt Type 4 | PoE++ | ~90 W | ~71.3 W | Heated PTZ, illuminator-heavy |
"PoE+" and "PoE++" are marketing shorthand for 802.3at and 802.3bt — buy to the IEEE number. Two mechanics drive the gap: a camera advertises its class in a detection handshake and the switch reserves that budget whether the camera draws it or not (so an over-classed camera wastes budget), and conductor gauge matters — 23 AWG copper Cat6 loses less over 100 m than thin 24 AWG.
How to calculate total PoE switch budget
Two caps must both hold:
- Per-port cap — no port exceeds the class it supports (a 30 W PoE+ port cannot feed a 60 W PTZ).
- Total switch power budget — the "PoE power budget" on the spec sheet, usually less than all ports at maximum. An 8-port switch rated 30 W/port does not necessarily deliver 240 W.
Sum of each camera's peak draw + 20-30% headroom ≤ switch total PoE budget, and every camera's peak ≤ its port's class cap.
One number the watt-sum misses: boot inrush. When the grid returns and every camera and IR illuminator cold-boots at the same instant, the momentary draw runs above steady peak. Size the switch and UPS for that simultaneous cold start, not the calm running total — a switch loaded to the brim can trip into a boot-loop the moment power comes back.
Worked example: 8-camera shed
Table: worked PoE budget for a typical 8-camera factory shed (~115 W after headroom).
| Camera | Role | Class | Peak draw |
|---|---|---|---|
| 1-4 | Fixed bullets, aisles, IR | 802.3af | 10 W each = 40 W |
| 5-6 | Fixed domes, work cells | 802.3af | 8 W each = 16 W |
| 7 | Gate PTZ, long-range IR | 802.3at | 25 W |
| 8 | Dispatch dock bullet, IR | 802.3af | 11 W |
| Subtotal | 92 W | ||
| +25% headroom | ~115 W |
Buy a switch with a ~120 W or more total PoE budget and at least one PoE+ port for the PTZ. For continuity, that switch plus the NVR is roughly a 150-200 W load once you add their own electronics — an indicative ~600-1000 VA online UPS carries it through the generator changeover with a few minutes of runtime. Buy the next size up if you plan to add cameras; check how many cameras a factory floor needs before you fix the count.
Do PoE cameras keep working during load-shedding in India?
Only if you power for the failure, not just the cut. Everyone tells you to put the chain on a UPS. That is table stakes. The three things that actually decide whether cameras survive in an Indian plant:
The generator changeover is dirty. When the grid drops, a diesel genset takes seconds to catch and its output wobbles on cold start — unstable voltage and frequency. A cheap line-interactive UPS may fail to sync to that wobble and drop the load anyway. Because CCTV falls back onto a generator rather than clean grid, spec an online double-conversion UPS, which rebuilds the waveform and rides the transfer without a gap.
Surge and earthing, not runtime, is the real camera-killer. A PoE surge — monsoon lightning on a long yard run — travels the Ethernet cable back into the switch and can take out every port at once, the exact single point of failure the watt-math ignores. Indian plant earthing is often poor (>5 ohm), which makes surge protectors useless. Spec a dedicated ground rod under 5 ohm and a per-run PoE surge protector on any outdoor gate, yard, or perimeter camera.
An office switch dies on a factory floor. "Factory" is the operative word: VFDs and large motors inject EMI and micro-surges onto the same power that feeds the switch, and dust, vibration and heat finish off consumer gear. Use a DIN-rail industrial switch — fanless (dust), metal IP40, vibration- and wide-temp-rated, ideally with dual DC feed.
Buy managed, for one specific reason. On an unmanaged switch — like the TL-SG1005P that died in our pilot — a budget pinch silently drops the lowest-priority ports with no alarm. A managed switch lets you set PoE port priority, so under strain the non-critical aisle cameras drop first and the gate, exit and safety cameras stay powered by design. Add a PoE watchdog to auto power-cycle a camera that hangs after the generator stabilises. That turns an unmanaged bug into an engineered outcome.
One more India-specific field failure: CCA (copper-clad-aluminium) cable, rampant in the Indian market and sold as "Cat6." Its resistance is far higher than pure copper, so it both starves PoE at distance and overheats. Specify pure-copper Cat6 explicitly and check it on delivery.
That blind window during a cut is exactly where a service like Mama — which watches the floor through the cameras and messages you what is running, idle, or unsafe — loses its eyes. It can only flag an idle press or an open guard while the cameras stream, and load-shedding blindness tends to land at night, when a walk of the floor is hardest. Which is why the power chain matters more than the cleverness watching over it. For scale, even a full 3-shift manned guard post in India — around four to four-and-a-half guards with relief and statutory PF/ESI/bonus loaded — runs an indicative ₹75,000-1,10,000/month (armed or metro postings sit at the top), and still cannot watch every zone at once.
Where this sits in the bigger decision
PoE budgeting is one line item. Storage (NVR vs cloud) carries its own continuity implications — see NVR vs cloud video storage in India — and the full build cost, switches and UPS included, is in what a factory camera AI system costs in India.
Two honest limits: watt figures above are planning maxima, so size against the exact camera and switch spec sheets, and PoE budgeting cannot fix an undersized generator or a UPS with dead batteries. The watt arithmetic is the easy half; power continuity is where these installs actually fail.
FAQ
How many watts does a factory CCTV camera draw?
A fixed dome or bullet with IR draws roughly 4-12 W, comfortably inside 802.3af. PTZ cameras with motors and long-range IR draw more and often need PoE+ (802.3at, ~25 W) or PoE++. Always budget the peak with IR and heater on, not the daytime idle figure.
Does a PoE switch power cameras during a power cut?
Only if the switch itself has backup. PoE cameras draw all their power from the switch, so if the switch loses mains the cameras go dark instantly — even if the NVR is on a UPS. In our pilot, an unbacked switch took down all three cameras the moment the grid dropped. Put the switch on a UPS.
What size UPS do I need for PoE cameras?
Size for the switch's real PoE load plus the NVR and their electronics — typically 150-200 W for an 8-camera shed. That points to an indicative ~600-1000 VA online (double-conversion) UPS, fed from a generator-backed circuit for cuts longer than a few minutes. Online, not line-interactive, because it falls back to a generator.
What is the difference between PoE, PoE+ and PoE++?
They are IEEE 802.3 standards: PoE (802.3af) delivers ~12.95 W at the device, PoE+ (802.3at) ~25.5 W, and PoE++ (802.3bt) up to ~51 W (Type 3) or ~71.3 W (Type 4). "PoE+/++" are marketing names — match the camera's requirement to the IEEE class.
How far can a PoE camera run from the switch?
About 100 m per Cat5e/Cat6 run for both data and power, per IEEE 802.3. Beyond that, use a PoE extender, a fibre media converter, or a local switch. Use pure-copper cable — copper-clad-aluminium "Cat6" starves PoE and overheats at distance.
Quick checklist
- Confirm each camera's peak draw (IR/heater on), not idle.
- Match every port to the right IEEE class (af / at / bt).
- Keep total load ≤ switch PoE budget, with 20-30% headroom, sized for boot inrush.
- Keep runs under ~100 m on pure-copper Cat6; extend with fibre beyond that.
- Switch and NVR on an online UPS, fed from a DG-backed circuit.
- Ground rod under 5 ohm; per-run surge protectors on outdoor cameras.
- Buy managed: set PoE priority so gate and safety cameras drop last.
- Test it: cut the grid and confirm every camera stays up.
Standards reference: IEEE 802.3 Ethernet is the authoritative source for PoE power classes (af/at in Clause 33; Type 3/4 in the 802.3bt amendment).