Power over Ethernet — PoE — is the quiet technology that transformed camera installation, and understanding what PoE is and why it matters will save you real money and real headaches. The idea is disarmingly simple: the same network cable that carries the camera's video also delivers its electrical power, so every camera needs exactly one Cat5e or Cat6 run and nothing else — no electrician per point, no power adapters dangling in junction boxes, no separate wiring plan. One switch or recorder becomes the power source for the whole system, which also means one UPS protects everything. This guide explains how it works, decodes the standards on the datasheets, and teaches the budget math whose absence causes the most mysterious failure in CCTV: cameras that drop only at night.
Key takeaways
- PoE sends safe low-voltage power and data down one network cable, up to 100 meters per run.
- Standards ladder: af for fixed cameras, at (PoE+) for PTZ and heavy IR, bt for the power-hungry giants.
- Standard PoE negotiates before powering — it cannot fry a non-PoE device; passive injectors can.
- Sum your cameras' maximum watts and keep it inside the switch's real budget — with night IR counted.
- Pure-copper cable is part of the power system — CCA cable steals voltage and causes ghost failures.
How PoE actually works
A PoE source — switch, recorder port, or injector — first performs a polite handshake: it probes the connected device with a tiny signal, asks whether it accepts power and how much it needs, and only then energizes the line at a safe low voltage around 48 volts. That negotiation is why standard PoE is safe by design: plug a laptop or an old printer into a PoE port and it simply receives data, never power. The camera side separates power from data internally, and everything happens over the same four pairs of an ordinary network cable. The practical limit to remember is distance: one hundred meters per segment, extendable by putting a switch or PoE extender in the path.
The standards, decoded
| Standard | Also called | Power at source | Feeds comfortably |
|---|---|---|---|
| 802.3af | PoE | Up to ~15.4W | Fixed cameras, intercoms |
| 802.3at | PoE+ | Up to ~30W | PTZ cameras, heavy IR, heaters |
| 802.3bt | PoE++ / hi-PoE | 60–90W | Large PTZ, illuminators, screens |
Reading a camera datasheet, match its consumption line to the ladder: a typical fixed camera draws four to seven watts in daylight and up to twelve with infrared blazing, which 802.3af covers; a motorized PTZ can pull twenty to sixty watts moving its motors and heaters, which is PoE+ or bt territory. The source must speak the standard the device needs — a PoE+ camera on a plain af port will either refuse to start or restart at night.
The budget math that prevents night dropouts
Every PoE switch has two ceilings: per-port power and total budget — and the total is almost always less than ports times per-port maximum. Eight cameras at twelve watts each need ninety-six watts, so an eight-port switch with a one-hundred-twenty-watt budget breathes, while one rated ninety looks fine at noon and collapses at dusk. That is the classic Egyptian support call: cameras perfect all day, then two or three of them rebooting in a loop after sunset — because infrared LEDs switched on across the site simultaneously and the total demand crossed the budget. Add your cameras' maximum watts, then buy at least twenty-five percent above the sum; the margin costs little and removes an entire category of mystery.
The mistakes we keep meeting
- Copper-clad aluminum (CCA) cable: cheaper per roll, it drops voltage over distance and starves far cameras — pure copper is part of the power system, not a luxury.
- Passive 24V injectors from the Wi-Fi world plugged into standard cameras — no negotiation, real damage risk; keep them away from CCTV.
- Counting ports instead of watts when adding cameras — the ninth camera fits the switch physically and breaks it electrically.
- Splicing network cable mid-run: every joint is a future corrosion point; run whole cables or add a proper switch.
- Forgetting the switch in the UPS plan — powering cameras from a protected recorder while the switch dies with the grid.
Frequently asked questions
Can PoE damage a laptop or a non-PoE device?
Standard PoE cannot — the handshake detects a non-PoE device and simply never sends power. The danger lives only in non-standard passive injectors that push voltage blindly; check labels before mixing gear.
How far can a PoE camera sit from the switch?
One hundred meters of cable per segment by standard. Need more? Place a small PoE switch or extender midway, or move to fiber with media converters for the long industrial runs.
Do all recorder ports supply PoE?
Only on PoE models — the recorders sold with built-in camera ports. A recorder's uplink network port never supplies power, and non-PoE recorders expect an external switch to feed the cameras.
Is PoE power expensive on the electricity bill?
A ten-camera system draws on the order of a large light bulb overall. The savings PoE brings in installation labor and copper dwarf anything on the monthly bill.
Related guides
- PoE switch selection guide
- Managed vs unmanaged PoE switches
- Network design for surveillance cameras
- Wired vs wireless cameras: which is more reliable
- What Is WDR in Security Cameras and Why It Matters
Get the power plan free with the camera plan
Every system FastEgy quotes comes with the PoE budget already calculated — cameras' night wattage, switch margin, UPS sizing. Send your site through the contact page and get the numbers before you buy, or browse switches and recorders in the FastEgy store.