PoE, PoE+, and PoE++: Powering Your Security Cameras the Right Way

Power over Ethernet (PoE) is one of the quiet conveniences that makes modern IP surveillance practical. A single network cable carries both data and power to each camera — no separate electrician, no power outlet at every mounting point. But not all PoE is equal, and undersizing power is one of the most common reasons a camera reboots randomly, drops offline in cold weather, or never works properly from day one.

The three PoE standards

PoE is governed by IEEE standards. Each generation delivers more power than the last:

The difference between “power at the source” and “power at the device” matters: some power is lost as heat over the cable run. The longer the cable, the more is lost — which is why a camera that works fine on a short cable can misbehave at the end of a 90-metre run.

How much power does your camera need?

Power draw depends heavily on what the camera is doing:

• Fixed cameras : a basic fixed dome or bullet camera typically runs comfortably on standard PoE.
• Cameras with infrared illumination : IR LEDs draw significant power, especially at night when they switch on. A camera that idles within PoE limits during the day can exceed them after dark.
• Heaters and blowers : outdoor cameras in cold climates have built-in heaters. These draw their highest power on the coldest mornings, exactly when you can least afford the camera to fail. Cold-weather cameras usually require PoE+ or higher.
• PTZ cameras : the motors that pan, tilt, and zoom draw substantial power. Most PTZ cameras require PoE+ at minimum, and many require PoE++.
• Cameras with edge AI, audio, or attached devices : analytics processors, speakers, and powered accessories all add to the budget.

Always size to the camera’s maximum rated power draw, not its typical draw. The camera will hit that maximum at the worst possible moment.

The most common PoE mistakes

Trusting the switch’s total budget. A switch rated for, say, 120 W total cannot necessarily deliver 30 W to every one of its ports at once. Check both the per-port rating and the total power budget. A fully loaded switch of high-draw cameras can exceed the total even if each port is within spec.

Ignoring cable distance. PoE is rated to 100 metres of cable. Push past that and voltage drop will cause intermittent failures. Beyond 100 m you need a PoE extender, a fibre link, or a switch closer to the cameras.

Using poor or partial cable. Copper-clad aluminium cable, or thin-gauge cable, has higher resistance and loses more power. Use solid-copper, properly rated Ethernet cable for any PoE run.

Forgetting cold-weather peaks. A system commissioned in summer can fail its first hard winter when every camera heater fires at once. Size the power budget for the worst-case season.

Switches vs midspans

There are two ways to deliver PoE. A PoE switch combines network switching and power injection in one device, the cleanest option for new installations. A midspan (or PoE injector) adds power to the line between a non-PoE switch and the camera, useful when you’re keeping existing network switches or need to boost power on a specific run. Both work; for new builds, a properly sized PoE switch is usually simpler.

Plan power as carefully as you plan coverage

It’s tempting to treat power as an afterthought once the camera positions are decided. Don’t. Total up the maximum draw of every camera, confirm your switch’s per-port and total budget covers it with headroom, verify cable runs stay within 100 metres, and account for the coldest day of the year.

If you’d like help sizing PoE switches and midspans for your camera fleet, our team can build the power budget alongside the camera plan. Request a free quote and we’ll make sure every camera has the power it needs.