What is a PoE camera: how power over ethernet works
Ethernet cable contains four twisted pairs. Power over Ethernet sends DC power along those pairs alongside the data, so one cable does both jobs. A PoE switch or injector supplies the power; the camera draws what it needs.
Standards-compliant active PoE detects a compatible device before supplying power. Passive PoE requires separate compatibility checks; do not assume every port uses active negotiation. Standards define the power budget: 802.3af provides up to about 15 W per port, 802.3at (PoE+) about 30 W, and 802.3bt more again. Check each camera's required PoE standard and maximum power draw, especially models with motors, heaters or strong illuminators.
What a PoE Camera System Needs
The typical setup is straightforward: a PoE switch or a PoE-equipped NVR at a central panel or rack, one cable to each camera, and a recorder with enough storage for the retention you want. The recorder can be a dedicated NVR or software on a server, depending on the system.
Because everything runs back to one place, the cameras stay on a controlled wired segment. That makes it simple to keep them off the general home network, which is good practice for devices that do not need internet access to record.
Placement is the flexible part. A PoE camera can go anywhere a cable can reach — a soffit over a driveway, a corner of a block wall, above a gate — with no dependency on a nearby outlet or on wireless signal reaching that spot.
Why Installers Favour PoE for Cameras
Cameras are the part of a property that should keep working when other things do not. A wired camera does not drop off when the Wi-Fi is congested, does not need a battery changed and does not compete with streaming traffic for airtime. Continuous recording depends on the camera, power supply, recorder and settings. Battery-powered models may have additional recording limits.
There is also a single point of control. Power-cycling a camera means toggling its switch port, usually remotely, instead of getting a ladder.
The trade-off is installation effort: every camera needs a cable pulled to it. On a finished house that is real work, which is why camera locations and cable routes are worth planning before anything is mounted.