One cable, two jobs
Power over Ethernet, usually shortened to PoE, sends electrical power along the same twisted-pair network cable that carries data. A camera that supports it needs only a single cable run back to a switch or recorder. There is no separate power adapter near the camera and no need for an outlet at the mounting point.
For cameras mounted under eaves, on poles or high on a wall, this is a real convenience. Outlets are often missing in those places, and running a data cable is simpler than arranging mains wiring outdoors.
What you need
A PoE setup has three parts that must agree with each other.
- A power source. This is either a PoE-capable network switch, a recorder with built-in PoE ports, or a small single-port device called an injector that adds power to one cable.
- A cable. Standard network cable of an appropriate category, typically with solid copper conductors, connects the source to the camera.
- A powered device. This is the camera itself, which must support PoE or be paired with a splitter that separates power from data.
If your camera does not support PoE, a splitter can sometimes bridge the gap, but it adds a part to fail and needs care to match the voltage. Checking the specification sheet of each device is more reliable than guessing.
Standards and power budgets
PoE comes in several standards, which allow different amounts of power per port. Roughly speaking, the older basic standard supports modest cameras, a later standard supports more power-hungry models, and still newer ones deliver much more for devices such as heated or motorized units. The exact figures differ by standard, and the power available at the camera is a little lower than what leaves the switch because some is lost in the cable.
Two budgets matter:
- Per port. The camera must not need more than the port can supply.
- Total switch budget. A switch with many ports often cannot power all of them at full capacity at once. Add up the maximum draw of your cameras and compare it with the switch’s stated total.
Features such as infrared lighting at night, heaters, or pan and tilt motors raise power use. This is worth bearing in mind with PTZ cameras and when considering night vision performance, since both can draw more than a small fixed camera.
Distance and cable
Ethernet cable has a commonly cited maximum run of about 100 meters, or roughly 328 feet, between the source and the device. Beyond that, signal and power both suffer. Cheap cable with copper-clad aluminum conductors can perform worse than solid copper, especially for power, and may not meet the standard. If a longer run is needed, an extender or an intermediate switch can help, but that equipment needs its own power.
Outdoor runs need cable rated for the conditions, protected connections and sensible routing. Electrical safety, grounding and local rules differ by place, so consider hiring a qualified installer for anything beyond a simple indoor run.
Benefits
- Fewer wires and adapters at each camera.
- Central power. If the switch or recorder is connected to a battery-backed supply, every camera connected to it can keep running through a short outage. This is a common reason to prefer PoE for important cameras and ties directly into surge protection and backup planning.
- Easier relocation. Moving a camera usually means moving one cable.
- A wired connection that avoids many Wi-Fi problems, which is part of why wired systems are often described as steadier than radio-based ones.
Drawbacks
- You need to run cable, which can be hard in finished buildings.
- The central switch becomes a single point of failure for all the cameras attached to it.
- Higher-power devices can make cables and switches warm, so ventilation matters.
- PoE equipment costs more than basic switches, though it may save on adapters and electrical work.
Network considerations
Cameras on PoE are still network devices. They add to the traffic on your local network, which is discussed under camera bandwidth, and they should be kept up to date and set up with unique passwords. Placing them on their own network segment is a common practice for limiting exposure.
Before buying, list your cameras, note their power class and maximum draw, measure the cable runs, and choose a switch with some spare capacity. Results depend on the exact equipment, so follow the manufacturers’ specifications for each part.