The two numbers that matter

• Port count: one PoE port per camera, plus at least one spare for the recorder's uplink if it isn't PoE-native, and room for the next camera you add. An 8-port switch for 8 cameras leaves nothing spare.
• Power budget (watts): this, not the port count, limits how many devices you can run. Add up every camera's PoE class. A standard IP camera with IR draws around 6–8W. A PTZ or heated housing draws much more. A 150W switch runs eight standard cameras comfortably. The same eight PTZs could need 250W+. Undersizing this is the most common reason a new camera won't power up even though the port lights.

Which switch for which job?

• NVR with built-in PoE ports: many HiLook and Hikvision NVRs have 4 or 8 PoE ports built in, so a small system on one recorder needs no separate switch.
• Standalone PoE switch: needed once you have more cameras than the NVR has ports, or when cameras and other devices (access points, intercoms) share a run back to a comms cupboard.
• Managed or unmanaged: a managed switch shows per-port power draw and can reboot a stuck camera remotely. Worth it on a commercial site. Unmanaged is fine for a small home install.

What else will I need?

Run Cat5e or Cat6 cable rated for the distance. PoE and standard Ethernet both max out around 100m per run without a repeater or media converter. Beyond that, use a PoE extender or fibre uplink, not a longer copper run. Planning a whole system? Start from IP cameras and work back to the switch.