The useful answer is rarely “buy the biggest number.” This guide turns the specification sheet into an installation decision you can defend after dark, after handover and when footage is actually needed.
Calculate the real PoE load
Power over Ethernet keeps an installation tidy, but only when the power budget is designed rather than guessed. Add each camera's maximum draw—not its typical idle draw—then reserve headroom for cold starts, infrared LEDs, heaters and future devices. A switch advertised with many PoE ports can still have a total budget too small to run all of them at full load.
Separate cameras with a VLAN
Keep cameras on a dedicated VLAN and deny direct internet access unless a documented feature requires it. Administrators should reach the recorder through a controlled management path. Use unique credentials, disable unused discovery services and record every static address in a handover sheet.
Build cable runs that stay reliable
Copper Ethernet is normally limited to 100 metres per segment, including patch leads. Outdoor links need UV-rated cable, proper drip loops and surge protection; runs between buildings are often safer on fibre. Label both ends before termination and test the cable rather than assuming a link light means the run is healthy.
Commission the system against a written evidence goal. Save reference images and settings so future maintenance can spot gradual changes.
Can another person prove the system still works?
Record the final view, night image, bitrate, alerts, firmware and access method. A system is not finished until the owner can verify recording and export without the installer standing beside it.
Every site is different. Confirm manufacturer instructions, electrical requirements, privacy obligations and local regulations before installation.
Frequently asked questions
Should PoE security cameras be on a separate VLAN?
Yes, where the network supports it. Segmentation limits exposure and makes camera traffic and access rules easier to control.
How much spare PoE power should a security camera switch have?
A practical target is at least 20 percent headroom above maximum planned device draw, with extra allowance for heaters, infrared LEDs and future cameras.