PoE budget calculation for security cameras
A PoE switch needs both enough ports and enough total power. Infrared LEDs, heaters and PTZ motors can push cameras above their typical consumption.
Calculate the load
Add each camera's maximum wattage and multiply the total by 1.2. Eight 10 W cameras need 96 W including reserve, so a 120 W budget is a reasonable choice.
PoE classes
802.3af, 802.3at and 802.3bt provide different power levels. Total budget is not enough if an individual port cannot supply the camera's class. Check both limits.
Cable distance
Copper Ethernet is designed for 100 metres including patch leads. Long or poor cable increases voltage drop and errors. Outdoor runs also need suitable cable, surge protection and grounding.
Leave expansion room
Allow spare ports, an adequate uplink and VLAN capability. A 16-port switch for twelve cameras is often more practical than a fully occupied unit.
Frequently asked questions
Will 120 W run eight cameras?
Usually, if each camera is at most 10 W: the reserved load is 96 W.
Can PoE damage a camera?
Standards-compliant devices negotiate power; passive PoE requires special care.