Power over Ethernet (PoE) basics and beyond

POE switches can have more jacks than they can provide power for. I have five pan-tilt-zoom (PTZ) cameras but learned they can need up to 40 watts each, preventing plugging them all into a particular POE switch I had. Chaining a couple of switches solved the problem, be beware how much power your devices need to consume.

Is it actually likely that all 5 would be drawing full power at once though?

It's normal in household wiring (at least here in the uk) for circuits to be somewhat undersized based on the concept of "diversity" (i.e. it's highly unlikely every socket on the circuit will be drawing 13A simultaneously)

I would expect power consumption to be fairly consistent for something like a surveillance camera that emits a stream 24/7.