As I'm using more and more PoE, I'm getting nervous about someone coming along and swapping a network cable to another port and causing trouble. For example we could have a mixture of 24/48V passive or 802.3af/at in the same system.

Is there a standard or "best practice" out there that is applicable? For example, we have a "best practice" going back to company inception for speaker wires, remote IR wiring, audio and video. I can walk into any system and know left from right, power pins, IR data, and ground.

I'm particularly worried about the know-it-all electrician-alarm-IT guy running rough shod over my system.

Maybe I should follow the technique we used in a lab I worked at. If we had something that we wanted everyone to stay away from, we'd tag it "Danger 1,000,000 nepers".

Get managed switches that you can name ports.

Other than that, don't worry about PoE screwing up non-PoE devices, as long as you use quality switches and NOT power inserters.

I try to use red cables and keystones for POE. "Try to" is the key word. But as Mario stated, use decent POE switches and they won't send POE to non POE devices.

Haven't ever had ANY POE switch damage a non-POE device.

This is true as long as you are dealing with 802.3af 48V PoE. The reason it won't harm anything is the whole standard was designed to first send a much lower voltage, looking for a signature that only 802.3af devices have, then sends full voltage.

But "passive" PoE (commonly 24v) is sketchy because voltage is present at all times and could definitely result in damaging a non PoE device if you weren't careful.

I don't have any tips on best practices for labeling other than hoping the next technician is smart enough to know what kind of device he is working with and exercise the necessary caution.

Ubiquiti UniFI switches can auto sense and power 24v passive and 802.3 at/af devices.

Do a strip of red electrical tape on POE cables and cable amplifiers that use coax for power supply. Or any other low voltage wire used that has power on it.

+1 On red tape markers on visible patch cables.