I am not sure how Wikipedia can be more explicit, they even have a table showing the voltages and wattages of the different standards. [0]

According to that table, the latest standard, 802.3bt Type 4, can provide 71 W to the device at the end of the cable (and inject 100W into the otherside).

[0] https://en.wikipedia.org/wiki/Power_over_Ethernet

I think it's something like 30W over a single ethernet cable. I'm running a few devices with PoE that are not network enabled, just conveniently located near an ethernet cable that's not near a power outlet.

Depends on how you define "network equipment" :)

Unifi is selling LED panels, that are powered over PoE and controlled over Ethernet.