In a nutshell, I want to be reassured that I can plug any laptop into a powered powerbox and it won't blowup the laptop's ethernet port.
I know that Ethernet is an electrically differential signal. So each pairs can have a different potential and as long as the pairs are electrically isolated, then no current drawn (no short circuit).
Now what I don't know is if ethernet ports on normal computer have a high impedance and that all pairs are electrically isolated (so no current leaks between pairs)?
Yes, I could test this out with an old laptop and risk the port, but even if the first one survives, one is not enough to generalize to *ANY* laptop (or other device) will survive if there's 24V on different pairs. Can someone that has tried this many times tell me what has been their experience ? Have you ever had any damages ethernet ports ?
Martin Politick, April 2019.