Thanks for the response. To clarify, I'm not looking to use this with -48V. Instead I'm wondering whether the  negative of the POE supply as well as the negative of the DC power supply plug are connected to ground inside the switch (the metal case, ground nut etc). Perhaps your answer re -48V does a...

Anyone have any feedback on this?

thanks
Jon

I'm installing a  CCR1009-8G-1S-1S+PC and it seems that the negative of the POE supply as well as the negative of the DC power supply plug are connected to ground (the metal case, ground nut etc). Can someone confirm that this is the case? I'm using these with Netonix WISP switches that provide POE ...