Electrical – What can happen if 24vdc is applied to an Ethernet port


We have a device with two RJ45 ports. One of these ports is for receiving 24vdc on pins 7(-) and 8(+) to power the device. The other RJ45 port is an Ethernet connection. The ports are of course labelled to advise against such a thing, but is there guaranteed damage if someone accidentally plugs the RJ45 power cord into the Ethernet connection. Or, would it depend entirely on how robust the implementation of the NIC card is?

This strange situation is due to this being an engineered system of several different products from different companies.

Best Answer

Pretty sure that 24V connected to pins expecting 3V or 5V is going to damage something. Starting with the magnetics in the ethernet connector.