I’ve purchased several of these four port passive POE injectors.
They have a center-positive barrel jack as well as a pluggable terminal block for input power connections. They are pretty handy for testing and temporary field deployments.
However, there is one shortcoming you’ll want to fix if you plan to use this in a permanent installation. Out of the box, there’s no provisions for bonding the shielded Ethernet jacks to ground. In fact, the two sides are not even connected to each other.
My solution was to open the case by removing the two screws partially covered by the silver label and solder a grounding wire and jumper to the outer shields of the jacks.
A small notch can be cut in the cover to allow it to be re-assembled. The eyelet can be secured to an electrical box cover screw. Now if you use the recommended shielded cable and connectors between the injector and your outdoor node, it will help protect your equipment from ESD damage.
Ham Radio Mesh Networking 