Maximum voltage used in PoE systems is 57VDC. For longer distances they should be calculated and considered. In our case, the router is less than 5 meters way from the switch, so the voltage drop is irrelevant. If the voltage drop is relevant, then you should consider increasing the voltage supply in order to compensate the drops through the cable and have the device’s nominal voltage in its terminals. For most uses, specially for low wattages, voltage drops in a PoE cable are ignored, however, for longer distances they start having considerable values which can change the performance of the network devices.

According with the application, voltage drops should be considered. The injector and splitter should be always used together. To avoid the risk of damaging network devices, it is never advised to inject the PoE signal directly anywhere but the splitter, unless you are absolutely sure about the device’s characteristics and about what you are doing. 1Gbps networks already use all the twisted pairs for data transmission, so the PoE technology is applied differently, through a technique called Phantom Power, therefore this adapter is not suited for those networks. As mentioned before, the PoE technology uses the 2 twisted pairs that are not used on the ethernet cable, however, this is only true for 10 and 100Mbps networks. It’s necessary to guarantee that these pins are left opened, preferably even isolated. If this is not done or if there is any kind of anomaly that imposes voltage in these pins, the network devices might be damaged. Once again we remind that in the injector and splitter, the tips of the twisted pairs 4, 5, 7 and 8 (blue, blue/white, brown/white and brown) must be cut and left in open circuit. Finally we also tested adjacent pins to make sure there were no short circuits anywhere. We also tested if pins 4, 5, 7 and 8 didn’t have continuity, once they are cut in the adapters and left opened in each side. Before trying it, we tested the conductivity of each pin, for that we connected the injector and the splitter with an Ethernet cable and then checked if pins 1, 2, 3 and 6 had continuity, from the injector to the splitter, and the same with the DC connectors. The power supply is sent through another cable and will connect the DC plug to power the Router, however it’s not visible in this image for it is behind the Ethernet cable. The data will be sent through that tip of Ethernet cable, which will connect to the Wireless Router.

In the second image you can see the RJ45 connector that will receive the PoE signal, where then the data will be separated from the power supply.

There are however connectors with mechanical contacts that don’t require any soldering. If you look closely you can notice that the RJ45 connector is a little melted, this is because the material is reused from old electronic devices, the same goes for the perfurated PCB. In the first image you can see the tip of the cable that will come from the switch and the DC input connecting to the RJ45 plug.

Earthnet adaptor