Patent ID: 8779786

Claim:
A method for detecting a resistance of a cable, the method comprising: applying power to a first end of a first and a second conductive pair of the cable; measuring a first voltage across the first end of the first and second conductive pairs of the cable; measuring a second voltage across the first end of a third and a fourth conductive pair of, the cable; determining a resistance of the cable using the measured first and second voltages, wherein a second end of the first, second, third and fourth conductive pairs of the cable are connected to a first, a second, a third and a fourth input terminal of a powered device, respectively; and bypassing a rectifier disposed within the device such that the second voltage across the first end of the third and fourth conductive pairs of the cable is substantially the same as a third voltage across the first and second input terminals of the powered device, wherein the rectifier is connected to the third and fourth input terminals of the powered device and a current flowing through third and fourth conductive pairs of the cable is substantially zero.