Patent ID: 7612975

Claim:
A power supply line for powering electronic equipment situated at a first location from a power supply situated at a second location remote from the electronic equipment, wherein the first location has a first local ground potential and the second location has a second local ground potential, the first location being sufficiently remote from the second location that a lightning surge current may induce a difference between the first local ground potential and the second local ground potential, the difference in potential being of a magnitude so as to risk causing damage if it were applied to the electronic equipment, the power supply line comprising a balanced differential power transmission path comprising two conductors connecting the power supply to the electronic equipment, the power supply being operable to provide a potential difference on each of the two conductors and the electronic equipment being operable to derive a potential difference between the two conductors, the power supply line further comprising at least one isolating transformer in the power supply line for providing isolation from the difference between the first and second local ground potentials associated with lightning surge currents, wherein the power supply line is not connected to the first or second local ground potential so as to achieve isolation from ground potential rise associated with lightning surge currents.