Abstract: The present invention includes an aircraft fuel tank protective barrier which includes a transformer. The transformer has a first winding coupled to a fuel tank indicator through wiring which forms a threat side of the barrier, and has a second winding coupled to one or more sensors in a fuel tank which forms a protected side of the barrier. The transformer is operable to magnetically couple normal signals between the fuel tank indicator and the sensors in the fuel tank while limiting an amount of energy delivered to the fuel tank in the event of a fault experienced on the wiring.