A spar cap for a rotor blade of a wind turbine is disclosed. The rotor blade includes a blade root and a blade tip, leading and trailing edges, pressure and suction sides, and at least one spar cap configured on an internal surface of either or both the pressure or suction sides. The spar cap includes one or more layers of a first material and a second conductive material contacting at least one of the layers of the first material. Further, the conductive material is different than the first material. Thus, the conductive material is configured with the first material so as to create an equipotential spar cap.