A rotor has a rotor body with at least one slot receiving a blade. The blade has an outer surface, at least at some areas, formed of a first material and having an airfoil extending from a dovetail. The dovetail is received in the slot. A diode is in contact with a portion of the dovetail formed of a second material that is more electrically conductive than the first material. The diode is in contact with a rotating element that rotates with the rotor. The rotating element is formed of a third material. The first material is less electrically conductive than the third material. The diode and the rotating element together form a ground path from the portion of the dovetail into the rotor. An engine and a fan blade are also disclosed.