A joint on an aircraft, the joint comprising: a first component; a second component; and a bonding lead which provides an electrical pathway between the first and second components. The bonding lead comprises a conductive core and a sheath which covers a substantial length of the core and has a lower electrical conductivity than the core. The path of least electrical resistance between the first component and the core of the bonding lead comprises the sheath, typically with an electrical resistance between 50 kΩ and 50 MΩ. By making the electrical resistance of the core much smaller than that of the sheath, the total resistance of the bonding lead remains substantially the same regardless of its length.