A wind turbine rotor blade having a blade shell with a generally chordwise layup of fibre plies and a generally spanwise spar cap. A lightning conductor extends over the spar cap, and the spar cap includes conductive material. An equipotential bonding element electrically bonds the lightning conductor to the spar cap. The equipotential bonding element extends between an outboard edge of one stack of the fibre plies and an inboard edge of an adjacent stack of the fibre plies, which overlap to define an overlapping edge region.