A wind turbine blade assembly, includes a wind turbine blade and a lightning protection system including an internal down conductor inside the wind turbine blade and multiple air termination devices having a receptor, which is electrically conductively coupled to the down conductor, wherein the length of the wind turbine blade assembly is divided into a first part having the internal down conductor and spanning from the blade root to at least one first air termination device and a second part spanning from the first air termination device to the assembly tip, wherein the lightning protection system further includes a second air termination device in the second part, and an external, electrically conductive strip extending between a pair of a first and a second air termination devices in the second part and being electrically conductively coupled to their receptors.