Wind turbine blade assembly (1a, 1b, 1c, 1d), comprising - a wind turbine blade having a blade root for connection to the hub of a wind turbine, - an assembly tip, which is either formed by a blade tip of the wind turbine blade or an add-on tip of a wind turbine blade add-on attached to the blade tip of the wind turbine blade, wherein the wind turbine blade assembly (1a, 1b, 1c, 1d) spans a length from the blade root to the assembly tip, and - a lightning protection system comprising an internal down conductor inside the wind turbine blade and multiple air termination devices (4, 6, 14) having at least one receptor, which is electrically conductively coupled to the down conductor, wherein the length of the wind turbine blade assembly (1a, 1b, 1c, 1d) is divided into a first part spanning from the blade root to at least one first air termination device, in which the internal down conductor extends, and a second part spanning from the first air termination device to the assembly tip, from which the internal down conductor is absent, wherein the lightning protection system further comprises - at least one second air termination device in the second part, and - at least one external, electrically conductive strip extending at least between a pair of a first and a second air termination devices (4, 6) in the second part and being electrically conductively coupled to their receptors, characterized in that the strip is electrically conductively coupled to the receptors of the respective first and second air termination devices (4, 6) by a spark gap, wherein the strip at least partly surrounds at least one of the receptors in a predefined distance. - a wind turbine blade having a blade root for connection to the hub of a wind turbine, - an assembly tip, which is either formed by a blade tip of the wind turbine blade or an add-on tip of a wind turbine blade add-on attached to the blade tip of the wind turbine blade, wherein the wind turbine blade assembly (1a, 1b, 1c, 1d) spans a length from the blade root to the assembly tip, and - a lightning protection system comprising an internal down conductor inside the wind turbine blade and multiple air termination devices (4, 6, 14) having at least one receptor, which is electrically conductively coupled to the down conductor, wherein the length of the wind turbine blade assembly (1a, 1b, 1c, 1d) is divided into a first part spanning from the blade root to at least one first air termination device, in which the internal down conductor extends, and a second part spanning from the first air termination device to the assembly tip, from which the internal down conductor is absent, wherein the lightning protection system further comprises - at least one second air termination device in the second part, and - at least one external, electrically conductive strip extending at least between a pair of a first and a second air termination devices (4, 6) in the second part and being electrically conductively coupled to their receptors, characterized in that the strip is electrically conductively coupled to the receptors of the respective first and second air termination devices (4, 6) by a spark gap, wherein the strip at least partly surrounds at least one of the receptors in a predefined distance.