Flashover protection covers are provided in a continuous length for covering power line spans between supporting structures. A flexible panel includes an inner surface and generally parallel opposite edge portions configured to be joined together to form a first longitudinally extending chamber. A longitudinally extending first wall is connected along an edge portion thereof to the inner surface of the panel. The first wall has an opposite free edge portion and is configured to form a second longitudinally extending chamber within the first chamber. The second longitudinally extending chamber is configured to enclose a power line when the panel edge portions are joined together. A second wall is connected along an edge portion thereof to the inner surface of the panel and is configured to inhibit electrical arcing from the power line into the first chamber between the first wall free edge portion and the panel inner surface.