Provided is a brush assembly for transferring lightning current between a first structure and a second structure, which brush assembly includes a holder realized for mounting to one of the two structures; a recess formed in the holder, which recess is shaped to accommodate a brush and to expose a first brush face; and a first displacement means arranged to move the first exposed brush face against a surface of the first structure; and wherein the recess is shaped to also expose a second brush face, and the brush assembly further includes a second displacement means arranged to move the second exposed brush face against a surface of the second structure. Further provided is a lightning protection circuit of a wind turbine; and a wind turbine.