Abstract: An isolator assembly (20) is provided for selectively isolating or connecting first and second bus bars (31) located on opposed sides of a wall (22). The assembly includes mounting means (24), for mounting the assembly (20) in the wall (22), and a through-wall conductor. The through-wall conductor (28) is supported by the mounting means (24) and has a contactor (30) capable of selectively making electrical contact with at least one of the bus bars (31). The conductor (28) is displaceable between a connecting position in which the conductor (28) connects the first and the second bus bars (31) and a disconnecting position in which the first and the second bus bars (31) are isolated from each other.