Abstract: In a multiple-phase electrical distribution apparatus, a number of barrier panels formed of dielectric material are provided for separating electrical transmission components disposed within the apparatus. The barrier panels may be manually placed in and lifted from a working position within the enclosure, and are supported in the working position by a mounting bracket extending horizontally in a direction parallel to the direction in which the components are spaced. The bracket includes a transverse slot disposed between the electrical transmission components and defining a pair of bearing surfaces which grip opposed surfaces of the barrier panel when the lower edge of the panel is inserted in the slot. Also, the barrier panel engages a slot formed in the enclosure above the bracket to stabilize the barrier panel against lateral movement.