Wall flange – Roof, wall and floor flanges are available for X-way & C-way busway. When the busway run passes through a roof, wall or ceiling, a flange should be used. Flanges do not offer support to the busway. Flanges provide a means of covering the hole created in the existing structure. The standard dimension of a wall opening should be 30mm larger than the external dimensions of the X-way & C-way Busduct.