An equipment mounting frame comprising two side support structures of a selected height, each of which comprises one or more upright members defining a width of that side support structure and a foot structure extending from at least one end of the upright members. The foot structure defining a depth of that side support structure and extending across at least one quarter of the width and carries an upright series or row of fixing members wherein the two side support structures are connectable together at a distance from each other to enable equipment trays or boxes to be mounted in superposed array between the side structures by the fixing members are formed to be nestable together when unconnected to each other for shipment or storage within a volume less than twice the volume defined by width, depth, and height.