Abstract: An arrangement for retaining wires or cables inside a trough having base wall, and first and second side walls extending generally parallel to one another from the base wall. The arrangement includes one or more pairs of trapezoidal retainer plates supported on the side walls so that each pair of plates are in confronting relation to one another above the trough. Each retainer plate has a base portion, and an end portion forming an outside edge which defines an approximately 45-degree angle with respect to parallel side edges of the plate. The outside edges of each pair of confronting plates form a gap through which wires or cables can be inserted into or withdrawn from the trough. The gap forms an acute angle with respect to the side walls of the trough, so that inserted wires or cables will be retained by each pair of confronting retainer plates.