Abstract: A front extrusion having a generally U-shape provides top and bottom walls for the enclosure with a front wall extending therebetween. Integral extruded flanges are formed on the outer surfaces of the top and bottom walls and fastener channels are extruded on the inner surfaces of the top and bottom walls near the ends thereof as well as on the inner surfaces at the junction of the top and bottom walls with the front wall. Circuit board grooves are formed on the inner surfaces of the top and bottom walls and a shaped rear-cover groove is formed internally at the free end of each of the top and bottom walls. A rear cover which may be a plate or a rear cover extrusion is inserted laterally in the rear cover groove and trapped therein by left and right side plates which complete the enclosure. Each of the side plates has a hole pattern therein aligned with the fastener channels in the body extrusion.