Abstract: A molded plastic enclosure of an electrical disconnect is presented. The disconnect has a switch mounted within the enclosure for manually disconnecting electrical equipment from a source of power. The disconnect enclosure includes a molded base hingedly attached to a cover. The base includes an interior compartment for mounting the disconnect switch therein. The base also includes a plurality of knockouts, which can be removed (knocked out) to provide access for electrical wiring. Each knockout has a plurality of concentric circular sections, each having an angular groove formed on their circumference. The smallest-diameter section includes a groove with a cross-sectional shape having a sharp corner (knife-edge) while the larger-diameter sections include grooves with cross sections having radiused corners. Additionally, the depth of the groove for smaller-diameter sections is greater than the depth of the groove for larger diameter sections.