Bonding bushings are not required for grounding a motor disconnect switch with 1/2" rigid metallic conduit in a concentric knockout, when the conduit is not used as the grounding electrode conductor (GEC).The conduit provides an effective ground path for the motor disconnect switch and the wiring contained within it, in accordance with NEC 250.118 and 250.104(D).The use of bonding bushings is primarily required when the conduit is used as the GEC, as specified in NEC 250.104(E). In such cases, bonding bushings are necessary to ensure a continuous and low-impedance grounding path for the entire electrical system. Flag for review