An electric connector assembly disclosing various embodiments, each of which includes a connector body having a frustro-conically shaped outlet end portion that converges toward the outlet opening and having a complementary frustro conically shaped retainer ring circumscribing the outlet end portion wherein the retainer ring is integrally formed with a locking tang and ground tangs arranged to be snap fitted to a knock-out hole of an electric box. The latest embodiment includes a frustro-conical retainer ring having an auxiliary tang arranged to permit the connector assembly to be obliquely inserted and locked to a knock-out hole of an electric box using a minimum of applied force for effecting a snap fit connection to both lock and electrically ground the connector assembly to the electric box and a method of installing the associated connector body to an electric box.