An electric connector assembly made up of a connector body having an inlet end portion, an outlet end portion, and a bore communicating the inlet end portion to the outlet end portion; and having a frustro-conical retaining ring mounted on the outlet end portion wherein the retainer ring includes locking tangs and one or more grounding tangs wherein the free end of the grounding tang defines the trailing end of the retainer ring. The locking tangs effect a snap-fit locking arrangement while the grounding tang effects an electrical grounding of the connector assembly, when connected to a knock-out hole of an electric box or panel. Various embodiments are disclosed wherein the grounding tang is formed so as to enhance the electrical grounding effect between the connector assembly and the electric box or panel connected thereto. An embodiment of the invention also provides for an installation tool to engage the retainer ring so as to facilitate the securing of the connector assembly to a knock-out hole of an electric box or panel.