20A 125V 5-20R Duplex Receptacle, 2-Pole 3-Wire Grounding, Commercial Grade

In February 1968, Hubbell patented the first isolated ground receptacle. Today - when a clean, noise-free ground is more important than ever-Hubbell is still setting the standard. Hubbell uses insulation barrier construction on many models to isolate the ground contacts from the mounting strap. The green grounding screw is connected directly to the grounding contacts. In this way, ground contacts are separated from the mounting strap and also from the conventional grounding system. The isolated ground circuit is completed by running a dedicated insulated ground wire from the system ground buss to the green grounding screw.