Replacing several 3 prong outlets in my 1968 home. Tried searching to find an answer but most questions seem geared towards replacing 2 prong outlets with 3 prong and don't apply here.
My wiring appears to be romex with a bare copper ground wire. After removing the outlet covers and pulling the outlets (all 3 prong) out of their junction boxes, I've found that each has the hot and neutral wires connected to the outlet and the ground wire connected to the junction box. Each outlet has a black screw in the bottom corner which I assume makes contact with the metal box and provides a ground path?
What is the correct way to replace these outlets? I assume I need to get some bare copper or green insulated wire and connect it to the outlet ground screw on one end and connect it to the metal Jbox via installing another screw above the "GR" label on the junction box in my photo?
Edit:
Attempting to summarize info in multiple answers. It seems my options for properly wiring the new receptacles require me to update the grounding of the box shown in the left photo, where the ground conductors are currently tied around the cable clamp screw in the middle. Google searches tell me that used to be an approved bonding method but is no longer allowed.
To properly ground the jbox and receptacle I can:
A) Terminate a pigtail on the box ground screw hole (will require a 10-32 green ground screw), terminate a pigtail on the receptacle ground screw and tie the 2 pigtails and 2 ground conductors together with a wire nut.
B) Terminate a longer pigtail on the box ground screw hole (will require a 10-32 green ground screw), connect it to the 2 ground conductors in the box with a Greenie wire nut and terminate the other end of the pigtail (which extends through the small hole of the Greenie) on the receptacle ground screw.
In either case do I also need to match my pigtail wire gauge to my 2 ground conductors coming into the box?
Best Answer
The ground screws do not make contact with the box. They're intended to secure a pigtail from the ground wire bundle (or a passthrough loop). On modern outlets they'll be green.
Some outlets are self-grounding. They have small tabs or wire springs behind the screw mount ears that make a positive connection.
You can either replace your outlets with self-grounding ones, or simply attach the grounding conductor with the screws. The ground wires should still connect to the box if it's metal. That does appear to be a grounding screw hole in your photo. Be sure to use the proper screw (often 10-32 with self-cutting threads) to be legal.