Changing two prong electrical outlets to grounded three prongs

Jabar714

Like many of post(er's), I just brought a new house that has many two prong outlets. I have noticed that that two prong outlets have a metal box with a wire secured with a screw type of clip on the inside bottom of the box. This is not including the wires going directely into the two pronged outlet. I would like to covert all of the outlets to three pronged. The three pronged outlets have a small green screw. Can I attached the wire that is secured to bottom of the box to the green screw? It that safe/up to code? Thanks.

nap

what kind of wire is attached to the metal box?

Jabar714

Looks like copper wire

nap

It sounds like you have an equipment grounding conductor (EGC a.k.a. ground wire).

If so, you can use either a self grounding receptacle where the connection to the box is a legal ground (receps must be listed as self grounding), or you could attach a ground wire to the green screw on the recep and attach it to the box.

If you are comfortable opening your electrical panel, you should do that and check to see if there are actually 3 conductors coming from those receps. That is to verify what you area seeing is actually a grounding wire.

Flux

When in doubt (or when there is no ground wire present), it's my understanding that it is always ok to install a GFCI outlet. That's what I did in my old house for outlets where we wanted 3 prongs but the box wasn't wired for it. Obviously this is a more expensive solution but it will definitely work and might be considered safer.