Youtube video: 2 prong outlet to 3 pront while adding a ground

[Mustang51js]

Yeah to me it looks like a plastic box with bx wire in it, that means no ground, you would need to replace the box with a metal box to do it right. But more than likely they did more than one box like that. What you can do is take the clip you had onto the box and clip it on the metal of the wires inside the box, if you get ground then you only need to replace that box. If you can take a pic of the inside of box and check to see if it actually is a plastic box,which is what it looks like but hard to tell.

 

[hoffman912]

I thought the only way to replace 2 with 3 was if you did a GCFI outlet (assuming you're not rewiring, and leaving old service with + and - and no ground)

 

[miamivice]

Good information!