Converting 2 prong to 3 prong

[kactuskid]

So the supply cable actually has a ground wire run with it or externally?

What's important to know is where the other end of this ground wire is landed. If this circuit doesn't have a ground wire comming into the main panel then where is it getting it's ground from. Any ground wire added after the fact should be run all the way back to the main panel

[Snoonyb]

"So I went back to the outlet boxes and removed the outlet. I seen at the back of the box a little piece of wire so I removed the clamp inside the box that was holding the wires in place. Low and behold wrapped around the insulation of the wires there was a ground that was hidden and was touching the box."

Walla, you've discovered the holy greil. I knew it had to be one of the entrepreneurial methods devised in the evolution to what exists today.
Now, you know to check for voltage to ground before replacing the recep. to 3 prong.

[HayZee518]

Older wires in new(er) panels always had the ground wrapped around the white and stuck into the neutral bar. The neutral bar of main panels are bonded to the enclosure through a screw or bonding jumper. Sub panels which come off the main have the neutral isolated above ground and an auxillary strip grounded to the enclosure. The neutral receives the white wire, the aux connects to the bare ground wire. All branch circuit bare grounds go to this aux bar, while the whites to the neutral strip. The wire you describe is early romex that is without a ground wire. Some had the ground some did not. The romex outer cable is a silver waxy feeling thing. If you scratch the surface the black tarry stuff was underneath it. A paper wrap was wound around each thermoplastic insulated conductor and this whole mess was encased in the tar and silver coating.

[HayZee518]

Back-wrapping or so it is called was common for electricians and homeowners BUT it lacks originality. It was possible to ground out the box this way but there was no "intimate" connection with the box as in "around a screw." Also what sometimes happened is that the wire was so firmly clamped that the wire insulation was smashed and created a high resistance short that wouldn't manifest itself until it was too late [FIRE! FIRE!]

[jtfoxman]

HayZee is right on about the type of wire, he described it a lot better than I did.
The ground wire was in the insulation with the other 2 wires, not seperate. And like HZ said the ground and the white wire are together in the main panel.
I also loosened the clamps in all the boxes so the wire had a touch of play in it. I had to take all the clamps out to get at the ground so it wasn't extra work. Just getting them clamps back in was a pain.
Now I have 2 oulets left that are not grounded in my 1 bedroom and the attic. It is all the same circuit. They all have grounds in the box but they all feed from the attic, just 1 light up there, that is only 2 wire. Can I run a ground from up there to the water main where the main breaker connects to so all my outlets are grounded? What would the simplest way to do this be? Do I have to run the ground inside the walls, house or outside. If it is outside should it be covered, I would think it would have to be.
I know this post is a little long and has been going on for a while so thank you all for staying tuned to my post.
I'm pretty good at all this electrical stuff as I do it all myself. I just need some expert opinions every now and then.