Grounding old outlets
Here's a URL for helpful wiring info. http://www.danswiringpage.com/
[This message has been edited by rpxlpx (edited February 09, 2001).]
Wiring a ground wire is virtually the same as re-wiring the entire house: it is a big deal, especially through finished walls. You can do it, but you will need to figure out the electrical plan and how wires run through the house to service that plan. As Electric Bill wrote, please read up on doing it if you plan to do it yourself. Buy one of the Electrical Wiring Books. Homne Depot just came out with one, and Black and Decker publishes one that I use that is great.
Metal conduit is fine for a grounda, although not perfect. It is less preferable to a seperate ground wire because it is exposed, which could shock you if a short circuit occurs. The current returns through the ground in a short circuit, so the metal conduit will be hot with electreicity in the event of a short circuit. Even if buried inside a wall, it couyld contact some metal part that is exposed, and that metal part would then become electrified. Not so with ground wires that are covered by sheathing.
The other problem with using conduit as a ground is that there is a greater chance that the ground will be interrupted if, say, someone later removes the conduit somewhere along the circuit and replaces it with NM cable, not knowing that the conduit served as the ground. Then the ground will be incomplete, and the same as if there was no ground.
As a result, if you have metal boxes and metal conduit or armored cable, test the metal conduit for continuity before relying upon it as a ground. Touch a circuit tester on the hot wire and the metal box. If it lights up, then it can serve as a ground. If not, there is an interruption somewhere along the circuit, and it will not work.
[This message has been edited by Lawrence (edited February 15, 2001).]