I recently bought a house that doesn't have grounded outlets. I want to put grounded outlets in a few of the rooms at least. The current outlets have metal boxes and metal conduit running to the breaker box. Can I just put in some grounded outlet in the box, or do I need to run a jumper from the new outlet to the box for ground, or run all new wire? I can't see any easy way to hook up a jumper to the box. Any help would be appreciated.
It depends on how good a ground you want. If you only want to keep the house from burning down, a connection to the metal box and conduit will work. On the other hand, if you're trying to protect computer files and sensitive electronic equipment, you will want an actual ground wire that connects to the panel ground bus. The problem is static electricity. It doesn't take much to confuse a computer, especially around a thunderstorm. I used to install and service computers and have heard some professional electricians say "a ground is a ground". Wrong. Many times I've seen computer problems cleared up by running an isolated ground wire to the bus, even when there is already a ground wire under a screw on the side of the breaker box or elsewhere. The ground wire should be as heavy or heavier than the hot wire for that circuit. Today's computers are not as sensitive as they used to be, but it doesn't take even a direct hit by lightning to take out your tv, vcr, cordless phone, answering machine, etc. A good ground is not a cure-all but it will help.