Yes, you can do it, but be aware that there are probably no ground wires. The purpose of the 3rd prong is for the ground connection. I've been told that if in order to meet code and safety requirements, (when there is no ground wire) you must use a GFCI (ground fault circuit isolation) outlet in place of each old 2-prong outlet. These cost quite a bit more than standard outlets, but I think it's worth it to allow you to properly and safely use modern electrical devices.

One GFCI and protect all the outlets downstream from it, so not every outlet needs to be GFCI.

Don't buy the cheap outlets. And don't use the push-in method. Just pushing the wires into the back is easy, but leads to poor connections (failure, fire) in a few years. Use the screws to make a solid connection. And only 1 wire under each screw.

You can definitely do it yourself, and it is not difficult, but as rxplxqrstomnlop (or whatever his name is) said, you need to pay attention to grounding. It is possible your outlets are still grounded. Your circuit should contain three wires: one black or red (the hot), one white or grey (the neutral, which returns the current to the circuit breaker), and one green or bare/naked (no plastic coating) (the ground). The ground wire could be attached either to the plug, itself, or the box (if it is a metal box). If you only have two wires going into your box (or four: two coming in and two going out to continue the circuit), then you do not have a ground. Three or six wires coming into the box probably means that you have a ground.

If you have no ground wires, you can still do it yourself by putting in a GFCI outlet. Doing so is the only way to safely replace those two-prong outlets. They are actually safer than grounded circuits because they trip more easily when there is a ground fault. They are also very safe to install because they will usually trip if you wire them incorrectly, unlike an ordinary outlet that will still work if it is wired incorrectly. They also come with instructions.

As for the push-through vs screw-on installation mentioned above, the push-through spots on my GFCIs are all secured by screws: you push the wire into the spot and then tighten the very same screw to create a connection. It does not just grab the wire like an ordinary outlet plug would. It is also safer to install it that way than wrapping the wire around the screw because the wire is completely enclosed in the unit if pushed into the hole and then secured, whereas the wire can slip off if merely wrapped around the screw on the side.

DO NOT simple replace a two-prong outlet with a three prong outlet without grounding the outlet. You will have a ground wire that does not work, and even if you know the difference, you will mislead future owners or occupiers into believing that the plug is properly grounded, which could kill somebody if a short circuit occurs.

Also, make sure you turn the breaker off or unscrew the fuse to that plug before working on it.

[This message has been edited by Lawrence (edited February 02, 2001).]