One of the most common defects I find when inspecting older homes in Kansas City is ungrounded three prong outlets. This usually happens when a home has older wiring and the homeowner replaced a two prong outlet with a three prong outlet.
Most likely because the homeowner needed to plug something in that had the third prong on the top (or bottom, depending on how your looking at it). When you go to the hardware store and pick up a two prong outlet, it’s about three bucks. You can get a similar three prong outlet for a bout 50 cents. You get the picture.
What’s the difference anyway…
The older two prong outlets are no longer the norm for construction today. Between 1920 and 1960, the standard was a two prong outlet, which consists of a Hot and Neutral wire. The third wire (the bare wire) is the ground, which didn’t become the norm until around 1962.
That third wire (or the third hole in the outlet) provides and alternate path for electricity, minimizes the risk of electric shock and allows surge protectors to protect sensitive electrical equipment such as computers and televisions.
Have the right tools.
There are a few ways of dealing with ungrounded outlets. The best way is of course the most expensive, which is to have a continuous ground run for each outlet all the way back to the main panel. Without tearing out walls, this is an almost impossible job.
The next best way requires grounding the outlet to the metal box that it’s housed in.
Keep in mind that I’m not a professional electrician, however I have been working with electricity since I was a kid. If you’re not confident you can do this without injuring yourself or burning your house down, please contact a professional.
Do a little research first
Given that the box is grounded in the first place (meaning that the wiring runs through metal conduit all the way back to the main service panel). To test this, pull the outlet out of the box keeping the wires connected to the outlet (be careful not to shock yourself). Use a pig-tail electrical tester (that’s not what I’m using in the picture, and in the picture the box is not grounded) and put one end in the smaller slot and touch the other end to the metal box. If the light pops on, the box is grounded. Then run a bare wire from the ground on the outlet to the back of the box.
There, see how easy that was.
However, if there is no conduit from the box to the electrical panel, you can’t ground the outlet that way. The outlet in the picture would have to be grounded a different way.
On to the next solution…
If the box is not grounded, then the next solution would be to install a GFCI outlet. Although this will protect against electric shock, it will not protect your sensitive electronic devices that require a ground. Also, after you installed the GFCI, you will need to place the little sticker on it that says “No equipment ground” which is included with every GFCI. That way, people won’t expect a ground where there isn’t one.
Oh, and there is one final solution. You can replace the breaker that is connected to these circuits in the main electrical panel with a GFCI breaker. These are special breakers that protect all the outlets on that circuit. These are about 40 bucks per breaker, but it will protect all the outlets on that circuit. Most GFCI outlets are about 25 to 30 dollars each. So if you have multiple outlets that need GFCI, this might be the most cost effective way.
I hope this answers any questions you have about ungrounded three prong outlets. Oh, and by the way, if the house comes with two prong outlets, the procedure for correcting those is identical to the instructions given in this article. The only difference is you have to buy the three prong outlet.