It's rare to find two-prong outlets in homes these days. Landlords and home owners have slowly switched over to three-prong outlets as more and more devices and appliances need them to power up. Occasionally though, you move into a place that doesn't have a three-prong outlet where you need one, so how do you remedy the situation?
You switch out your two-prong for a three-prong, but there's a lot to consider before you start rewiring your apartment.
Before you start, have an electrician come over to tell you if your building's fuse box has been grounded at all. This will decide what type of outlet you buy. If all your outlets are two-prong than you can easily assume that the building has not been grounded, but if you have a few three-prongs in the mix (say behind your fridge) then your building's wiring may be grounded but your landlord hasn't put in the time and money to convert all the outlets to grounded three-prongs. Either way, it's best to have an expert tell you what's been done and what the safest way to modify is.
What You Need
A drill or screwdriver
Flat head bit
Phillips head bit
An extended Phillips head bit
Grounding wire, if needed
Needle nose pliers with rubber or non-metal grip
New wall outlet -- a standard three prong if you're building is grounded or a GFCI (Ground Fault Circuit Interrupter) if it's not
1. First and foremost, turn off electricity to the circuit you're working on. To make sure you turn off the right circuit, plug a lamp into the outlet you want to replace and turn it on. Flip the circuit breaker switch to "OFF" and your lamp should turn off. Make sure both receptacles on the outlet are no longer conducting electricity, as some outlets have two circuits and others may have a wall switch that controls the top or bottom of a double/duplex outlet.
2. Unscrew the top plate. Most outlet plates are in place via a single flathead screw in the middle. You can use a screwdriver or drill to remove it, just make sure that whatever you use has a rubber or other non-metal grip -- even though you've turned off the power to the circuit you're working on, it's better to be safe than sorry.
3. Remove the outlet from the electrical box. Traditionally there are two screws that attach the outlet to the electrical box. Unscrew both of these and carefully pull the outlet out of the box. Each side of the outlet's mounting bracket will have a pair of color coded wires attached to it. The "hot" (usually black or red) will be connected to the side of the outlet with the shorter plug slot and may be in place via gold colored screws. The "neutral" white wires will be connected to the side with the taller slot via silver screws. If your outlet was already grounded you'll see a bare-copper or green wire coming from a single screw in the back of the electrical box to a green ground screw on the mounting bracket.
4. Move the wires from the old outlet to the new. Carefully unscrew one set of wires (pick either neutral or hot and stick with it until you're done with that side) and connect them to the appropriate screws on the new outlet. Remember, hot wires go on the side with the short slot and neutral wires go on the side with the long slot. Make sure you follow which wires attach to which screws (top or bottom) for both neutral and hot. Generally you can follow where they were placed on the previous outlet as a guide, but the logic goes, wires that come from the breaker panel need to be attached into the screws designated "load" on the mounting bracket and wires that go to the rest of outlets in the circuit need to be attached to the screws labeled "line". To help manipulate the ends of the wires to fit around the screws properly you can use needle nose pliers to curl the wires clockwise so they catch easily when you tighten the screws.
5. Ground them outlets. If your electrician told you that your home's wiring has been grounded all you need to do to ground your newly wired outlet is to run a grounding wire from the green screw on your new outlet's mounting bracket to the grounding screw in your electrical box. Use an extended bit (3.5 inch is what we used) to get access to the grounding screw at the back of your electrical box. This added length will make it easier to tighten the screw.
6. What to do with an open ground. If you're house was built long, long ago and you're not sure if your wiring is grounded or an electrician tells you it's not, the easiest and safest thing to do is to install a GFCI (Ground Fault Circuit Interrupter). These are the outlets you often see near sinks in kitchens and bathrooms that have two buttons on them -- "reset" and "test". GFCI's will detect any change in current between the hot and neutral wires and will disconnect power if the levels aren't equal. To resume power you'll have to hit the "reset" button. Installing a GFCI is similar to a grounded outlet, but you can skip step 5, where you add a grounding wire to the back of the box. You will want to tape the sides of the mounting bracket (where the screws are) with electrical tape. This will prevent the screws from hitting the metal electrical box and tripping the GFCI.
7. Put everything back. Once you've moved all the wiring to the new outlet, reinstall it in the electrical box. We suggest you tighten each screw that goes from the bracket to the electrical box little by little, alternating between the two. Because electrical wires are so stiff, this will make it easier to get the bracket back on without leaving any screws cockeyed in the wall. Use a screwdriver to reattach the cover. Using a drill can cause you to over-screw, leading the outlet cover to break.
8. Test your work. Once you've reinstalled the outlet cover, head back to the circuit breaker and turn it on. Back at the outlet use an outlet tester to make sure everything's working correctly. The tester's coded lights will let you know if somethings' haywire with your installation.
Additional Notes: Don't install GFCIs into electrical boxes that power on refrigerators, garbage disposals, trash compactors, dishwashers, clothes washers and dryers, or home heating and cooling systems. These are known to often trip GFCIs and are often in areas that are hard to get to if you need to hit the reset -- don't want to have to pull out your dishwasher every time you need to reset the outlet.