Today we’re going to talk about power outlets, grounding, and how you can safely plug things into an old 2-prong outlet by replacing it with a GFCI or “ground fault circuit interrupter” receptacle.
If you live in an older North American home (specifically one built before the mid-1970s) you have probably known the frustration of having a 3-prong plug and only 2-prong outlets. As such, you are probably familiar with this dude:
Commonly called a “cheater plug,” these little adapters allow you to plug your laptop or PC into the million-year-old electrical wiring in your home. In theory, the little tab at the bottom screws onto the faceplate to ground the outlet. In practice, almost no one actually screws the thing in place (naughty!). Even if they do, in many homes that isn’t enough to provide a connection to ground. If something causes a short the electricity will use YOU for grounding. In other words: ZAP.
Another common problem in older houses is when someone “helpfully” installs a three-prong outlet but doesn’t bother grounding it. This is much worse than using a cheater plug because those who use it will be unaware that the circuit isn’t grounded. You can test for this using an inexpensive circuit tester available from any home improvement store.
If you want to do things right, you can hire an electrician to rewire and ground all your circuits. In my area, the quote for this was $300 per outlet — way out of budget for me, given that the entire second floor of our home was ungrounded.
If you’re feeling handy, you can replace a 2 prong outlet with ground fault circuit interrupter (GFI) receptacles. These work by immediately cutting the power if they detect a sudden change in current flow (perhaps caused by your body suddenly having electricity flow through it). It’s not a perfect solution — it won’t keep a power surge from frying your electronics — but it adds a layer of safety and convenience.
Doing electrical work can be intimidating, but if you follow the directions and use common sense, this one is actually pretty easy. As always with home improvement, stop and call a professional if there is something you don’t understand or if at any point you don’t feel confident proceeding. If you take off your outlet cover and think “wow, this looks nothing like the instructions say it will,” stop and call a professional.
Old houses often have really questionable wiring. If anything is nonstandard, it’s important to have an electrician look over the whole system.
Stuff you’ll need:
- GFCI outlet in the color of your choice
- Wire nuts
- Non-contact voltage tester (optional but super handy)
- Screwdrivers, including one small flathead
Step 1: Turn off power to the old receptacle
First cut the power to the receptacle. Do this at your breaker box and put a piece of tape over it while you’re working so no one turns it back on. Verify the power is off, preferably with a non-contact voltage tester. Always check to make sure the receptacle is off as electrical boxes are often mislabeled.
If you’re not sure which breaker goes to the outlet in question, you can stick your voltage tester in the outlet and start throwing switches until the beeping stops. Warn your housemates before you do this and label the breaker when you find it.
Step 2: Disconnect ONE outlet
Usually the outlets in a room are all on the same circuit. When you have two outlets in one receptacle (like most do) you need to figure out which comes first in the circuit. This is referred to as “line” for the incoming connection and “load” for the outgoing connection.
While the order doesn’t matter for normal outlets, it’s important when you’re installing a GFCI. If the GFCI is installed backwards, it won’t protect you (and as a safety feature, modern GFCIs won’t work at all).
In order to figure out which is which, we’ll disconnect one of the old outlets. Leave the other one connected. Use the wire nuts to cap off the disconnected wires and carefully push everything back into place.
There are a few different styles of outlet, but most of them have a tiny slot you shove a screwdriver in to release each wire. If your outlet is particularly old it can take some fiddling to get the wire out.
Step 3: Test remaining outlet
Replace the outlet and cover and turn the power back on. Test the outlet that’s still connected. If there’s power to it, this means it is line. If it’s dead, it’s load. Cut the power again and open the receptacle back up.
Step 4: Connect the new GFCI outlet
Following the instructions that came with your outlet, connect the line and load wires to the appropriate spots on the outlet. Carefully place everything back in the wall and replace the faceplate.
Step 5: Test the new GFCI outlet
Turn the power back on and test the outlet. First press the reset button. There should be power flowing to the outlet. Then press the test button. The outlet should go dead. If it does, congratulations, you’re all done! If it doesn’t work correctly turn off the power and check your wiring again.
If it’s wired correctly and still not working, then it’s time to call a professional for help.