Updated: Nov 23, 2020
Hello, restorers! This month, I thought I’d try something just a bit different, because I get a lot of questions about this topic — what should be done with old electric outlets? Well, first of all, let me give the usual blah, blah, blah disclaimers. I’m not a professional, licensed electrician, so what you do is up to you to decide. Your level of comfort, your skills, and your knowledge of electricity should dictate whether you do anything on your own or hire an electrician. What we’ll embark on in this particular journey is quite simple and basic, however.
The issue is that most old house outlets have two “prong holes” in each receptacle, often of equal size. Many things we want to plug in today have three prongs, two flat ones plus a third, differently-shaped one. Some plugs have 2 flat prongs, but one is larger than the other. Here are some typical old house outlets:
Here’s what we might want to plug into it:
You can go to most any “dollar store” and buy an adapter that will allow you to eliminate the third prong (gee — why is it there if you can eliminate it?) but even these have one prong larger than the other, and may not fit in the old outlet. Many people, including me, have “in a pinch” ground down the larger prong to allow it to fit into the outlet. Shame on all of us!
The way it’s supposed to work is that the smaller of the flat prongs (and the smaller of the flat outlet holes) is the location of the “hot” wire, the current-carrying side of things. It’s smaller to help prevent the accidental insertion of foreign items. (Give a child a screwdriver and he/she will poke it into the most unusual places!) The larger flat prong and hole is the “common”, often thought of as the “return path” of the electricity after the light, motor, or other appliance uses it. This is called a “polarized” outlet. Power should go from the outlet to the on/off switch of the appliance, then through the appliance back to the outlet, because you can only plug the appliance in one way. With both prongs of equal size, the appliance will work fine but be much more dangerous since power can go from the outlet through the appliance, THEN to the on/off switch, and back to the outlet, depending on which way the plug is turned when inserted. You could be holding an appliance in your hand that has electricity throughout it (but not running since the switch is off), and easily get shocked or worse if you touch some energized part.
The third prong/outlet hole is the “ground”, or “earth” as they say in many parts of the world. This should be the “path of least resistance” should there be a short-circuit in the appliance. This means that electricity should go “to ground” more easily than through your body. If you’re holding something that’s shorted, it’s more likely that you’ll blow a fuse or pop the circuit breaker than get electrocuted. Eliminating the ground with one of those adapters takes away that level of protection. It should be noted here, though, that many things now, including tools with plastic housings, are “double insulated” in their manufacture, and only need 2 prongs instead of 3.
OK, that’s the issue in a nutshell. So, what do we do with old outlets so that 3-prong items can safely be plugged in?
Let’s first realize that many old houses have old wiring. Old wiring can be in several forms, but most people think of “knob and tube” wiring in old houses. (Actually, knob-and-tube is quite safe when in good original condition because there’s a considerable distance between the wires.) However, after many years of use and abuse (like hanging things from the exposed wires) the absolute best thing is to replace that wiring, usually 2-conductor, with modern 3-conductor wiring of the appropriate gauge. That’s probably more than I want to get into with the do-it-yourself crowd, so hire an electrician. If your goal is as originally stated, to update a few outlets, read on.
Another thing to get out of the way right away is that you SHOULD NOT simply remove an old 2-prong outlet and replace it with a 3-prong one. Again, it will WORK, but to an observer, it will appear that it’s a proper, grounded outlet, when it’s not. This is actually against the electrical code, and a house inspector, for example, will require this be corrected should you ever go to sell the house. The proper, safe, and legal way to get around all this is to install a “ground fault interrupter” type outlet. The down side is that (to my knowledge) no one makes one that looks old or original, so it will likely mar the appearance of a true historic restoration. (Hmmm. There could be a market there for someone to design such a thing…) Another down side is that instead of $1 for an outlet at your local hardware store, you’ll probably pay about $15-$20 for the outlet. GFIs, or GFCIs, as they are also called, work by very quickly shutting off the outlet if it detects something funky going on, like current heading to the ground side when it shouldn’t. Even though hooking up a GFCI (3 wires) to old house wiring (2 wires) seems wrong, it isn’t, and is an acceptable solution to our dilemma. While the outlet (and a plugged-in appliance) won’t truly BE grounded, the GFCI will treat it the same, and shut off when it detects a grounding issue.
OK, so now what? You’ve decided to do the right thing, and install a GFCI outlet. What’s next? You need to plan what type of outlet to buy. Again, current codes want outlets to be tamper-resistant, meaning there are plastic shields somewhat covering the prong holes, and it takes a good deal of effort to push an appliance plug past them to insert it. (Again, this makes it less likely that a child will insert something that shouldn’t be.) You can also buy regular outlets that are TR, so consider that when updating your more modern grounded outlets.
Here’s a picture of a common TR GFCI outlet:
The second consideration is the power rating, normally 15 amperes or 20 amperes, or simply 15A or 20A. 20A outlets are used where power consumption is greatest, like on a kitchen counter, while the 15A outlet is at home on a wall for a table lamp. The outlet rating should match the wiring, however! Installing a 20A outlet does not mean there are 20 amperes of power there. A 20A outlet would normally be installed on wiring of 12 gauge, while a 15A outlet is typical on 14 gauge wiring. It’s the size of the wiring and the breaker on that circuit that determines the available power.
Well, we’re finally getting to the actual install! First, turn off the power to the outlet by removing the fuse, or tripping the circuit breaker. In the old days, I’d plug a radio into the outlet, then flip breakers until I no longer hear the radio, to determine the circuit. Now I use a “circuit detective”, a very inexpensive 2-part device that I like a lot. One part plugs into the outlet, and with the other, you “scan” the breaker panel until it signals that you have found the right circuit. (An aside: You should “map” your whole house so that you know everything that is on every circuit — more on that another time.)
With the circuit off, you can safely remove the outlet cover, the screws holding it in place, and then gently pull the outlet out of the wall box. Most old outlets were installed long before the invention of quick “push-in” type connections (which I hate!), so all you need to do is undo the screws holding the wires and slip them off. (Remember, lefty-loosey, righty-tighty…) If you do have the push-in connections, it’s probably easier to cut the wires and re-strip the end bare, assuming there’s enough slack to do so.
Look at the directions on the new unit for how to attach the wires. While the tried-and-true method is to wrap the wire around the screw, some outlets now have a small “plate” with grippers under the screw heads, and all you do is insert a straight wire end under the plate, then tighten down the screw. If you’re attaching with the screw method, be sure to curve/wrap the wire end clockwise around each screw so that it is held and pulled tight when the screw is snugged tightly down. Remember to put the correct wires on the correct screws — white to the silver, larger prong side, black to the brass, smaller prong side. You won’t have the extra ground connection, so just tighten that screw down, along with the other set of wire connections if they are unused. If you like to be super-safe (and this is required in some areas), you can wrap the entire mechanism with a couple turns of electrical tape just to be sure that nothing touches what it shouldn’t when reinstalled. The new GFCI is a lot larger than the old outlet, and hopefully there’s enough room in the old wall box for you to tuck the wires back in and still fit the outlet in without it rubbing against anything.
Put it all in place, including the new cover, turn on the power to that circuit, and give the GFCI a test or two. It will have “test” and “reset” buttons just for that purpose. Then, test it once in a while as it’s being used to be sure power gets shut off immediately when the test button is depressed, and comes back on with the reset. You’re done, safe, and legal!
I hope all your projects go well. Thanks for reading, and happy restoring!