It’s pretty uncommon to find two prong outlets in homes today. Builders now install three prong outlets, and most landlords have switched 2 prong to 3 prong outlets. Still, it may happen that you move into an older home with one or a few 2 prong outlets. If that’s the case you need to know how to ground an outlet or make the replacement. Here’s what you need to know and do for 2 prong plug replacement.


What Is a 3 Prong Plug?

A 3 prong plug is simply a plug with a ground. The two flat vertical prongs you’ll find on both 2 prong and 3 prong plugs: one is for the “hot’ wire, and the other is for the neutral to complete the circuit. The lower half-round prong is the ground. And the purpose of the ground is safety – chiefly to help reduce the likelihood of electrical shock (even fire) if something goes wrong.

3 Prong Outlet History

The National Electric Code (NEC), updated every three years, specifies electrical standards and is dedicated to safety and fire prevention. The NEC mandated 3 prong receptacles and plugs for the laundry only in 1947 and in 1956 expanded the requirement to include garages, basements, and outdoors. The 1962 edition required that all 120-volt receptacles and plugs in a home be three slot and three prong.

3 Prong Receptacle Design Benefits

The primary benefit of a 3 prong receptacle is that, in the case of some kind of short circuit, it helps prevent electrical shocks. With its third slot, a ground is provided that protects you from shock. When a short circuit occurs, a large amount of the current is directed back to the circuit breaker and then into the earth – instead of into you.

How to Wire a 3 Prong Plug

So if you’re wondering how to wire a 3 prong plug, it’s fairly simple really. On the inside of the plug, you’ll find three terminal screws: one brass colored, one silver, and a green grounding screw. Just attach the black (“hot”) wire to the brass screw, the white (“neutral”) wire the silver screw, and the green (sometimes bare) wire to the green screw.

What Is a 2 Prong Plug  

A 2 prong plug, as opposed to 3 prong plug, has, as the name indicates, only two prongs. What it doesn’t have is the third, lower prong for the ground wire. A 2 prong has only two flat prongs, one a little wider than the other for the neutral wire and the narrower one for the hot wire. It lacks the safety feature of the third prong. Without that third prong for grounding, the risk of appliance damage and even electrocution is increased.

Two Prong Outlet Background

When it comes to two prong outlet background, keep in mind that in the early stages of electrification, there simply weren’t any outlets. Electricity was used for lighting only, and that required just the wires, lights, and switches. In 1916 Hubbell patented the double-bladed, polarized plug, and around that same time Bryant figured out how to manufacture an inexpensive matching receptacle. And by the mid-1920s the two prong outlet and plug came into widespread use.

2 Prong to 3 Prong Outlet: Guide to Changing Outlets and How to Replace Them

Changing and replacing outlets – 2 prong to 3 prong outlet – can certainly be done, but it does take some preparation and know-how. If, however, you have any doubts or concerns, it’s always best not to risk a severe shock or injury and to call a qualified emergency electrician instead.

But if you still want to give it a go, here’s how to proceed . . .

  1. First, before you do anything else, turn off the power to the circuit you’re working on or even kill the main breaker to be doubly safe. And it doesn’t hurt to test the outlet before you begin work to make absolutely certain the power is off and that it’s safe.
  2. Remove the plastic outlet cover, usually a plastic plate with one screw in the middle holding it in place. Also, use a screwdriver (and other tools) with non-conductive handles.
  3. Remove the outlet from the outlet box and take the wires loose from he screws holding them in place, making sure to note where these wires attach to the outlet.
  4. Attach the wires to their proper places on the new outlet – black (hot wire) under the brass screw, white (neutral) wire under the silver screw, and bare or green wire (if you have one) under the green screw on the mounting bracket
  5. If you’re going from a 2 prong to a 3 prong outlet and your home has in fact been grounded, but there is no ground wire at the outlet, you will also need to run a wire from the green ground screw to the back of the metal outlet box for grounding the outlet.
  6. But if you live in an older home that isn’t grounded, you should be sure the new outlet you install is a ground fault circuit interrupter (GFCI) outlet.
  7. Next, insert the new outlet into the box, making sure the wires are pressed carefully into place such that a short can’t occur. Then anchor the outlet by screwing in the top and bottom screws, and replace and screw on the plate.
  8. You’re not finished yet. The last step is to test your work. Turn the power back on at the breaker box, and use a quality tester with coded lights to ensure that nothing has gone wrong during installation.

How to Add Ground Wires to Old Outlets

First off, simply sticking 3 prong outlet into the spot where the old 2 prong outlet was won’t gain you anything. You still need to know how to ground an outlet and how to add ground wires to old outlets.

You could, of course, rewire the circuit with modern wire and then install grounded 3 prong outlets. But for that you would need the services of a professional electrician for code compliance.

Ground wires can also be added to outlets on 15 or 20 amp circuits. This method calls for a bare or green (or green with yellow stripes) No. 12 copper wire to be run from the grounding terminal of the outlet to the grounding electrode at the beaker box. But, again, this is usually not a DIY project.

There is, however, an alternative solution . . .

How to Ground a 2 Prong Outlet

If you’re wondering how to ground a 2 prong outlet, the answer is that you can’t, really, because the outlet has no place to receive the ground wire. About your only recourse in such a situation is to install one of the new ground fault circuit interrupters (GFCIs). This won’t exactly ground a 2 prong outlet, but it will make it safer.

How to Ground a 3 Prong Outlet That’s Not Grounded (Or How to Ground an Outlet Without a Ground Wire)

It is possible, though, to ground a 3 prong outlet that’s not grounded – that is, to ground an outlet without a ground wire. Here’s what you need to do.

You just need to establish a continuous electrical path back to the breaker panel. And if the outlet is installed in a metal outlet box with metal conduit traveling back to the panel you can likely do that. You have to connect a bare copper wire to the ground screw on the outlet and then attach it to the metal outlet box. The metal conduit, which connects to the outlet box, then serves to provide the pathway back to panel, thus grounding the 3 prong outlet with the materials already in places

Why Should You Replace an Outlet Without Ground?

As we’ve mentioned, all outlets have a hot wire and a neutral wire, and modern outlets have a third wire, the ground wire. And this ground wire is an important safety feature.

If your home or even an individual outlet experiences a short or surge of excess electricity, the ground wire bleeds it off back to the main panel and then into the earth (hence the name “ground” wire). This bleeding off, then, greatly reduces the risk of fire, shock, or electrocution. Basically, the purpose of replacing an outlet without a ground is to protect your appliances, your home, you, and your family.

How to Replace a Two Prong Plug

The process of how to replace a two prong plug is very simple and easy because you have only two wires and two prongs to deal with. You just have to make sure you connect the hot (usually black) wire the correct side, which is the one with the narrower flat blade. And then you connect the neutral (usually white) wire to the appropriate place for the neutral side, the wider of the two blades.

What Is a 2 Prong Surge Protector?

Before answering the question “What is a 2 prong surge protector?” we need to be clear about exactly what a surge protector is and what it does. The job of a surge protector is protect your delicate electronic devices from power surges. A power surge, also known as a transient voltage, is an increase in voltage markedly above the standard household norm of 120 volts. Such a surge can inflict significant damage on unprotected electronic devices owing to the resultant heat increases.

A surge protector protects your electronic device in two ways. When there is a surge, it blocks some of the extra voltage, thus protecting your devices. Or it shorts to ground excessive voltage above the critical threshold. Remember, too, that the “joules” rating is the most important consideration in choosing a surge protector

Now, there really is no such animal as a 2 prong surge protector. This is just a shorthand way of talking about using a surge protector with 2 prong plugs or 2 prong outlets. With a 2 prong outlet, the purpose of a surge protector is somewhat defeated. It does, however, still provide some internal surge protection with its voltage-blocking capabilities.

When Do You Need a 2 Prong to 3 Prong Surge Protector?

The answer to the question “When Do You Need a 2 Prong to 3 Prong Surge Protector?” is . . . always. Your surge protector must have a three-prong plug so that there is a ground for diverting the excess voltage from the surge. And this also means that you should avoid using a 3 prong to 2 prong adapter on your surge protector cord to plug it into a 2 prong outlet. You just shouldn’t take that chance with your expensive electronics

Is Knowing How to Ground an Outlet Enough?

So if you know how to ground an outlet or replace a 2 prong plug, can you safely do it? Maybe. The real question is: Should you do it? Probably not. Besides the safety factor and hazards involved, there are many municipal code considerations to take into account. And there’s also your home owner’s insurance to consider. If you perform this electrical work yourself and then have a fire, will you still be covered? Depending on the circumstances, you may not be.

An electrical problem involving an ungrounded or unsafe outlet is not something you should ignore and, in some cases, it is not something you should attempt to fix yourself. Besides being a major inconvenience, there is a chance of shock or electrocution, as well as a marked fire hazard that can quickly develop into an emergency situation. What you need, then, is an emergency electrician to keep your appliances and electronic devices operating and to keep you and your family safe. So if you do encounter problems with outlets or plugs, call the experienced electricians on call 24/7 at Work Best Electric.

Don’t take a chance by waiting or attempting it yourself if you’re even the least bit uncertain about how to proceed. We can help you prevent an electrical problem from escalating into a life-threatening emergency. We employ only the best, most qualified professionals and use state-of-the-art equipment to provide high-quality service and a safe home. To be connected with a qualified local electrician, contact us today.