The Difference Between 2- and 3-Pin Electrical Plugs (and Why It Matters)

Unless you live in an old house with two-prong outlets, you probably don’t pay much attention to plugging and unplugging electronic devices and appliances.

But at some point, you’ve probably noticed that some plugs have two pins while others have three, and you may even have wondered why that is and what the difference is between the two. Probably no. Either way, here’s what you need to know.

Two-prong sockets vs. three-prong sockets

Before moving on to sockets, let’s start with sockets. Sockets with two pins were introduced in 1962 , but not everyone immediately switched to them: it is not unusual to find them in some houses built in the late 1960s and even in the 1970s and 1971.

After that, three-prong sockets became the norm and remain so to this day, although as you can see in the graph below, they have become more sophisticated over the years, offering additional security measures.

Now let’s talk about holes. Both two- and three-pin sockets have two parallel vertical holes :

• The narrow opening on the right (i.e., the “hot” slot) provides access to the hot wire.
• The wider hole on the left (i.e. the “neutral” slot) is for the neutral wire.

Three-prong sockets also have a third hole below the slots (i.e. “ground”) that connects to the ground wire.

We will pass this on to the professionals at Shockley Electric to explain what happens next:

When you plug a two-prong device into a wall outlet, power flows from your home’s electrical panel through the hot plug to your device (powering it in the process) and back to the neutral pin, which sends electricity back to the switch. box and closes the circuit.

At least that’s how it should work.

Why three prongs are safer than two

Let’s say there’s an unexpected surge of electrical current (more than 120 volts, which is what most outlets are designed for), or a loose wire inside the appliance comes into contact with its metal case.

The current has to go somewhere, so it passes through the device, possibly damaging or destroying its electrical components, and enters your body, which can result in a serious electric shock. Current can also enter the structure itself and cause a fire .

But this won’t happen with a three-prong outlet because excess electrical current will be directed back to the main electrical panel (which must be grounded) and not to the user or home. Or, if it’s a three-prong ground fault circuit breaker (GFCI) outlet – the kind of push button found in bathrooms – the switch will detect it and immediately cut off power to the outlet.

Why don’t all new household appliances and electronic devices have three-prong plugs?

Given that three-prong plugs are considered safer, you might be wondering why, 60 years after three-prong sockets were introduced, some new household appliances use two-prong plugs.

In short, two-prong plugs are cheaper to manufacture , so manufacturers will use them whenever they can and still meet the standards of independent safety testing organizations such as Underwriters Laboratories (UL).

Since 1969, three-prong plugs have been required for mainstream electrical appliances, but two-prong plugs are still used in “double insulated” appliances, which have two levels of insulating materials between their electrical components and external surfaces people touch. This provides protection against fire and electric shock even without a grounding prong.

Can I use an adapter to connect a three-prong plug to a two-prong socket?

Technically yes, it works, but it’s not considered safe. Commonly referred to as “rogue plugs”, “rogue plugs”, or “pigtail adapters”, they can be a convenient workaround, but when used in an outlet without a dedicated ground connection, these adapters provide no protection against fire, electric shock, or damage. to the connected device.

And it should be taken for granted, but don’t cut the third pin off the plug so it can fit into a two-prong outlet. Again, even if this allows you to turn on the device, you are putting yourself, your home, and the device at risk.

Does this mean that you need to redo the wiring in the house, or at least in part of it? Although this is the most permanent solution, it is not available to everyone. At this point, your best bet is to consult with a licensed electrician to learn about your options, and go from there.