The Secret Reason Why Outlets Have Three Prongs

That third prong? It's there for your safety.

The Secret Reason Why Outlets Have Three Prongs

That third prong? It's there for your safety.

From when you get out your blow-dryer in the morning to when you go to charge your phone at night, odds are you’re plugging something into an outlet ten or fifteen times a day. However, you probably don’t pay much mind to the purpose of the three holes you’re plugging that device into.

If you look at an outlet, you’ll notice three distinct components: two vertical slits and a round hole slightly below or above their midpoint. So, what’s the purpose of these three distinct parts of a plug?

The smaller vertical slit in an outlet is known as the “hot” side, into which electricity flows into the plug. The electricity then flows from the hot side, to the larger, or “neutral,” slit in the outlet in the case of a direct current (DC) system. In the case of an alternating current (AC) system, it changes direction periodically.

You might be asking yourself why there’s a third section on the outlet if the current is already flowing back and forth between the hot and neutral sides alone. This is where the ground prong comes in. The ground prong—the part of your plug that goes into the round hole in your outlet—is primarily there for your safety. The ground prong delivers excess electricity that might have escaped the circuit, like in the case of a loose or uninsulated wire, to the ground.

If, for instance, a wire came loose in your metal-encased appliance and touched its exterior, the device would become electrified. If you were to then touch the appliance’s exterior, the electricity could then flow into you, shocking or potentially killing you. However, the ground wire ensures that any errant electrical charges are being sent to ground, a non-conductive destination where they won’t cause harm.

So, why is it that some electronic devices still only use two prongs? Devices with only two prongs tend to fall into two categories: they’re old or they have sufficient insulation and a non-conductive exterior (i.e. a plastic outer shell instead of a metal one) so that you’re unlikely to be electrocuted even if there’s a malfunction. Fortunately, appliances with ground plugs aren’t the only way to protect yourself: the 15 Best Ways to Protect Your Home will keep your whole family safer.

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