If you live in the United States, you’re likely well-familiar with our typical wall-socket setup. Your plug has two flat pieces of metal roughly half of an inch wide, with one side sometimes being slightly wider than the other. Your wall socket has two slots that match this, with one side also being slightly larger than the other. However, sometimes there’s a variance: some plugs have a third prong below and between the normal two, and most electrical sockets also have a third hole to match this plug. What’s the difference between these two types of plugs and is one better than the other?

To put it simply, yes, one is better than the other. When it comes to electrical plugs, the old adage “less is more” does not apply—the three-prong plug is far better than a two-prong. To learn why, let’s discuss the difference between the two.

In order for electricity to flow, you must complete a circuit. A circuit essentially is a connection from your power source to the device, and then from the device back to the power source. The line that brings power from the power source to the device is called your “hot wire”, which is most often red and comes off the positive terminal (noted by the large “+” sign). The line that then returns from the device to the terminal, usually a black wire connected to a “-“ sign, is known as the “neutral wire.” A plug must have both of these lines in order to work.

However, the third prong in a three-prong plug is a “ground” plug, which dramatically improves safety. When an unexpected burst of electricity happens, such a short in the device or a surge from your power supply, the ground plug will take that abundance of additional electricity and move it away from the device and down into the ground where it is safe. This prevents your device from being overloaded which can cause overheating, sparking, and fires in addition to ruining it.

Three-prong plugs didn’t become the standard in homes in North America until the late 1960s. If you have a home that was constructed around this time or after, odds are your wall sockets are probably already of the three-prong variety. Two-prong plugs can work with three-prong sockets just fine, and you’ll rarely experience any issues.

However, if you have any old two-prong plugs, you’ll likely need your electrical system updated in order to upgrade to a three-prong setup. Properly installing ground wires can involve several hours of electrical work and even cutting into your walls in order to do so properly, so it’s a rather large undertaking. However, it’s by far the safest and most prudent option.

Another option that doesn’t involve tearing open your walls is to install a ground fault circuit interrupter outlet, otherwise known as a GFCI. These sockets are two-pronged, but feature a miniature circuit breaker that measures the resistance through a plug and mechanically shuts off when the risk of a shock is present. While this can help you avoid being shocked by a faulty device, there is still no ground wire present so your electronics are not protected from a power surge.

How many times have you observed your neighbor using a weed-whacker that is connected to a series of four or five extension cords in order to reach the far corner of the yard? Probably plenty of times. When using a series of cords, be sure they are all the same rating, and check with the manufacturer or your local licensed electrical contractor to see if it is safe.

Extension cords are rated by the thickness of the wires inside using a standard known as AWG (American Wire Gauge).