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Tips & Tricks Blog


What is a Ground Wire, and Why Is It Important?

10/31/18

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You’ve heard the term “ground wire” and you know you have them installed in outlets around your home. But do you know what they do? The answer has major implications for household electrical safety.

What Does a Ground Wire Do?

As the name implies, a ground wire is an electrical wire that extends into the ground below your home. Electrical code requirements making ground wiring standard were phased in during the 1960s, so most modern homes have grounded outlets and electrical panels throughout. 

The purpose of a ground wire is to give excess electrical charges a safe place to go. The solid mass of earth below our feet has a negative electrical charge, which means positive electrical charges are naturally attracted to it. A ground wire helps those positive charges get to the ground in a safe, direct and controlled way, where they can be discharged without the risk of electrical shock or fire.

Shock Absorber

Excess electrical charges are common in any home. They’re the reason we safeguard our electronics with surge protectors, which means they include surges from things like lightning strikes and transformer malfunctions. But they also tend to occur several times per day, whenever large appliances start up; if you’ve ever noticed your lights briefly flickering when your air conditioner kicks on, that’s due to a minor surge of excess electricity.

In a properly grounded electrical system, that excess electricity goes directly into the ground. But if your home has electrical outlets that aren’t grounded, the surge could go in a number of dangerous ways.

The most dangerous way is if the electricity finds a path to the ground through a human body. This can happen if you touch an ungrounded plug or outlet at the wrong moment -- the electricity can travel between the part of your body touching the outlet and your feet on the floor, causing burns, nerve damage and even death, if the surge is powerful enough.

If the surge of electricity finds a path through the structural elements in your home, it can spark a fire. And there’s always the chance that the electricity will flow directly into appliances and electronics that are plugged into ungrounded outlets, which can damage them.

See For Yourself

There’s an easy way to check your outlets to see if they’re grounded or not. Grounded outlets have three slots, while ungrounded outlets only have two. The rounded, D-shaped slot is the one connected to the ground wire.

If you have a newer home, chances are good that you have a properly grounded system. In homes built in the early 1960s or earlier, there could be a combination of grounded and ungrounded outlets, depending on the electrical upgrades made over the years. Any DIY or substandard electrical work performed over the years could also mean there are weaknesses in your ground wire network.

The best way to know for sure is to schedule an electrical safety inspection with your local Mister Sparky. Our electricians can help you upgrade any ungrounded outlets as well.



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