What Is a Ground Circuit?
This important safety feature protects you from an electric shock
Highlights
Grounding helps prevent serious shocks, electrical fires, and other problems.
Today’s homes are required by code to be grounded, but older homes may not be.
Most household grounding systems use grounding rods.
When your home’s electricity works properly, you probably don’t give it much thought. But if you understand the basics about how your house is wired, you’ll be better prepared to deal with any issues. One home electrical concept that’s worth familiarizing yourself with is grounding. A ground circuit ensures that the electrical circuit in a building safely completes if neutral wiring fails—without going right through your body to do it. If you’ve ever wondered, “What is a ground circuit, anyway?,” our guide will take you through how this vital feature works.
How Electrical Grounding Works
Broadly speaking, ground is simply a point in an electrical circuit where voltage is neutral compared to the electrical current in other parts of the system. In other words, ground is part of the circuit, but it’s not doing much by design, so it can act as an emergency circuit when necessary.
In a typical residential home, the grounding system takes the form of a third wire in addition to the live and neutral wires. This wire runs down to a rod that’s, well, in the ground. Take a look at modern outlet receptacles or light switches, and you can probably find a dedicated screw for that grounding wire.
The ground circuit exists specifically as a failsafe if something goes drastically wrong. Consider how lightning always connects along a path of least resistance to a tree, peak, or tall building. All electrical currents work on the same principle: They try to find the easiest way to get to the ground. If an electrical system needs to get rid of a huge amount of electricity quickly, the ground wire provides a safe pathway for the current. You might blow a fuse, but it’s a far better alternative than the current finding an exit point via flammable materials—or through a human body.
A ground circuit isn’t always necessary, but it's a vital feature when dealing with large amounts of electrical power. This includes the electrical circuits in our homes and vehicles.
Ground vs. Neutral
Ground and neutral wires have similar functions in a home’s electrical system, but some key differences exist.
The purpose of a neutral wire is to safely complete the electrical circuit to ground so the current flows properly. In that sense, a neutral wire is like a ground wire—except it’s always active. And because the neutral wire always carries a lot of current, it can overheat if damaged, possibly leading to shorts or other problems and dangerous shocks.
A ground wire functions separately and acts as a backup in case the neutral connection fails and the circuit needs to be completed by other means. In other words, it does the same job as the neutral wire, but only in emergencies.
Common Types of Ground Circuits
You can come across a few different types of grounding in electrical systems. But most residential homes usually use the following:
Grounding rods: Grounding rods are the most common method to ground home electrical systems. They are driven directly into the ground, and the primary ground line is attached to the top of the rod. These rods are standardized to be installed at least eight feet deep and are typically made of copper or copper-plated steel.
Grounding to water pipes: Some buildings are grounded with connections to water pipes that lead underground. This is no longer common—water pipe grounding is difficult to test and less reliable—but can still be found on some older buildings. Where water pipes are used to ground, they have additional requirements, including electrically continuous joints, at least ten feet of pipe directly contacting the earth, and avoiding water meters.
Is Your House Grounded?
The National Electric Code (NEC) and other standards typically require that household electrical systems include grounding. However, that wasn’t always the case, so not all older homes are grounded.
It’s easy to see if an electrical outlet was designed for grounding. Grounded receptacles have spaces for three-pronged plugs, with the third prong serving as the ground connection, while outlets without grounding will only support two-pronged plugs. You can also check light switches by unscrewing the faceplate and seeing if the receptacle has a terminal for a ground wire and if it’s attached.
If there are no grounding wires, your home may not have a grounding circuit available. This is usually only an issue in homes at least 60-70 years old. A licensed electrician near you can walk you through your options for electrical upgrades. Until then, adding GFCI (ground fault circuit interrupter) outlets can help provide valuable protection as well.
During electrical work, you may have to test an electrical system to find out if it’s grounded properly. A tool like a multimeter can show whether or not a system is successfully grounded. A hot wire will show low resistance if a multimeter’s probe is making a ground connection, meaning that the current is finding an easy way out.
Cost to Ground an Electrical System
Installing a home ground rod typically costs $100 to $300. However, grounding an old system also requires extensive wiring work and grounding wire can cost up to $8 per linear foot. This is why the total cost for a grounding project can easily climb to $4,000 or more.
DIY vs. Hiring a Pro
DIY electrical repairs can be dangerous, especially for those without proper training. Improper electrical repairs can create dangerous conditions in a home, such as an increased risk of electrocution and house fires. The National Fire Protection Association reports that wiring and equipment-related fires are the deadliest type of electrical home fire.
We recommend hiring a licensed electrician rather than attempting to ground your electrical system yourself. A trained professional will know the safety codes and requirements for your home and local area.
Frequently Asked Questions
Homeowners usually do not have to update existing systems unless they are doing significant renovations. Consult your local building codes or ask a knowledgeable local contractor for the details.
GFCI outlets help prevent dangers from ground faults that can cause shocks. This is a different issue that a ground circuit can’t fully address. It’s best to use GFCI outlets combined with ground circuits for complete protection for you and your electronics.
You can install a three-prong outlet without connecting any ground and plug in three-prong electronics into that outlet. The devices will function normally, but you won’t get any of the protection that grounding provides, so there’s an increased risk of serious problems if something goes wrong.