Grounding is an essential safety mechanism that’s built into electrical systems to prevent equipment damage or injury. In an electrical circuit, the ground wire is an emergency path that allows excess current to safely travel to the ground instead of overloading the system or electrocuting the person interacting with it.
A common example of grounding that you’ve seen is an electrical cord with a three-prong plug. The circular third prong on this plug is the ground. The ground prong is inert, with no electricity flowing through it, except in the event of an electrical fault, in which case electricity would flow back through the ground, protecting the system.
How Does Electrical Grounding Work?
When an electrical circuit is functioning normally, electricity travels in a loop. The electricity enters your home, flows to an electrical outlet, and any unused electricity flows back out via the return path. In the event of an electrical fault, when the electricity can’t find a suitable path to travel, it will exit the circuit causing nearby conductive material to become electrified. This can result in fires, explosions, static electricity discharges, or electrocutions. To prevent dangerous emergencies such as these, all electrical systems must be properly grounded.
Imagine a wire inside your toaster becomes frayed or exposed. The exposed wire touches the inside of the toaster’s metal cover, and it becomes electrified. When you touch the toaster with your hand, the electrical current will pass through the toaster’s metal casing and into your body, giving you a painful shock.
The ground wire prevents this from happening by providing a low-resistance path for the electricity to flow out of the circuit instead of energizing nearby metal components.
In the case of grounding systems for a building, the grounding can be a path that sends the excess electricity into the ground where it dissipates. Inside an electrical device, the “ground” isn’t literally connected to the ground, it just provides a safe return path for the electricity to exit the circuit.
What is the Importance of Grounding?
Having proper electrical grounding is extremely important to avoid accidents and injuries, as well as ensuring continuous power to your facility. Lack of grounding can result in power outages, fires, damage to equipment and buildings, electrical shock, and even death.
The importance of grounding can’t be overstated. Make sure that your system receives regular professional inspections to verify that the grounding is properly installed.
How Do You Conduct a Grounding Test?
After grounding has been set up, it’s vital to test the system to make sure it’s functioning properly. It’s important to note that setting up an electrical system isn’t a simple “do-it-yourself” project. If you need to conduct ground testing for your business in California, contact the professional electrical engineers at MTA to safely and accurately perform these tests for you.
Ground Testing Methods
There are four types of ground testing methods: stakeless testing, soil resistivity testing, selective testing, and fall-of-potential testing.
Stakeless Testing
Stakeless testing is one of the quickest and most convenient ways to test for ground. It’s useful for testing at sites with hard or uneven surfaces like pavement, because the stakes don’t need to be driven into the earth. The drawback is that stakeless is less accurate than other ground testing methods. Stakeless testing uses two clamps that a current is sent between, and then the resistance is calculated.
Soil Resistivity Testing
Soil resistivity testing is an indirect method of testing the grounding of an electrical system. That’s because the focus is on measuring the soil’s ability to dissipate current, which impacts the grounding system’s performance. The testing process involves placing a clamp meter on the grounding conductor, and then driving several stakes in a straight line. Soil resistivity works by placing four probes into the earth, charging the first two, and then measuring the voltage drop when it arrives at the two further probes.
Fall-of-Potential Testing
Fall-of-potential testing (also referred to as ground resistance measuring or 3-pole testing) is a popular method for evaluating grounding performance. To begin this test, the grounding rod is removed from the electrical system. Then an electrode is placed into the soil, and a current is sent into the earth. Three electrodes are placed in a straight line, and they measure the voltage drop as it moves across the grounding system.
Selective Method Testing
Selective method testing allows you to measure specific parts of a grounding system, without the risks associated with removing the ground while testing. This allows the engineer to run a test without having to operate near an ungrounded system or inside an ungrounded structure. The selective method uses targeted testing, allowing engineers to troubleshoot system issues. After placing a clamp meter on the grounding conductor, the engineer will drive two stakes into the earth. The tester then sends a current through the grounding conductor from the clamp meter. Afterwards, the resistance is measured.
Grounding an Electrical Panel
Making sure an electrical panel is grounded is critical to avoid an electrical fault that could start a fire or electrocute someone. Grounding an electrical panel is a complex and dangerous process and should only be conducted by a qualified person. Extreme caution must be taken in this type of testing because, if done improperly, there is potential for the operator to be injured or killed during the grounding setup.
When conducted by a trained professional, grounding an electrical panel includes following the NEC guidelines (National Electric Code) which specifies the proper size and grounding type required for a given system. After installation, the grounding system needs to be tested immediately to ensure that it’s working properly.
How Often Should You Test a Ground System?
After set up and initial testing, aground system should be tested at least once per year. Typically, an annual test is sufficient, but some situations require more frequent ground testing. In locations with stringent regulations, or extreme seasonal weather changes, the ground testing should be performed more frequently, anywhere from once every five months, to once every nine months.
Contact MTA Electrical Engineers
If you need to have the grounding for your business set up or tested in California, contact MTA Electrical Engineers for a professional set up or annual inspection. Our highly-skilled team will conduct a thorough site inspection to determine if the grounding is functioning properly. We’ll provide you with the experience and expertise to ensure that your business is protected from electrical faults.