The grounding electrode in your electrical system connects all the pieces of that system to the earth. This setup draws unwanted voltages, like lightning strikes, safely away from your system. In order to design an effective electrode system, the soil resistivity of the ground must be properly measured.
Using the fall-of-potential method is a highly accurate way to test soil resistivity, and it has many benefits associated with it. Why should you use this method for your grounding electrode system?
How the Fall-of-Potential Method Works
When you hire a testing company to perform fall-of-potential ground testing, they will follow these steps:
- First, they disconnect the ground electrode in question from the system.
- Then, they connect their testing equipment to that ground electrode.
- For the three-point method, they place two stakes in the soil, about 20 meters from the electrode.
- The testing equipment generates a current between the electrode and the outer stake.
- The tester uses Ohm’s law (voltage = current x resistance) to calculate ground resistance.
Advantages of Fall-of-Potential Testing
There are a few different methods used by ground testing companies to measure soil resistivity, like the clamp-on method and the attached rod technique. The fall-of-potential method has a few advantages over these other tests.
High Levels of Accuracy
Because ground testers go through the steps described above several times during testing, the results are highly reliable. Fall-of-potential testing requires extra time and effort compared to other testing methods, but the work is worth it for those accurate results.
Flexibility in Test Site Size
While fall-of-potential testing often requires a great deal of space, it can be used to test electrical systems of any size. Fall-of-potential methods are remarkably versatile—there’s a reason this method has been in use since the 1900s!
Ease of Data Storage
The latest testing instruments used by ground testers allow all data to be stored either in internal memory or in a convenient mobile app. This technology is highly attractive to testing companies with a variety of different clients, as all those test results can be categorized and stored easily.
Why You Should Use Fall-of-Potential
We briefly mentioned some of the other ground testing methods available, like attached rod techniques and clamp-on testers, but the fall-of-potential method will give you the most detailed and reliable results for soil resistivity. The extra time your ground testers spend moving stakes and getting electrical readings will pay off in the long run.
If you need to test the resistivity of the ground around your electrical system, consider the advantages of using the fall-of-potential method to test that soil. Dreiym Engineering employs a dedicated team of ground testing experts who will take the time to get accurate measurements of your soil resistivity.
