⚡ FREE CLASS: How to Do a Complete Electrical Installation from Scratch, Easily, Even if You Are Not a Professional Electrician: ➽ https://eletr.co/aula?utm_content=gB6... -------------------------- ???? FAAALA ENGEHALL COMMUNITY ???? Join our community on WhatsApp to receive valuable tips and news in the electrical area, important information and much more. ???? ➽ https://eletr.co/fala-eng -------------------------- Did you like this video? ???? ✔️ Leave your comment and share with your friends ✔️ Follow our networks ➽ https://eletr.co/links?utm_content=gB... -------------------------- ???? NR10 Course with 20% discount ➽ https://eletr.co/nr10?utm_content=gB6... Is it possible to measure GROUNDING RESISTANCE without a TERROMETER? Hey my dears!! Welcome to another WHAT'S THE QUESTION from Engehall! Electrical grounding is one of the topics that leads the ranking of questions on Engehall's social networks! And look at this question: "André, can I measure grounding resistance without using a ground tester?" I only have a multimeter and I've seen a video teaching how to do it this way. So, is it possible, is it safe and reliable? Since we have both a multimeter and a ground tester, we decided to compare them in practice... Guys, I've said this in several videos, but it's always good to remember. The electrical grounding of an installation is nothing more than connecting the equipment to the ground, so that leakage charges from the system can be drained. In this way, users of a building are protected against accidental electric shocks due to faults or conditions that are different from normal working conditions. And until recently, many professionals still claimed that the ground resistance of a grounding system should be 10 ohms, but get that out of your head, my dear. Since 2015, after the revision of NBR 5419, the guideline has been that we should always look for the lowest value, as close to zero as possible. And to measure this ground resistance value, we use a piece of equipment called a ground tester. Here on the channel, we have several videos showing how to use this equipment. Now, is it possible to measure this resistance value without having a ground tester? The answer is… Theoretically YES, in practice MAYBE. It is possible to check the resistance of the soil without using a TERROMETER, but it is more work and for that we will need to apply the famous OHM'S LAW. In other words, to find the resistance, we will need the voltage and current values. Look at the experiment; We have a TT grounding rod exclusively for our electric fence, which will be ideal for this experiment, since it is not interconnected to our system. First, we will measure the voltage between the network phase and our grounding rod. Then, we will connect the phase to this rod and check the current that will pass to the ground. Then, we just need to substitute the values ​​we found in the formula and we will have the resistance value. However, we need a parameter to know if the value that will be found in the test will be close to the real value, and for that, we will first test the resistance of our rod using our TERROMETER. We have our TERROMETER already installed here, and we will see what the resistance value will be that it will show us. Well, let's wait for it to stabilize a little. Notice that it shows us that the resistance is a little above 48 ohms. This will be our reference value! Now using a multimeter, we will connect one end to our grounding rod and the other end to our phase and see what value it will show us. See that the voltage found was 129.0 volts. Now we need to see what the current will be when we connect the phase directly to this rod. The current value found was 1.67 amps. Substituting the voltage and current values ​​into our formula, we have that resistance is equal to voltage, in this case 129.6 volts divided by 1.67 amps, which gives us a resistance value of 77.6 ohms. Well, it is a very different value from what we found using the THERMOMETER, do you agree? But why did this difference in value occur? This may have been caused by the way the thermometer measures, which uses 2 rods as a reference. In this way, when the earth tester “injects” a voltage to the ground, the device “analyzes” the voltage drop between these rods and the grounding rod and shows us the resistance of the ground, according to its calibration. The multimeter also works in a similar way, but in the voltage and current scale used, it is not injecting voltage, it is simply “taking advantage” of the network itself to give us a value. For this reason, it is not the right equipment and it is important to have calibrated equipment, to provide us with the most accurate values ​​possible.