Ground Rod Resistance Test

With this method the resistance of two electrodes in a series is measured by connecting the p1 and c1 terminals to the ground electrode under test.

Ground rod resistance test.

P2 and c2 connect to a separate all metallic grounding point like a water pipe or building steel. You can only do this by using the fall of potential method with a three terminal earth ground resistance tester. Check errant current flow to ground for operator safety and give an overview of ground system dynamics. Check your clamp on tester s manual if it uses another kind of configuration.

Multiple ground rods yield a lower resistance to ground than a single rod. If this is the case for your ground rod the best solution is to drive a different rod into a different location. Make sure that you have stripped back the insulation from both ends of the wire to allow for a good connection. Unfortunately there is not one standard ground resistance threshold recognized by all certifying agencies.

The nfpa and ieee recommend a ground resistance value of 5 ohms or less while the nec has stated to make sure that system impedance to ground is less than 5 ohms specified in nec 50 56. The lower it is the better job it does. For instance if a ground rod is driven into a very rocky and dry area it may not conduct electricity into the ground well. In areas where driving ground rods may be impractical the two point method can be used.

Step 5 measure the ground or leakage current if you wish to find out about the ground or leakage current all that you have to do is to set the rotary switch to ma or a. So if you are using 10 foot ground rods you must place. Ideally a ground should be zero ohms of resistance but. An ideal ground rod resistance should be below 3 ohms.

However we can estimate the resistance to ground using scenario b. Ground ring ground rods. Test the resistance of a single rod in a series or array. Step 1 connect your length of wire to a metal stake in the ground.

In some instances ground rods can be installed in areas where the earth has a lot of resistance. To properly test the resistance of a ges you must follow some simple rules. Simultaneously perform a bonding test of the grounding conductor necessary to complete the return path. Run the wire to your test location.

For a safe electrical system your ground rod resistance should have a very low resistance value. If your ground rods are placed at least one rod length apart you can use a formula to estimate the earth resistance of multiple grounding rods. Unfortunately as time goes by factors such as ground rod corrosion soil moisture high salt content high temperatures and loss of contact of your wires as well as others may increase the resistance of ground rod s hence affecting its effectiveness. For example the national electric code requires no greater than 25 ohms of resistance in a ground system.