1. © 2007 Ideal Industries www.idealindustries.com 1 of 12 Basics Clamp-on Ground Resistance Tester

2. © 2007 Ideal Industries www.idealindustries.com 2 of 12 Basics Clamp-on Ground Resistance Tester Integrity of the Ground Three key components of the single ground Electrode –Resistance between Ground Electrode and Clamp, Bonding in multi- rod applications –Resistance of contact between soil and rod(s) –Resistance of Concentric Shells of earth

3. © 2007 Ideal Industries www.idealindustries.com 3 of 12 Basics Clamp-on Ground Resistance Tester Integrity of the Ground Effect of the Soil on Electrode resistance –Soil conditions, and soil types Sandy soil have higher resistance that clay or loam –Seasonal Environmental conditions which effect both moisture and temperature

4. © 2007 Ideal Industries www.idealindustries.com 4 of 12 Basics Clamp-on Ground Resistance Tester Integrity of the Ground Ground Electrode –Typically measured only at installation In truth very seldom tested by installers. Only one out of 10 said they test single point ground Electrodes, in an informal survey –Methods of testing the ground electrode Fall potential test, and Slope method Ground resistance clamps

5. © 2007 Ideal Industries www.idealindustries.com 5 of 12 Basics Clamp-on Ground Resistance Tester Test Equipment Clamp-On Ground resistance tester. The Resistance of the total ground network is now measured. This is a loop tester and requires the utility return to act in simples terms as the aux rods.

6. © 2007 Ideal Industries www.idealindustries.com 6 of 12 Basics Clamp-on Ground Resistance Tester Test Equipment Clamp-On Ground resistance tester. Make sure you have a clean, clear connection of the clamp around the ground. Select and measure the current, if current is > 5 (this my very from manufacture) resistance can’t be measured using the ground clamp tester.

7. © 2007 Ideal Industries www.idealindustries.com 7 of 12 Basics Clamp-on Ground Resistance Tester Test Equipment Clamp-On Ground resistance tester. If voltage (E) is applied to any measured grounding probe R(X) through a special transformer, current (I) flows through the circuit and can be measured, thereby establishing an equation which can be used to calculate R(x) –E/I=RX. If E is kept constant, then through the use of a CT current can be detected and the resistance of the ground electrode circuit my be achieved.

8. © 2007 Ideal Industries www.idealindustries.com 8 of 12 Basics Clamp-on Ground Resistance Tester Clamp-On Ground Resistance Measurement R1, R2, ---Rn can be considered as a large parallel resistive circuit. As we know, a large number of resistors in parallel with each other effectively create a resistance value which is lower than the value of the least resistive path. –Here is an easy to understand example of parallel resistance. –Simple equation, 1/R = 1/R 1 + 1/R 2 + 1/R 3 + 1/R 4. –If R 1 =3.5, R 2 =4, R 3 = 4.5 and R 4 = 5, –then 1/R=0.285 +0.25 + 0.22 + 0.2, or R= 1.04 ohms.

9. © 2007 Ideal Industries www.idealindustries.com 9 of 12 Basics Clamp-on Ground Resistance Tester Clamp-On Ground Resistance Test Advantage is that the ground electrode doesn’t need to be disconnected from the electrical system. The jaws of the clamp must be placed in the electrical path of the systems grounding wire to the ground rod

10. © 2007 Ideal Industries www.idealindustries.com 10 of 12 Basics Clamp-on Ground Resistance Tester Clamp-On Ground Resistance Test This is an example the Clamp-On Ground tester is being used to measure the ground resistance in a street light application Note in this application the tester is place between the ground conductor and the ground electrode. The loop is between the ground conductor and the parallel path of R 1, R 2 ---R n back through the earth resistance.

11. © 2007 Ideal Industries www.idealindustries.com 11 of 12 Basics Clamp-on Ground Resistance Tester Earth Testers Ideal/Megger 61-788 –3 pole Testers IDEAL/Megger 61-789 –4 pole Testers –Self powered - no need for hand crank –Low power consumption Compact and lightweight –Quick battery check –Limited lifetime warranty

12. © 2007 Ideal Industries www.idealindustries.com 12 of 12 Basics Clamp-on Ground Resistance Tester Earth Testers Ideal 61-920 Ground resistance Clamp –Ground Resistance –Ground Leakage Current –Auto ranging –Audible indication < 40 ohms –Open jaw indication –Data hold