Megger has produced electrical testing equipment for over a century. The company is known for its insulation testers. These devices, commonly referred to as "Meggers," are used to test grounding systems, which includes the insulation of wires between conductors on circuit boards and the insulation in ground wires. Testing these systems can prevent electric outages or damage by preventing electrical surges. Properly functioning grounding systems can also protect against lightning strikes that could short electrical systems. A Megger will ensure that the ground wires are in good condition to prevent electricity from misdirection.
Connect two ground testers to the grounding cable, which is connected to the grounding rod(s). Clamp the testers on to the cables using the metal clamps on the end of each cable. One tester measures current while the other measures voltage. Ground testers will test the performance capabilities and safety of the cables used to protect a device against electric shock and surges.
Set the Megger to about 160 turns per second by turning the numbered knob on the its face until the arrow is aligned with the "160" line on the Megger. "Turns per second" refers to the number of rotations the wheel inside of the Megger will make within a second. This wheel acts as an electric generator that will test a wire's insulation.
Look on the Megger screen to find the ground loop resistance. If there is more than one rod connected to the grounding cable, multiply this number by the number of watts in the reading to determine the total ground loop resistance for the system.
Clamp the two terminals of the Megger to the two bus tangs of the circuit board using the small clamps on the ends of the terminals. The tangs are at the end of the bus lines and act as connection ports for other devices.
Turn the Megger to 160 turns per second as in the previous section.
Read the result on the screen of the Megger.
Clamp both Megger wires to the circuit board with the attached small clamps. The wires can be connected to any part of the perimeter of the board.
Measure from the metal conduit on the circuit board to each of the two wires.
Set the Megger to 160 turns per second. Turn the knob on the face of the Megger until the arrow on the knob aligns with the 160 line on the face of the Megger.
Read the result on the screen of the Megger. The result will be displayed on the digital screen of the Megger. You will be able to choose which measurement you will need (ex: wattage).
Unplug the device you are testing.
Clamp one terminal wire of the Megger to the circuit board and the other to a stake in the ground. Use the small clamps on the end of each wire to connect them to the perimeter of the circuit board at any point and to the stake in the ground. The stake will have to be small enough to fit in the clamp of the Megger.
Set the Megger to 160 turns per second. Turn the knob on the face of the Megger until the arrow on the knob is aligned with the 160 line on the face of the Megger.
Read the results on the digital screen of the measure. This measurement will display the amount of electricity that the insulation of the wire can handle.