Tips on earth Resistance Measurement and Improvement

Dear all hands

We know that grounding system is a crucial part in electrical safety system to avoid a man being shodked by electrical current. The main function of grounding system is to give a path for short circuit current and to give same ekuipotensial level in metal body or chase of electrical tool.

Before we decided what kind of grounding system that will we use , we must know the value of earth resistance in the location we will burry grounding rod. Earth resistance commonly determined by it soil type and compositon

Below is table of earth resistance on various soil type :

Table above just only average value of earth resistance, so we must conduct earth resistance measurement before installing gound rod. To conduct earth measurement we can use earth tester. Earth tester is now comerically available.

Earth tester for earth resistance measurement commonly equipped with 3 rod , below is the rod name for earth resistance measurement:

1. Potential rod
2. Voltage Rod
3. Reference rod

For more clear , figure below depicted an earth tester with rod for earth resistance measurement :

A is reference rod

B Is potential rod

C is current rod

For good earth resistance measurement, tree rod above is located with span 5 m each other . Ideally soil with good earth resistance has earth resistance below 5 ohm. And sometime we must conduct earth resistance improvement to meet our need.

To conduct earth resistance improvement with can add or pour salt material in our grounding rod hole but we must careful when chose salt material for earth resistance measurement because it can erode the ground rod. Usually for earth resistance improvement we can use salt from manganese .