Grounding of electrical installation is primarily concern with ensuring safety. The main purpose of grounding is to channel the fault current straightly to earth. To produce a good grounding system, the value of earth resistance must be reduce as low as possible. Otherwise, current may flow through to those who touch the damage electrical equipment instead of flowing through grounding system. In this project, a variety diameter of copper rod and galvanized iron rod were installed to build grounding system. The aim of this project is to find if there exists significance difference in the value of resistance when different diameter and different type of rod were used. Single rod testing and parallel rod testing were performed with fall of potential method to measure the value of earth resistance. Result shows that different types of rod with different diameter size produce different resistivity value which also depends on installation technique and soil condition.