Clamp type earth resistance tester is a major technologicalClamp type earth resistance tester breakthrough in traditional grounding resistance measurement. It is widely used in the grounding resistance measurement of electric power telecommunications meteorology oilfield construction and industrial and electrical equipment. When measuring circuit grounding system it is not necessary to disconnect the each connection wire and use auxiliary electrode it is safe and quick easy to use. Can measure the grounding fault which can not be measured by the traditional method because this instrument measure the integrated value of grounding resistance and ground lead resistance apply to the occasion that can not use the traditional method.