Three factors determine the resistance of a substance to the flow of electricity. What it is made of. Substances with very little resistance to the flow of electrical current are called conductors . Examples are metals. Substances with such a high resistance that they can be used to prevent the flow of electrical current are called insulators .
Examples are glass, porcelain, plastic, and dry wood.
Therefore, although dry wood is a poor conductor, when saturated with water it becomes a ready conductor. The same is true of human skin. When skin is dry, it is a poor conductor of electrical current. When it is moist, it readily conducts electricity. Use extreme caution when working with electricity where there is water in the environment or on the skin.