Insulation resistance

A value indicating the insulation performance of electrical and electronic equipment. To prevent failures or electric shock caused by current leakage, the insulation resistance must be at or above the specified value. It is determined by using an insulation resistance tester to measure the minute current that flows when a DC voltage of 500V or 1000V is applied either between a designated measurement point inside the equipment and the ground, or between two designated points inside the equipment. According to the technical standards for electrical installations, the value must be 0.1MΩ or higher for voltages of 300V or less (150V or less to ground). This value decreases in conditions of high humidity, such as during rainy weather. When this value becomes smaller, current leakage is more likely to occur.