Question 256Electricity & Electronics - 1st Asst/Chief

The correct answer is C) 4.3 megohms. The insulation resistance to hull ground for a 3.3 kV motor should be a minimum of 4.3 megohms, as per the requirements of the U.S. Coast Guard for electrical systems on vessels. This value is based on the formula of 1000 ohms per volt, which is the industry standard for minimum insulation resistance. For a 3.3 kV motor, the minimum insulation resistance would be 4.3 megohms (3300 V x 1000 ohms/V = 4,300,000 ohms or 4.3 megohms). The other options are incorrect because 2.3 megohms (A) and 3.3 megohms (B) are below the required minimum, while 6.6 megohms (D) is higher than the minimum standard.