Mike Dolt Enterprises
Mike Dolt Enterprises
User: erickench, Location: Brooklyn, NY
Asked on: Friday, April 1, 2011 at 6:35 pm EDT
Answered on: Tuesday, May 14, 2024 at 3:38 am EDT
Question: Hi Guys, I'm getting ready to take a state civil service test and I'm using a Passbook to prepare for the test. I came across an interesting question which I can't say that I agree with the answer as given in the answer key. Here goes:The best way to determine the insulation resistance of a new wiring system installed in conduit would be to measureA. between individual wires onlyB. from each wire to conduit onlyC. between individual wires from each wire to conduitD. from the hot legs to the neutralMy choice was 'C' because you are looking for leakage between a wire and ground in this case being the conduit. But I could be wrong. The answer key gave 'D' as the answer which doesn't make any sense to me. What do you think?
The correct answer is C. between individual wires from each wire to conduitExplanation:
Insulation resistance measures the resistance between conductors and ground. In a wiring system installed in conduit, the conduit serves as the ground reference. To determine the insulation resistance, you need to measure: Between individual wires: to check for insulation breakdown between the wires. From each wire to conduit: to check for insulation breakdown between the wires and the conduit (ground).Measuring from the hot legs to the neutral (option D) does not provide any information about insulation resistance to ground.Therefore, the best way to determine the insulation resistance of a new wiring system installed in conduit is to measure between individual wires and from each wire to conduit. Flag for review