Electrical Inspection, Testing and Certification Practice Exam

To determine the insulation resistance at the board with the recorded values, it's essential to understand how to combine insulation resistance measurements. Insulation resistance is typically evaluated in parallel when multiple measurements are taken from different parts of the system.

The resistance values given—10 Mohm, 5 Mohm, 4 Mohm, and 6 Mohm—can be combined using the formula for resistances in parallel, which states that the equivalent resistance (R_total) can be calculated as:

1/R_total = 1/R1 + 1/R2 + 1/R3 + 1/R4

In this case, the calculation would be:

1/R_total = 1/10 + 1/5 + 1/4 + 1/6

Calculating each term, we find:

- 1/10 = 0.1

- 1/5 = 0.2

- 1/4 = 0.25

- 1/6 ≈ 0.1667

Now, adding these values together gives:

1/R_total ≈ 0.1 + 0.2 + 0.25 + 0.1667 ≈ 0.7167

To find