Distinguish insulation resistance testing from continuity testing.

• A. Insulation resistance checks leakage between conductors/ground; continuity checks if a circuit path is complete.
• B. Insulation and continuity are the same test.
• C. Insulation resistance checks voltage drop along a wire; continuity checks resistance.
• D. Insulation resistance checks current; continuity checks insulation.

Answer: (A)

Insulation resistance testing assesses how well the insulation between conductors (and between conductors and ground) resists leakage current. By applying a high DC voltage with a megohmmeter, you measure leakage as a resistance value in megohms. A high resistance means the insulation is good and leaking only minimally; a low resistance indicates insulation problems, moisture, or contamination.

Continuity testing, in contrast, checks whether a conductive path between two points actually exists. It uses a low-voltage, low-current test to determine if there is a complete circuit, often yielding a near-zero ohm reading or a beep if continuity is present. It does not evaluate insulation quality or leakage.

So the best distinction is that insulation resistance testing looks for leakage between conductors or to ground, reflecting insulation integrity, while continuity testing confirms whether a circuit path is physically complete.