What is the minimum time required to test a cable?

What is the minimum time required to test a cable?

• A. 1 minute
• B. 2 minutes
• C. 3 minutes
• D. 4 minutes

Answer: (C)

When testing a cable with an insulation-resistance meter, you need enough time for the insulation to settle and for leakage currents to stabilize. Right after you apply the test voltage, the insulation acts a bit like a capacitor and leakage paths can cause a transient current. If you read too soon, the measurement can be misleading. Three minutes is the minimum dwell time used here to allow the current to decay to a stable, representative value, so the resistance you record reflects the actual insulation resistance rather than transient effects. If the reading isn’t within spec after this period, you’d review the cable and test setup or extend testing per procedures. Temperature and cable length can influence the reading, so tests are done under prescribed conditions and values.

When testing a cable with an insulation-resistance meter, you need enough time for the insulation to settle and for leakage currents to stabilize. Right after you apply the test voltage, the insulation acts a bit like a capacitor and leakage paths can cause a transient current. If you read too soon, the measurement can be misleading.

Three minutes is the minimum dwell time used here to allow the current to decay to a stable, representative value, so the resistance you record reflects the actual insulation resistance rather than transient effects. If the reading isn’t within spec after this period, you’d review the cable and test setup or extend testing per procedures. Temperature and cable length can influence the reading, so tests are done under prescribed conditions and values.