Electrical Inspection, Testing and Certification Practice Exam

When testing insulation resistance, which items should be disconnected?

1. All current-using equipment, neons, and voltage-sensitive electronic equipment

2. All lighting fixtures and outlets

3. Only high-voltage equipment

4. Only grounding connections

The correct answer is: All current-using equipment, neons, and voltage-sensitive electronic equipment

When testing insulation resistance, it is crucial to disconnect all current-using equipment, neons, and voltage-sensitive electronic equipment to ensure accurate readings and prevent damage. These devices could create a path for current to flow, thus affecting the insulation resistance test results. If any of these items remain connected during the test, it can provide misleading values, indicating that the insulation is in a better condition than it actually is due to the current bypassing through these devices. Disconnecting all current-using equipment eliminates interference and allows for a true assessment of the insulation integrity of the wiring system. Neons and other sensitive devices could also fail if exposed to the test voltage typically applied during insulation resistance testing. Therefore, ensuring they are disconnected is essential to perform a safe and accurate insulation resistance measurement.