Which standards govern insulator testing in many countries?

• A. IEC standards and national standards (e.g., IS, ANSI/IEEE) depending on the country
• B. Only national standards are used
• C. Only IEC standards are used
• D. International standards (ISO) exclusively

Answer: (A)

The key idea is that insulator testing follows a mix of standards: international guidelines from the IEC plus national standards that each country may adopt or adapt. The IEC sets widely used test methods and performance criteria for insulating materials and equipment, giving a common foundation that manufacturers and testers can reference globally. But many countries also have their own national standards or regulatory requirements (for example IS in India, ANSI/IEEE in the United States, or other national documents) that may modify, supplement, or mandate specific details such as test voltages, sample sizes, safety factors, or certification processes. ISO, while important for general quality and management systems, is not the primary source for the technical test procedures used for insulators.

So the best answer reflects both international IEC standards and the national standards that apply in a given country.