The ASTM standard for testing the dielectric strength of transformer oil is ASTM D1816. This standard outlines the procedures for measuring the dielectric breakdown voltage of insulating oils, which is crucial for assessing their performance and reliability in electrical applications. Ensuring proper transformer oil dielectric strength is essential for preventing electrical failures and maintaining the longevity of equipment. Using a Globecore dielectric strength tester can provide accurate and reliable results in accordance with ASTM D1816 standards.