Covers minimum requirements for ventilated and electrically heated single-chamber ovens, with or without forced air circulation and operating over the temperature range from 20°C above ambient to 500°C used for thermal endurance evaluation of electrical insulation. Gives acceptance tests and in-service monitoring tests for ageing ovens. IEC 60216-4-1 (1990) supersedes the second edition of IEC 60216-4 (1980).