Increase in Dimensions Due to the Covering
|Larger dimension of conductor||Minimum increase in dimensional over actual conductor dimensions||Maximum increase in dimensions over maximum permissible conductor dimensions|
|Over||Up to and including||Grade 1||Grade 2||Grade 3||Grade 1||Grade 2||Grade 3|
NOTE: The maximum increase in dimensions may be amended when IEC Recommendation is published
1. Adhesion and Flexibility
1.1 As received. Samples of the glass-covered conductor shall be bent through 180° round a mandrel having a diameter 10 times the bare width of the conductor when it is bent on edge, or 10 times the bare thickness when it is on the flat. Separate samples shall be bent, one on edge and one on flat and when so tested the covering shall not open sufficiently to expose the bare conductor to view, when examined under diffused light by normal eyesight. There shall be no appreciable loosening of the insulation.
1.2 After heating. Samples which have been heated for 16 h in an oven at a temperature of 150°C to 155°C and then allowed to cool to room temperature, shall pass the test for flexibility and adherence specified in 1.1.
2. Breakdown voltage. The wire shall meet the requirement of 2.1 and 2.2. when tested at room temperature and at elevated temperature respectively.
2.1. Tests at room temperature. Samples shall be subjected to a breakdown voltage test by the method described in Appendix E. At least four of the five places tested shall not break down at a voltage less than the appropriate value in Table 4, and the fifth at a voltage not less than 50% of the required value.
2.2. Test at elevated temperature. When tested by the method described in Appendix E, at the rated temperature, at least four of the five samples tested shall not break down at a voltage less than the appropriate value in Table 4, and the fifth at a voltage not less than 50% of the required value.