Creepage distances of basic insulation shall not be less than those specified in Table 17. However, if the working voltage is periodic and has a frequency that exceeds 30 kHz, the creepage distances shall also be determined from Table 2 of IEC 60664-4. These values shall be used instead if they exceed the values in Table 17.Except for pollution degree 1, if the test of Clause 14 has been used to check a particular clearance, the corresponding creepage distance shall not be less than the minimum dimension specified for the clearance of Table 16.Table 17 – Minimum creepage distances for basic insulationCompliance is checked by measurement.