IEC 60587:2007 describes two test methods for the evaluation of electrical insulating materials for use under severe ambient conditions at power frequencies (45 Hz to 65 Hz) by measurement of the resistance to tracking and erosion, using a liquid contaminant and inclined plane specimens. The two methods are as follows: - Method 1: constant tracking voltage; - Method 2: stepwise tracking voltage. The main changes from the previous edition are as follows: experience has indicated the need for improved description of the experimental method. For the preparation of the test specimens abrasion is recommended only if necessary. The ventilation of the test chamber is described in detail. For specimens of soft elastomeric materials a mounting support is described. The maximum depth of erosion has to be reported in the classification.