IEC TR 63040:2016(E) describes test results of research on dimensioning of clearances and creepage distances, for spacing equal to or less than 2 mm for printed wiring material and other equivalent arrangements of insulation, where the clearance and the creepage distance follows the same path along the surface of solid insulation. The information contained in this document is the result of research only and cannot be used for dimensioning the clearances and creepage distances for equipment within low-voltage systems, where IEC 60664-1 applies. However distances can be taken into account for functional reasons. This document provides results of research related to the following criteria: 1) clearances independent from the micro-environment; 2) creepage distances for pollution degree 1, 2 and 3 which extends the use of smaller distances to products having design features similar to printed circuit boards; 3) creepage distances to avoid flashover of the insulating surface; 4) information on minimum creepage distances to maintain minimum insulation resistance. A test method for the evaluation of the relevant water adsorption group for the surface of any insulating material which has not yet been classified is described.