A method for coating a surface of an electrically non-conductive substrate with powder coatings, the method comprising the following steps: providing a substrate to be coated, pre-heating the substrate to be coated to a temperature of 40 to 140° C. in order to decrease the surface resistance of the substrate to less than 1012 ohms, preferably to within the range of 1010 to less than 1012 ohms, electrostatically coating the surface with powder coating in a single layer, which powder coating comprises a reactive system which, in particular, cures into a thermoset, curing the powder coating layer at a temperature of 170° C. or less.