The purpose of this article is to propose a method for investigating the influence of the impulse voltage waveform generated by inverters based on wide bandgap semiconductors on the insulation endurance of magnet wires. In this regard, endurance tests of enamel insulation are performed on a designed test bench, which generates repetitive voltage pulses with ns-level rising and falling times corresponding to modern silicon carbide-based inverters. Furthermore, we suggest a novel specimen's shape for testing enameled rectangular section magnet wires which find their application in electric traction motors. Considerations related to the deterioration of dielectrics subjected to impulse voltage with high slew rates and high switching frequency are given.