Section 6.2.2 of ANSI/NEMA HP-3 specifies the high-frequency or impulse spark test for insulated high-temperature hook-up wire. The test is conducted per NEMA WC 52 or WC 56.
The spark test detects faults and thin spots in the insulation that could lead to dielectric failure in service. It is a critical production quality test for high-temperature wire used in appliance and industrial applications.