kct creepage with --standard iec60664 keys the clearance lookup on steady-state peak working voltage instead of the rated impulse withstand voltage, so mains clearance comes out 0.2 mm instead of 1.5 mm: about 7x under-specified and non-conservative. The lookup table also carries 3200 V and 6300 V rows that are not on the IEC preferred impulse series. The curator reproduced every reported number against origin/main.