Hi

I dont know enough about the operations and standing loads of VDF to make any useful comments rc, i just added the bits about the wiring to it as i have made majic smoke with electronics a few times before... and have noticed after strip down from large pops, degradation of insulating wires around the dump or earth load, there is one that springs to mind with HID lighting, it seemed fine unter test, but kept blowing ballasts, after stripdown of the wires, the wires had dried and slightly swelled. Under low load test, things seemed fine, but would blow windings under load, especialy once it had dried out the cable enough..... there was no sign on the outside of the cable of the swelling/drying

Its sounds more likeley that its a dodgy component and you have just been very unlucky,