I've built another high current high voltage power supply with no other purpose than drawing giant arcs. This time up to 2m long. This high voltage power supply contains 8 MOTs (transformers from microwave ovens) connected to two groups of four. In each group, the MOTs are connected both primaries and secondaries in parallel. These two groups are then connected in series (both primary and secondary) and powered from 400V~ phase to phase mains voltage. When connecting the power supply to the mains, the inrush current has to be limited. For this I use a modified ballast for a 150W high pressure sodium discharge lamp (made by TESLA). I've removed the "U" part of the iron core, leaving only the "T" part. After the modification, its inductance is about 35 mH. This inrush inductor could be replaced by a heater element, probably rated 230V and at least 2kW. After connecting the power supply to the mains, the inrush inductor is bypassed using a switch. On the secondary side there are resonant capacitors taken from microwave ovens. Each capacitor is approximately 1uF 2100V~. I got the best results with 12 to 16 microwave oven capacitors (6 to 8 on each side). If I used even more capacitors, the circuit breaker would trip too early. The reason to use secondary resonant capacitors is simple: With them, you can get longer high voltage arcs :). Thanks to the resonance, you can reach a high secondary current while the primary current isn't too high for the circuit breaker. This power supply is not designed for continuous operation. Output voltage is about 4000V~. With 14 capacitors (7+7) and 400Vac input, this high voltage power supply draws about 4.3A idle current, about 23A with the output shorted out and up to 41A when drawing the longest arc. My 25A class B circuit breaker does not trip sooner than after tens of seconds of operation. The secondary arc current is about 7A. As one of the electrodes I used an upside down metal can with salt on top. The salt colors the arcs to brighter orange and probably makes them a bit longer.