The Russians seem to favour welding for splicing household-sized conductors in junction boxes. I've seen several Youtube videos on that topic. Here's one of them: https://www.youtube.com/watch?v=KgOKhfVON4Y (not that I'd recommend his twisting technique, feels much too likely to put too much stress on some conductors, eventually breaking them)
His equipment looks very much like a graphite block wired to a plain welding inverter/transformer.
