To be precise, in a wye connected 3 phase system, if line to neutral is 240, the line to line would be 415 (240 x 1.732). I'm surprised there is 400 plus volts in a residential panel. I admit to having limited exposure outside the U.S. and no foreign residential expereince. The arc flash in a 240 volt panel is deadly enough. 400 volts is not something a typical homeowner has any business dealing with. My guess is with a moniker of "Pulpmillguy" there is an understanding of the dangers of higher voltages.