I realize that 277V is derived from a 3-phase Y transformers' line-line voltage (480V/1.732). So, my way of thinking is that if you draw a 3-phase Y transformer, you would connect your load (in this case lighting) say from a-phase to b-phase. But that is not the case, there are not 2 phases there, there is instead a hot and a neutral. Where did the neutral come from? How is 277V lighting wired? And why is it dangerous to work on energized 277V lighting circuits?