Long time reader, first time poster: A question came up here at work regarding a small project where we want to provide 120 VAC on a machine fed with 380 VAC wye. One can purchase a multi-tap transformer with the options to use 2 legs of the 3 phase service, or one 220 VAC leg and neutral, on the high side and jumpering, and interconnecting as directed. My question is this: In this case, is one method inherently better than the other? I'm thinking from efficiency, heat generation, noise, or other power loss factors I don't know enough to consider. Both methods give you what you want in the end, which is single phase 120 VAC power with a Line and a Neutral, but there must be trade-offs in the design of such a transformer, no?