Why is 120/208 volt 3 phase used mostly in commercial buildings, and not 120/240v like residential single phase homes? (My question is not about the single or 3 phase, but about 208 vs 240v). What is the 3 phase 208v wild leg usually used for in commercial panels?
Also since romex (NM) is not allowed in commercial buildings, has anyone ever seen an application where 277/480v was used, using NM? NM insulation is good for 600v.

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