Input please on 25 cycles radios 1930ish

[Conchord]

Originally Posted by gadget73

277v comes from running one leg of a 460v 3 phase supply to ground. Nothing special about it. Lighting in industrial complexes is commonly 277v single phase, since its really simple to make that from the 460v 3ph mains. Where I work, we have 460v 3ph supplies, 277v lights in the warehouse, and a few 240 and 120v systems as well. We get our 240 and 120 from a couple of big step-down transformers installed throughout the building.

Its 480v, not 460v. There is certainly nothing special about it. 277V single phase is not a commonly used term, 480 single phase is however. While it may be a misnomer, this is what they're called: 277 or 480 single phase for a hot/neutral or two hots respectively.