ConEd standard* service in NYC provides 120/208 three or four wire service from a wye connected transformer bank. With the density of the city it's easier to ju

ConEd standard* service in NYC provides 120/208 three or four wire service from a wye connected transformer bank. With the density of the city it's easier to just run three phase all over and let homes pull alternatingly off the hots. So homes connect A-B, B-C, A-C and so on. Three wire service means you get two hots and a neutral and is considered a single phase "open wye" service. BUT you can reconstruct the third phase from the two half vectors in each phase using transformers. Four wire gives you full three phase service so you can run big motors, machinery, lots of lighting and such. *Though plenty of neighborhoods are fed 120/240 or mixed. I'm on 120/240 yet the next block is 120/208. Sucks because I want my three phase.