Speculatively, in NYC there are probably some old basement motor-generator sets that are owned and maintained by Con Ed for changing the utility’s local AC to DC, presumably upstream of a DC watthour meter. There might also be some “modern” transformer-silicon rectifier-reactor-capacitor converters. Voltage likely would be around 110/220V DC, consistent with the history of ‘Edison 3-wire’ service. Long Shot Guess is that there may some ancient elevator or ventilation motors, and maybe a trace of incandescent lighting in common areas.
