New York city residential premises have two phases coming in whereas commercial/industrial would have a three phase feed both 120v and 277v, but in reality the voltage varies depending where you are. Example say in a residential location black and red each carry about 116/115v, each phase is 120 degrees out with each other. With appliances like cookers and AC’s both legs are wired in a delta configuration that amounts to about 200V. Take a reading of one of the phases and multiply it by SQ root of 3 or put your meter across any two phases for an accurate measurement. I don't know if you have a 220v single phase feed in your location as the system changes from county to county or state to state but thats how its done if you require more I squared R and you have access to two or three phases. In the UK/Ireland only one phase fed to residential premises and that’s supposed to be on average 230v. I have measured it as low as 214v and as high as 248v in the space of a day at my last address. No point biasing my amp at that place eh. I called the electricity supplier and they sent a guy out to check the mains but he hadn’t a clue what he was doing, I don't even know if he was even an electrician as he looked too scruffy. I don't recommend pulling the plug out from the wall either to switch anything off as there is usually an arch flash but I've done it loads of times in a hurry. BTW I once had my old electric meter rigged with an inductor to turn the wheel backwards whenever I wanted. One time I wound it back so far I must have been in about 1000 bucks worth of credit. Knowing that the meter reading man was coming at the end of the month I had every applience in the house running flat out to get back into the red. In the coming winter I intend to jumper wire the meter completely with a piece of #4 wire as my house is all electric heated.