> even in those cases, it's not 220v on one wire, it's just two wires of 110v. This is not really correct. Voltage is potential difference, so the voltage of a

> even in those cases, it's not 220v on one wire, it's just two wires of 110v. This is not really correct. Voltage is potential difference, so the voltage of a single conductor as measured from a single point is always zero, as there's no difference. Similar to how a boulder on top of a hill on Earth has potential energy from gravity, because there's a difference in height, and a force acting on that mass. That same boulder with no hill or gravity has no potential energy. In America, residential panels are generally wired with three current carrying conductors (hot, hot, neutral), and a ground. Each hot is one leg of a 240V transformer, and the neutral is a center tap, which has 120V of potential difference (voltage) between both hots. In 120V circuits, one hot is combined with the neutral for 120V of potential. Other circuits and outlets can combine two hots for 240V of potential, or two hots and a neutral for both 240V and 120V capability, such as might be used by your dryer, with large motors and heaters driven by the higher voltage, and control circuitry being powered by the lower voltage. > Are there any downsides for using 110v instead of 220v? Because the current required for the same amount of power at a lower voltage is higher (Ohm's law), thicker wire is required to carry that current, and more heat is generated. Source: DIYer who's wired my own garage, including a 100A subpanel and various circuits, which was all permitted and passed inspection.