"A mistaken belief is that AC is more efficient than DC. What AC is is more easy to transform from one voltage to another (until somewhat recently). That makes

"A mistaken belief is that AC is more efficient than DC. What AC is is more easy to transform from one voltage to another (until somewhat recently). That makes it easier to run AC at 1 MV and then step it down to 240V for residential applications." DC is also used because a conductor can carry more current per kg than AC due to not having any skin loss. You can use smaller wires, less metal, less dollars.