1. The problem statement, all variables and given/known data One of the reasons we use AC power instead of DC is that with AC, we can use a single wire with a maximum voltage of 220V to return 660V. This is done by combining 3 lines of 220V into a single one. How can this be done without exceeding the wire's max voltage of 220V? My teacher also added this to clarify, "Ha, I realized that I was thinking in European terms, where they use 220V. Anyway, suppose I have an appliance (like an AC) that needs 660V to run. I can run this by connecting 3 220V wires to it, just like you'd use 3 4V batteries to run something that needs 12V. Suppose each wire can hold a maximum of 10A, and that's what's going through the 3 incoming wires. Now, there is a trick I can use to only need a single return wire (as opposed to the 3 incoming wires), even though it seems it would have to carry 30A (which is more than it can hold). What is the trick?" 2. Relevant equations My only thought was that one could use a transformer to take (incoming) 660V in 3 wires into 1 wire of 220V. But then would I have 3 turns on one end and one on the other? [tex]\Delta[/tex]V2 = N2/N1 * [tex]\Delta[/tex]V1 3. The attempt at a solution 220V = x/3 * 660V But then x=1 turn, and what current or voltage would it carry?