Thanks, but I understand about single- or split-phase wiring. The question is about how to wire this water heater that has only one spot for landing a hot wire, not two like a standard U.S. appliance. The specs are for 220V and 50 or 60 hz so it will operate in a variety of countries. The Philippines, where I bought the water heater, is 220V@60hz, the U.K. is 230V@50hz; both supply the voltage with one hot wire -- true one-wire single-phase, not the U.S. version of two-wire split-phase. The heater is set up to be hard-wired, not cord & plug. It also has a 4-position power switch (off and three heat levels), with two power lines to the element and I guess neutral/negative wires to anodes or cathodes all into the top of the tank. Is it as simple as landing L1 on the terminal's L screw and L2 on the N terminal? Or would answering that require a diagram of the heater's inner wiring? It's an undersink model, so all that wiring is exposed.