Most people only have single phase power here in the US with +120 and -120 legs separated by 180 degrees angle. The power company steps the voltage down from a

Most people only have single phase power here in the US with +120 and -120 legs separated by 180 degrees angle. The power company steps the voltage down from a single phase on the distribution wires. Circuit breaker panels are set up with alternating legs so that the neutral current is approximately balanced whether you fill up the panel on one side first or from top down.