My understanding is commercial/industrial service is normally 3-phase but residential service is typically only single-phase. Wikipedia says that gets supplied as two 120V AC lines that are 180° out of phase with each other along with a shared neutral.
My understanding is commercial/industrial service is normally 3-phase but residential service is typically only single-phase. Wikipedia says that gets supplied as two 120V AC lines that are 180° out of phase with each other along with a shared neutral.