Single-phase distribution lines

Distribution lines can be configured in different ways depending on how the lines are wired into the transformer at the substation. Lines may be single-phase or three-phase.

A single-phase line

In a single-phase configuration there are two wires: a single “hot” phase line and a neutral wire. They are commonly tapped off a three-phase feeder by connecting the single-phase line to one phase line of the three-phase circuit using a line fuse or a fused cutout. The second neutral wire is tapped to the neutral wire in the three-phase circuit. Because single-phase lines only require two wires, they are cheaper than three-phase lines.

A series of single-phase lines tapped off a three-phase feeder

Single-phase lines are used in areas with primarily residential and small commercial customers since larger customers often require three-phase service.