What is a defining feature of the wiring in single phase systems?

The defining feature of the wiring in single-phase systems is the use of a two-wire configuration, which is commonly referred to as a single-phase 2 wire system. This setup typically consists of one "hot" wire and one "neutral" wire, allowing for the delivery of electrical power to residential and light commercial applications.

In most single-phase wiring, the hot wire carries the current to the load, while the neutral wire provides a return path, effectively completing the circuit. This standard configuration is prevalent in homes, powering everyday appliances and lighting systems.

Other configurations, such as high voltage operation, do not necessarily define a standard single-phase system. A three-wire configuration is more characteristic of certain applications, such as where combined loads are used or for specific higher efficiency installations. The concept of variable phase supply is not applicable to single-phase systems, which are characterized by their consistent and fixed phase relationship in a circuit. Therefore, a single-phase 2 wire system is indeed the hallmark of single-phase wiring configurations.