What distinguishes a radial circuit from a radial-tie circuit?

A radial circuit is characterized by having a single source that supplies power and radiates outwards to various loads within a service area. This configuration allows for straightforward power distribution, where electrical devices are connected in a 'tree-like' manner, with each branch extending from the main supply. This setup is independent, meaning that if one branch fails, the remaining branches can still operate, as they are not reliant on other circuits for their function.

In contrast, a radial-tie circuit incorporates interconnections between multiple radial circuits. This design can enhance reliability because it allows for power to be rerouted if one circuit experiences an issue. However, the key distinguishing factor remains that a classic radial circuit's independence and its direct radiative connection to the service area set it apart from others.

The reasoning for the other options relates to their definitions and functionalities that do not accurately represent the fundamental characteristics of a traditional radial circuit. Radial circuits do not connect to multiple sources or depend on other circuits; they function primarily from a single source and maintain independence that contributes to reliable operation within their area.