What type of underground electric system has secondary mains supplied by multiple primary feeders?

The type of underground electric system that has secondary mains supplied by multiple primary feeders is the secondary network system. This configuration is specifically designed to enhance reliability and capacity. In a secondary network, several primary feeders distribute electricity to multiple secondary mains, allowing the system to balance loads and provide power from different sources.

This design offers advantages such as reduced outages and improved service continuity, as power can be rerouted in case of maintenance or failure in one of the feeders. Furthermore, the interconnected nature of the system helps in managing peak loads more effectively, as it can share demand across multiple supply points.

The other types of systems, such as radial or looped configurations, do not typically combine multiple primary feeders serving the secondary network in the same way. Radial systems typically have a single source feeding several consumers, while looped systems involve redundancy but do not connect multiple primary feeders in the manner described. Horizontal systems generally refer to a different structural setup not directly related to the question about secondary mains.