What network is the least reliable if a fault occurs?

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Reliability of a distribution network hinges on having alternative pathways for current when a fault occurs. A radial distribution line carries power from a single source to loads along one path with no alternate route. If a fault happens, there is no second path around it, so all customers downstream from the fault lose supply until the fault is cleared and that section is energised again. Protective devices can isolate the fault, but outages will extend to the portion fed from that line. In contrast, a ring distribution line forms a closed loop, offering an alternate route around a fault so power can often continue to be supplied from another direction. Mesh networks have multiple interconnections, giving several possible paths and higher resilience during faults. Network designs usually emphasize redundancy and interconnected feeders, further boosting reliability. So, the radial distribution line is the least reliable when faults occur.