What main electrical safety feature protects against unintended voltage application?

Backfeed protection is primarily designed to prevent the unintended reverse flow of electrical current, which can occur during issues like power outages or faults in a system. This is particularly important in scenarios involving generators, where the generator could backfeed electricity into the utility lines, posing a severe risk to utility workers and others nearby. By preventing this backfeed, the protection mechanism ensures safety and maintains system integrity, effectively addressing the risk of unintended voltages being applied where they shouldn’t be.

While other options, such as ground-fault protection and surge protectors, also provide necessary safety measures, they target different issues. Ground-fault protection focuses on detecting imbalances in current flow to prevent shock hazards, while surge protectors are aimed at mitigating voltage spikes from external sources like lightning. Over voltage relays help in disconnecting power when voltage levels exceed specified limits. However, none of these options specifically address the scenarios of backfeed, making backfeed protection the most appropriate choice for preventing unintended voltage application.