In what scenario is a transfer switch used?

A transfer switch is used to switch between different power sources, which is essential for maintaining electrical supply during power outages or when performing maintenance on the primary power source. Its primary function is to ensure that power can be safely directed from an auxiliary source, such as a generator, to the electrical system without the risk of backfeeding into the grid or causing damage to equipment. This is particularly critical in applications where continuous power is necessary, such as hospitals, data centers, and critical infrastructure.

In contrast, the other scenarios listed do not align with the primary purpose of a transfer switch. Circuit overloads are addressed through circuit breakers, which are designed to interrupt the circuit to prevent overheating. Lighting control falls under switches, dimmers, or smart home systems that manage illumination levels rather than switching power sources. Changing breaker types involves modifications or upgrades to the circuit breaker itself and does not require a transfer switch, as this process deals with internal circuit protection rather than external power supply management.