Charging circuit indicator lamps are installed so that they will not light when?

Charging circuit indicator lamps are designed to illuminate under specific conditions to indicate a fault or a status within the charging circuit. When the voltage on both sides of the lamp is equal, it means there is no potential difference to drive current through the lamp. For the lamp to light up, there must be a difference in voltage between the two terminals of the lamp. If the voltage on both sides is equal, there is no current flow, and thus, the lamp remains unlit.

In contrast, if the lamp is burnt out, the circuit becomes open, and the lamp wouldn't light due to lack of continuity. A blown fuse would also break the circuit, preventing the lamp from receiving power to light up. And if the current is too high, it could potentially damage the lamp or other components but wouldn't necessarily prevent it from lighting up; instead, a high current might overwhelm the components, leading to failure. Hence, the condition of equal voltage on both sides is the definitive way to ensure that the lamp does not light.