How long should the residual voltage of a capacitor rated not over 1,000V be reduced after it is disconnected from the power source?

The correct answer is based on standard safety procedures related to capacitors and their disconnection from power sources. For capacitors rated at not over 1,000V, it is recommended to allow a time period of 1 minute for the residual voltage to dissipate after disconnection. This timeframe is considered sufficient for the capacitor to discharge naturally, thus avoiding potential electrical hazards when working with these components.

Capacitors can retain substantial charge even after being disconnected, making it important to allow adequate time for their voltages to drop to safe levels. A one-minute wait ensures that the voltage reduction is likely to occur effectively, minimizing the risk of electric shock to individuals handling or servicing related systems.

The other options suggest either shorter or longer waiting periods that are not aligned with commonly accepted safety practices. A shorter duration may not allow sufficient discharge time, while a longer duration could be unnecessarily cautious, potentially leading to inefficiencies in maintenance and service routines involving the equipment.