*Question T0A05:
Why should a 5-ampere fuse never be replaced with a 20-ampere fuse?*  

*Correct Answer is  C: Excessive current could cause a fire*  

### AI Response: (may contain errors)  

To understand why a 5-ampere fuse should never be replaced with a 20-ampere fuse, let's analyze the implications of using a fuse with a higher rating.

### Correct Answer: C - Excessive current could cause a fire

- **Explanation**: A fuse is designed to protect electrical circuits by breaking the circuit when the current exceeds a certain level. If you replace a 5-ampere fuse with a 20-ampere fuse, the circuit can draw up to 20 amperes before the fuse blows. This can lead to excessive current flowing through the wiring and components, which may not be rated for such high currents. This excessive current can generate heat, potentially leading to insulation failure, short circuits, and even fires.

### Why the Other Choices are Incorrect:

- **A: The larger fuse would be likely to blow because it is rated for higher current**  
  - **Explanation**: This statement is incorrect because a 20-ampere fuse is less likely to blow under normal operating conditions compared to a 5-ampere fuse. The larger fuse is designed to allow higher currents to pass without interruption, which is the opposite of what this choice suggests.

- **B: The power supply ripple would greatly increase**  
  - **Explanation**: While using a larger fuse may affect the overall performance of the power supply, it does not directly cause an increase in power supply ripple. Ripple is more related to the filtering and regulation of the power supply rather than the fuse rating. Therefore, this choice does not accurately address the primary concern of safety.

- **D: All these choices are correct**  
  - **Explanation**: Since choices A and B are incorrect, this choice cannot be correct. The only valid concern is the risk of excessive current leading to potential fire hazards.

### Summary

- **Key Takeaway**: Always use a fuse that matches the current rating required for your circuit. A fuse is a safety device, and using one with a higher rating than necessary can compromise safety and lead to dangerous situations.

### Rule of Thumb

- **Fuse Rating**: Always select a fuse that matches the maximum current rating of the circuit or device it protects. This ensures that the fuse will blow before the current exceeds safe levels, preventing damage and hazards.