Deep Dive: T0A05
The correct answer is C: Excessive current could cause a fire. A 5-ampere fuse should never be replaced with a 20-ampere fuse because excessive current could cause a fire. The 5-amp fuse was selected to protect wiring that can only safely handle 5 amps. A 20-amp fuse would allow 4 times more current, which could overheat the wiring and start a fire before the fuse blows. For amateur radio operators, this is a critical safety rule - always replace fuses with the same rating. Using a larger fuse defeats the protection.
Why Other Answers Are Wrong
Option A: Incorrect. A larger fuse wouldn't be more likely to blow - it would be less likely to blow, which is the problem. It allows dangerous currents that the smaller fuse would stop. Option B: Incorrect. Power supply ripple isn't affected by fuse size - ripple comes from the power supply design, not fuse rating. Option D: Incorrect. Since A and B are not correct, 'all of the above' cannot be correct. Only fire hazard is the real danger.
Exam Tip
Never replace 5A fuse with 20A = fire hazard. Think 'L'arger fuse = 'L'ess protection = 'L'ikely fire. Allows excessive current that can overheat wiring and cause fire. Always use the same rating.
Memory Aid
Never replace 5A fuse with 20A = fire hazard. Think 'L'arger fuse = 'L'ess protection. Allows excessive current that can overheat wiring and cause fire. Always replace with the same rating.
Real-World Example
Your equipment has a 5-amp fuse protecting wiring rated for 5 amps. You replace it with a 20-amp fuse because the 5-amp keeps blowing. Now, if a fault draws 15 amps, the 20-amp fuse doesn't blow, but the wiring can only handle 5 amps. The wiring overheats and could start a fire. The original 5-amp fuse was correctly sized to protect the wiring.
Source & Coverage
Question Pool: 2022-2026 Question Pool
Subelement: T0A
Reference: 2022-2026 Question Pool · T0 - Safety
Key Concepts
Verified Content
Question from the official FCC Technician Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the T0A topic.