Can a 10-amp fuse be replaced with a 20-amp one?
2 Answers
No. The explanation is as follows: Brief: Generally, even if two fuses have the same nominal specifications, their actual resistances cannot be exactly the same when used in parallel. This leads to uneven current distribution. Even under normal circuit conditions, the fuse carrying a higher load current may burn out, causing both fuses to fail. Therefore, parallel use of fuses is not recommended, especially when mixing fuses of different capacities. Additional Note: A thermal fuse will indeed burn out due to overcurrent, but its primary function is to protect against excessive ambient temperature. When the environmental temperature exceeds the fuse's rated temperature, it will burn out and cut off the circuit, even if the operating current remains normal. This is different from standard current fuses.
I've seen many car owners directly replace a 10-amp fuse with a 20-amp one for convenience, thinking that a larger one won't cause any issues. In reality, this is extremely dangerous. The fuse in a car's electrical circuit serves as an overload protection device—it melts when the current exceeds the rated value to prevent the wires from overheating and catching fire. A 10-amp circuit can only handle 10 amps of current. If you suddenly replace it with a 20-amp fuse, even if the current reaches 15 amps, the fuse won't blow, causing the wires to continuously overheat. Last time, a car owner in our group did this and ended up melting the entire headlight wiring, costing over 800 yuan to repair. The correct approach is to check for any short circuits when a fuse blows, fix the issue, and then replace it with the original factory-specified fuse. Never gamble with safety.
