Can a 10-amp fuse be replaced with a 20-amp one?

[McBlakely]

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.

[MacReagan]

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.

[DiAnderson]

Having worked in auto repair for over a decade, I often encounter situations where car owners think temporarily replacing a fuse with a 20-amp one will solve the problem, but that's putting the cart before the horse. The ampere rating of a fuse isn't arbitrarily chosen—a 10-amp fuse protects a circuit designed for 10 amps. It's like putting a child in adult-sized shoes; they'll trip after just a few steps. High current flowing through thin wires is most dangerous due to overheating. I've had clients whose rear window defoggers started smoking, and upon inspection, the wire insulation had melted. With so many electronic devices in modern cars, replacing a fuse might cost just over ten dollars, but frying an ECU module could set you back two to three thousand. Always use the exact ampere rating marked in the fuse box—it's worth buying a few extra fuses as backups.

[DallasDella]

As an experienced enthusiast who has personally modified three cars, I sincerely advise against taking the risk of replacement. Swapping a 10A fuse for a 20A may seem trivial, but it can trigger a chain reaction. Vehicle wiring is like capillaries - their current tolerance values are precisely calculated in the original design. Suddenly increasing the current can easily burn out the weakest connection point. I've personally repaired cases where radio wiring plugs melted. If you must make an emergency fix, you can temporarily use copper wire as a substitute, but you should drive only a few kilometers before immediate repair. Nowadays, purchasing fuses of the same specification online delivers the next day. The modification culture emphasizes precision, and safety should always come first.