A fuse is a thermal circuit protection device which protects distribution system cables and components against excessive electrical currect when failures occur. Fuses are rated to a specific maximum current specified in amperes and will rupture (meaning that the fusible will melt and open the circuit) at a slightly higher value to accomodate surge as a load is switched on and is in series with the load it protects.

If you replace a fuse with a higher amp one it will work but create an unsafe circuit. It could cause a failure of the device burn it up, start a fire. The fuse is designed as a safety device. It should not only be the correct amperage but also the correct voltage and fast or slow blow. In other words, if an over-current is allowed - by fitting an incorrect fuse rating, for example - there is a severe risk of an electrical fire.

However, it is important to note that, in a healthy circuit, nothing will happen as long as the circuit does not encounter an overload condition. If the circuit does encounter an overload condition then that part of the circuit that the fuse protects may become a fire hazard.

Note: Some students have confirmed that the option "Overcurrent might go undetected and cause a fire." was correct in their exams and confirmed that the option "In a healthy system nothing problematic will happen." was not within the available answers. However, we have also received a couple of feedback confirming the correct option to be "In a healthy system nothing problematic will happen." which makes us believe that there are at least two similar question.