1. Overload: If the circuit that the fuse is protecting is drawing more than 30 amps, the fuse will heat up and eventually blow. This can be caused by a short circuit, a faulty appliance, or simply too many devices plugged into the circuit.
2. Loose connection: If the fuse is not properly seated in its holder or if there is a loose connection in the circuit, the fuse will heat up due to the increased resistance.
3. Defective fuse: In rare cases, a fuse can be defective and will heat up even if the circuit is not overloaded or there is no loose connection.
If a 30 amp mini fuse is getting hot, it is important to investigate the cause and correct the problem as soon as possible to prevent damage to the circuit and/or the fuse.
