The main reason why wires burn and melt is: circuit overload or short circuit.
Wires have a certain resistance, and the resistance of the wires will generate heat when current passes through them. Due to the small cross section and high resistance of the wires, the total current of electrical appliances exceeds the carrying capacity of the wires. If the heat is too high, the wires will become hot and melt. If there is a short circuit and a huge current is generated, the wire will melt instantly.
In fact, this sound is caused by the ionization of air near power lines, forming a corona discharge. Since the air is humid on rainy days and has lower resistance than on dry days, the high voltage lines will discharge into the surrounding air and emit a humming sound, but no arcing or sparking will be generated. So when you hear a buzzing next to a lihigh voltage gene, don't doubt it, it's a discharge. However, this only happens when some wires have burrs or are connected to posts. It does not enter the air and has no impact on people or objects.