The cause why electrical appliances on board can get fire or explode is complicated and special. If electrical appliances does work properly or are not applied or managed in a right way, there will be hidden danger which can be heating or fire source of fire.
There are normal and abnormal heating source of electrical appliance, spark from on and off joint, short circuit point of insulation, and broken point of cable, for example. There are normal high temperature components such as light; there are also abnormal high temperature. Electrical appliances especially for socket can get short circuit or grounding due to water inside. The point of short circuit or grounding will be very hot. Long time over working of electrical appliances or cable or short circuit can also cause high temperature. There are also excessive current and high temperature caused by abnormal electrical pressure. Wrong management and connection of electrical cables or application of heater or other electrical appliances which surpasses the allowed current carrying capacity for cables will also cause high temperature.
Normal and abnormal spark and high temperature all may cause fire or explosion. That normal fire or heating source meet combustible material is also likely to cause fire.
Special part of ship is easy to get fire or explosion, such as rechargeable batteries for emergency power supply of ship and battery room. During charging, battery can generate hydrogen,which is lighter than air. If battery room is not equipment with ventilating devices, or ventilating devices do not work normally, hydrogen will be accumulated on top of the room. Once there is fire source or spark, it will explode.