The major reasons for electrical short circuits include the following: 1. Wires being chewed through by pests or vermin 2. If an electrical wire comes in contact with water or other fluids 3. Faulty connection in the electrical wiring of appliances 4. Old or damaged outlets, switches, lights, appliances, or other electrical devices 5. Abnormal build-up of electrical currents 6. Walls pierced by nails or screws come into contact with live electrical lines.