1. Mechanical damage, for example, when lay the cable, construction is not standard, easily lead to mechanical damage.
2. Moistened insulation, usually occur in the cable joint of directly buried or in the exhaust pipe.
3. Chemical corrosion, cable lay in the acid solution function areas directly, easily lead to corrosion.
4. Enduring overload of running, especially in hot summer, the high temperature lead to aging of cable. So in the summer, cable failure is more.
5. The failure cable joint.
6. Outside environment and temperature.
7. The aging of the cable itself and natural disaster.