Exam Question

### (a) Possible Causes of Electrical Fires
#### (i) Switchboards (3 Causes)
1. **Loose or Corroded Connections:** This is a primary cause. A loose connection at a busbar joint, circuit breaker, or cable termination point creates a high-resistance path. According to Joule's Law of heating ($$ P = I^2 \times R $$), even with normal current (I), the high resistance (R) at this single point generates intense, localized heat. This can lead to the melting of conductors, breakdown and ignition of insulation, and arcing between phases or to earth, initiating a fire.
2. **Overloading of Circuits:** When a circuit is forced to carry a current exceeding the design capacity of its components (busbars, fuses, circuit breakers), generalized overheating occurs. While protective devices are designed to prevent this, their failure, incorrect rating (e.g., oversized fuse), or repeated tripping without investigation can lead to the thermal breakdown of insulation material, which then combusts.