Most dangerous consequences of using electricity are electric shock and electric fire. They are usually caused by damaged insulation, overheating of cables or damp conditions.
- Rubber is used as insulation for the current-carrying conductors of most electrical appliances.
- Rubber insulation is prone to damage due to regular bending and twisting. (Common appliances that bend/twist during usage: Hair dryer and Iron) The rubber insulation might break apart and expose the wire.
- This damaged insulation would result in
- Electric shock $\rightarrow$ resulting in serious injury or even death to users.
- Short circuit in the current path by connecting exposed current-carrying conductors together $\rightarrow$ resulting in the wires heating up $\rightarrow$ fire hazard.
Overheating of cables
- Especially thin wire conductors, when very large currents are made to flow through these conductors, these wire conductors will heat up and produce very high temperatures. Short-circuit or overloading of cables are conditions that lead to such large currents.
- This overheating of cables would result in melting of the insulation and catching fire.
- Effective body resistance drop drastically from 100 kΩ to 100 Ω under damp condition (wet environment condition). Activities like sweating, bathing and etc lower the effective resistance of our body.
- This damp condition, coupled with unsafe usage of electrical appliances, would result in large currents flowing through our body causing electrical shock and leading to serious injury or even death.