Hazards
Damaged Insulation
- Rubber is used as insulation for the current carrying conducts of most electrical appliances.
- Rubber insulation is prone to damage due to regular bending and twisting. The rubber insulation might break apart and expose the wire.
- This damaged insulation would result in.
- Electric shock: result in serious injury or even death to users.
- Short circuit in the current path by connecting exposed current carrying conductors together which results in wires heating up that is a fire hazard.
Overheating of Cables
- Especially thin wire conductors, when large currents are made to flow through these conductors these wire conductors will heat up and produce extremely high temperatures.
- Short circuit or overloading of cable are conditions that can lead to such large currents.
- This overheating of cables would result in melting of the insulation catching fire.
Damp Conditions
- Effective body resistance drops drastically (from 100 kΩ to 100 Ω) under wet environment conditions
- Activities like sweating, bathing etc. lower the effective resistance of our body
- This damp condition coupled with unsafe usage of electrical appliances, would result in large current flowing through our body causing electric shock and leading to serious injury and even death.
Safety Methods
Fuses
- It protects a circuit when the electric current in the circuit becomes greater than the rating of the connecting wire due to damaged insulation, overheating of cable, or damp conditions.
- A fuse should be connected in series with a live wire and its rating should be in between the ratings of the appliance and the conducting wire. e.g.
- Rating of the fuse: 10 A
- Rating of the wire: 12 A
- Rating of the appliance: < 10 A
- Rating of the appliance < Rating of the fuse < Rating of the wire
Earthing
- If the live wire touches the case due to damage Insulation, overheating of cables or damp conditions, any person will be electrocuted if the person touches the case.
- If earthing is provided, then the current will flow from the metallic case to the earth.
- As earthing has no resistance huge current flows through the earthing wire and it melts the fuse to protect the circuit.
Circuit Breakers
Circuit breakers work like a fuse in a circuit but uses the process of electromagnetic induction to break the circuit.
