Outline FIVE safety rules observed in an electrical workshop.

Question 1: Outline FIVE safety rules observed in an electrical workshop. 1. Always assume a circuit is live until proven otherwise. 2. Use appropriate Personal Protective Equipment (PPE) such as insulated gloves, safety glasses, and non-conductive footwear. 3. Never work alone on live electrical equipment. 4. Ensure all tools are in good condition and properly insulated. 5. Follow Lockout/Tagout procedures to de-energize circuits before working on them. Question 2: State FOUR common causes of electrical accidents in a workshop. 1. Faulty wiring or equipment: Damaged insulation, loose connections, or defective tools can lead to shocks or fires. 2. Lack of proper grounding: Absence of an effective ground path prevents fault currents from safely dissipating, increasing shock risk. 3. Overloaded circuits: Drawing too much current through a circuit can cause overheating, leading to insulation breakdown and fire. 4. Improper use of tools or equipment: Using tools incorrectly or for purposes they weren't designed for can result in accidents. Question 3: List FOUR types of electrical cables used in wiring installations. 1. Twin and Earth (T&E) cable: Commonly used for domestic wiring, consisting of two insulated current-carrying conductors and an uninsulated earth conductor, all within an outer sheath. 2. Armoured cable (SWA - Steel Wire Armoured): Used for underground or outdoor installations, featuring steel wire armouring for mechanical protection. 3. Flexible cable: Used for connecting portable appliances, characterized by fine strands of copper conductors for flexibility. 4. Mineral Insulated Copper Clad (MICC) cable: Known for its fire resistance and robustness, used in high-temperature or harsh environments. Question 4: State THREE factors to consider when selecting a wiring system. 1. Type of building and environment: Factors like moisture, temperature, and mechanical stress influence the choice of wiring system. 2. Cost and ease of installation: The budget and complexity of installation affect the practicality of different systems. 3. Current carrying capacity and voltage drop: The electrical load requirements determine the necessary conductor size and material to prevent excessive voltage drop. Question 5: Discuss TWO types of electrical protection devices. 1. Residual Current Device (RCD): An RCD detects an imbalance in current between the live and neutral conductors, indicating a leakage current to earth. It quickly disconnects the circuit to prevent electric shock. 2. Surge Protection Device (SPD): An SPD protects electrical equipment from voltage spikes (surges) caused by lightning strikes or switching operations. It diverts excess voltage to the earth, preventing damage to sensitive electronics. Question 6: List any FIVE electrical tools used in wiring and maintenance work. 1. Pliers (e.g., combination pliers, long-nose pliers, side cutters) 2. Screwdrivers (e.g., flathead, Phillips) 3. Wire strippers 4. Multimeter 5. Insulation resistance tester (Megger) Question 7: Explain how the following devices protect an electrical system. a) Circuit breakers Circuit breakers protect an electrical system by automatically interrupting the flow of current when an overload or short circuit occurs. They contain a bimetallic strip or an electromagnetic coil that detects excessive current, tripping a mechanism to open the circuit and prevent damage or fire. They can be reset after the fault is cleared. b) Fuses Fuses protect an electrical system by containing a thin wire or filament designed to melt and break the circuit when the current exceeds a safe level. This melting action, known as "blowing," opens the circuit and prevents damage to equipment or wiring from overcurrents or short circuits. Once a fuse blows, it must be replaced. Question 8: List FOUR types of test carried out in a newly completed installation before commissioning. 1. Continuity of protective conductors: Ensures that all exposed conductive parts are properly connected to the main earthing terminal. 2. Insulation resistance test: Verifies that the insulation between conductors and between conductors and earth is adequate to prevent leakage currents. 3. Earth fault loop impedance test: Confirms that the protective device will operate quickly enough in the event of an earth fault. 4. Polarity test: Checks that all switches and protective devices are correctly connected in the phase conductor and that the neutral is correctly identified. Question 9: Outline THREE ADVANTAGES of PVC conduit wiring systems. 1. Good insulation properties: PVC is a non-conductive material, providing excellent electrical insulation and reducing the risk of electric shock. 2. Corrosion resistance: PVC conduits are resistant to rust, corrosion, and chemical attack, making them suitable for various environments. 3. Ease of installation: PVC conduits are lightweight, easy to cut, bend, and join, which simplifies installation and reduces labor costs. Question 10: State the difference between lighting circuits and power circuits in a domestic installation. Lighting circuits are designed to supply power specifically to lighting fixtures. They typically carry lower currents and are protected by lower-rated circuit breakers (e.g., 6A or 10A). Power circuits, also known as socket outlet circuits, are designed to supply power to general-purpose socket outlets for various appliances. They typically carry higher currents and are protected by higher-rated circuit breakers (e.g., 20A or 32A).