Question Three (a)A water heater is to be installed in a bathroom Specify the; (i)Mounting height for its switch. (02 marks) (ii)Rating current for its protective device. (iii)Size of the cable to b e used for its installation. (02 marks) (b)If the supply of the water heater in 3(c a), is from a two-way consumer's unit.draw it's; (02 marks) (i)Block diagram. (06 marks) (ii)Wiring diagram. (08 marks) Question Four You have been given a task to install earthing system in a new building As a trained technician; (a)List four factors you will consider when selecting a site for the above installation. (b)Describe two methods you will use to improve the conductivity of the earthing. (04 marks) (04 marks) (c)Name four materials and two tools you will need to carn out the task. (06 marks) (d)Explain a step -by-step procedur e you wil I follow to carry out the task. (06 marks) Question Five (a)Define the following terms as applied to lightning protection. (i)Down conductor (02 marks) (ii) Air termination (02 marks) (iii)Test ioint (02 marks) (iv)Zone of protection (02 marks) (b)Identify four types of buildings which require protectior from lightning. (c)with the aid of diagram show the zone of protection offered by two vertical lightning protection system. (08 marks) (04 marks)

(a)(i) 1200-1400 mm; (ii) 13 A; (iii) 2.5 mm² cable ### (b)(i) Block diagram: Consumer unit -> Protective device -> Switch -> Water heater ### (b)(ii) Wiring diagram: Shows connections as per block diagram ### (c)(a) Soil resistivity, moisture, accessibility, proximity ### (c)(b) Chemical treatment, increased depth ### (c)(c) Copper rods, grounding clamps, conductive gel, earthing wire; Shovel, multimeter ### (d) Drive rod, connect wire, measure resistance, ensure compliance ### (e)(i) Down conductor: Path to ground; Air termination: Intercepts strike; Test joint: Continuity test point; Zone of protection: Shielded area ### (e)(ii) High-rise, hospitals, schools, industrial ### (e)(iii) Diagram: Two vertical conductors showing protected zone Explanation 1. Determine Mounting Height for Switch The standard mounting height for a switch in a bathroom is typically between 1200 mm and 1400 mm from the floor. 2. Determine Rating Current for Protective Device The rating current depends on the power of the water heater. For example, a 3 kW heater at 230 V requires a protective device rated at approximately **13 A** (using I = \frac{P}{V}). 3. Determine Cable Size The cable size is determined by the current and installation conditions. For a 13 A circuit, a **2.5 mm²** cable is generally suitable. 4. Draw Block Diagram A block diagram includes the main components: consumer unit, protective device, switch, and water heater. 5. Draw Wiring Diagram A wiring diagram shows connections between the consumer unit, switch, protective device, and water heater with appropriate symbols. 6. List Factors for Selecting Earthing Site Consider soil resistivity, moisture content, location accessibility, and proximity to electrical installations. 7. Describe Methods to Improve Conductivity Use chemical treatment (e.g., adding salt) or increase electrode depth to improve conductivity. 8. Name Materials and Tools for Earthing Materials: Copper rods, grounding clamps, conductive gel, and earthing wire. Tools: Shovel and multimeter. 9. Explain Procedure for Earthing Installation Drive rod into ground, connect wire to rod, measure resistance, and ensure compliance with standards. 10. Define Lightning Protection Terms Down conductor: Path for lightning current to ground. Air termination: Component intercepting lightning strike. Test joint: Point for testing continuity. Zone of protection: Area shielded by lightning protection system. 11. Identify Buildings Requiring Lightning Protection High-rise buildings, hospitals, schools, and industrial facilities require protection. 12. Show Zone of Protection Diagram Diagram illustrates coverage area provided by two vertical conductors.