Class: Senior Secondary School 1 (SS1 / SSS 1)
Term: 2nd Term
Week: 6
Age: 15 years
Duration: 45 minutes
Subject: Electrical Installation and Maintenance Work
Curriculum Theme: Technology
Previous Lesson: Practical Class on a Point Controlled by a Switch.
Topic: TWO POINTS OF LIGHT CONTROLLED BY A SWITCH
Subject Matter: wiring two points of light controlled by a switch, cable sizes and cable types for lighting circuits, wiring connection steps on a wiring board, safety checks after wiring

Specific Objectives

By the end of the lesson, pupils should be able to:

Cognitive Domain:

Define what is meant by two points of light controlled by a single switch.
Identify and describe different types of cables used for lighting circuits.
State appropriate cable sizes for lighting circuits.
Explain the step-by-step procedure for wiring two points of light controlled by a switch.
List safety checks to perform after completing a wiring connection.

Affective Domain:

Appreciate the importance of safety measures in electrical wiring.
Show willingness to follow correct wiring procedures.
Recognise the need for proper cable selection in electrical installations.

Psychomotor Domain:

Select appropriate cables for a lighting circuit.
Demonstrate the correct wiring of two points of light controlled by a single switch on a wiring board.
Perform basic safety checks on a completed wiring circuit.

Collaborate with peers during practical wiring exercises.

Reference Materials

The following resources were used in planning this lesson:

9 Years Basic Education Curriculum for Electrical Installation and Maintenance Work.
State Unified Scheme of Work for Senior Secondary School Electrical Installation and Maintenance Work.
Electrical Installation Technology by M.U. Okoro.
https://www.electricaltechnology.org/2021/01/how-to-wire-two-lights-from-one-switch.html
https://www.youtube.com/watch?v=kYJj7eC2r0A

Instructional Materials

The teacher will teach this lesson with the aid of:

Various types and sizes of electrical cables.
PVC conduits and accessories.
Nails and clips for securing cables.
A prepared wiring board with light fittings and a switch.
A multimeter for testing.

Rationale for the Lesson

This lesson helps pupils understand how to install basic lighting circuits, which is a fundamental skill in electrical installation. It enables them to apply theoretical knowledge to practical wiring scenarios and ensures they understand safety protocols in electrical work.

Prerequisite/Previous Knowledge

Pupils are expected to have basic knowledge of electrical circuits, common electrical tools, and the function of switches and light fittings from previous lessons.

Lesson Content/Board Summary

TWO POINTS OF LIGHT CONTROLLED BY A SWITCH

Meaning of Two Points of Light Controlled by a Switch

This refers to an electrical circuit where two separate light fittings (e.g., bulbs) are switched ON or OFF simultaneously using a single control switch. This arrangement is common in rooms requiring more illumination from multiple sources.

Types of Cables for Lighting Circuits

Cables used for lighting circuits are designed to carry electrical current safely to light fittings. The following are common types of cables:

PVC (Polyvinyl Chloride) Insulated Cables: These are widely used for domestic wiring. They feature copper conductors insulated with PVC material.
Twin and Earth Cables: These cables consist of two insulated current-carrying conductors (live and neutral) and one bare earth conductor, all enclosed within an outer PVC sheath.

Sizes of Cables for Lighting Circuits

Cable size refers to the cross-sectional area of the conductor, which is measured in square millimetres (mm²). The appropriate size depends on the current drawn by the circuit and the length of the cable run.

The following are common cable sizes for lighting circuits:

1.0 mm²: Suitable for light circuits with a relatively small number of light points and low power consumption.
1.5 mm²: This is a commonly recommended size for standard domestic lighting circuits, providing a good balance of current-carrying capacity and flexibility.

Steps for Wiring Two Points of Light Controlled by a Switch on a Wiring Board

Wiring two points of light controlled by a single switch involves connecting the live, neutral, and earth wires correctly to the switch and the two light fittings in parallel.

The following are the general steps:

Step 1: Plan the Layout: Determine the positions of the switch, the two light points, and the power source on the wiring board.
Step 2: Connect the Live Wire: Bring the main live wire from the power source to one terminal of the single-gang switch.
Step 3: Connect the Switched Live Wire: From the other terminal of the switch, run a wire (known as the switched live) to the live terminal of the first light fitting.
Step 4: Parallel Connection for Second Light: Connect a wire from the live terminal of the first light fitting to the live terminal of the second light fitting. This establishes a parallel connection for the live side.
Step 5: Connect the Neutral Wires: Bring the main neutral wire from the power source and connect it to the neutral terminal of the first light fitting. Then, connect a wire from the neutral terminal of the first light fitting to the neutral terminal of the second light fitting.
Step 6: Connect the Earth Wires: Connect the earth wire from the power source to the earth terminals of both light fittings and the switch casing (if it is metallic).
Step 7: Secure Cables: Use appropriate nails and clips to secure all cables neatly and firmly on the wiring board.
Step 8: Test Continuity: Before applying electrical power, perform continuity and insulation resistance tests to ensure correct connections and no short circuits.

Safety Checks After Wiring

After completing any electrical wiring, it is important to perform specific safety checks to ensure the circuit is safe and functional before applying power.

The following are essential safety checks:

Visual Inspection: Carefully check for any exposed conductors, loose connections, incorrect wiring, or damaged insulation.
Continuity Test: Use a multimeter to check for continuous electrical paths in the live, neutral, and earth circuits, ensuring there are no open circuits where connections should exist.
Insulation Resistance Test: Test for good insulation between live and earth, neutral and earth, and live and neutral to ensure there is no leakage current.
Polarity Test: Confirm that the live and neutral conductors are correctly connected to their respective terminals at the light fittings and switch.
Functionality Test (with power): Once all non-live tests are satisfactory, apply power cautiously and then test the switch operation and light illumination.

Teaching Methods/Instructional Techniques

Discussion, Lecture, Demonstration, Question and Answer, Visual Aids

Instructional Procedures

Step 1: Introduction

Time: 5 minutes
Teaching Skill: Set Induction
Teacher’s Activity: The teacher greets the pupils, reviews the previous lesson on basic electrical circuits, and asks pupils about common lighting arrangements in their homes.
Pupils’ Activity: Pupils respond to the teacher’s questions and recall previous knowledge.
Learning Point: Pupils connect to prior knowledge and are introduced to the relevance of the lesson.

Step 2: Presentation of Cable Types and Sizes

Time: 8 minutes
Teaching Skill: Explanation/Demonstration
Teacher’s Activity: The teacher displays different types of electrical cables (e.g., PVC, Twin and Earth) and discusses their uses and common sizes (1.0mm², 1.5mm²) suitable for lighting circuits. The teacher explains why specific cable sizes are chosen.
Pupils’ Activity: Pupils observe the displayed cables, ask questions for clarification, and take notes.
Learning Point: Pupils identify and differentiate cable types and sizes suitable for lighting installations.

Step 3: Explanation of Wiring Principles

Time: 7 minutes
Teaching Skill: Explanation/Illustration
Teacher’s Activity: The teacher explains the concept of two light points controlled by a single switch, drawing a simple circuit diagram on the board. The teacher emphasizes the parallel connection required for the light fittings.
Pupils’ Activity: Pupils observe the diagram, ask questions, and copy the circuit diagram into their notebooks.
Learning Point: Pupils understand the basic circuit diagram and connection principles for the lesson’s topic.

Step 4: Demonstration of Wiring Connection

Time: 10 minutes
Teaching Skill: Demonstration
Teacher’s Activity: Using the prepared wiring board, electrical cables, a switch, and two light fittings, the teacher carefully demonstrates the step-by-step wiring process for two points of light controlled by a single switch, explaining each connection point.
Pupils’ Activity: Pupils observe the demonstration closely, paying attention to the connections and safety practices.
Learning Point: Pupils observe the practical application of the wiring steps.

Step 5: Guided Practice/Pupils’ Activity

Time: 10 minutes
Teaching Skill: Practical Application/Supervision
Teacher’s Activity: The teacher divides pupils into groups or supervises individual pupils as they attempt to wire two points of light controlled by a single switch on their wiring boards, guiding them through the process.
Pupils’ Activity: Pupils wire two points of light controlled by a switch under the teacher’s supervision, applying the demonstrated steps.
Learning Point: Pupils apply learned wiring skills practically and gain hands-on experience.

Step 6: Explanation of Safety Checks

Time: 5 minutes
Teaching Skill: Explanation
Teacher’s Activity: The teacher explains the importance of performing safety checks after completing any electrical wiring. The teacher lists and briefly describes essential checks such as visual inspection, continuity test, and insulation resistance test.
Pupils’ Activity: Pupils listen attentively, ask questions, and note down the safety checks.
Learning Point: Pupils understand the necessary safety precautions and testing procedures after wiring.

Step 7: Evaluation/Review

Time: 5 minutes

Teaching Skill: Questioning/Assessment

Teacher’s Activity: The teacher evaluates the learning by asking the following questions:

Define what is meant by “two points of light controlled by a switch.”
Mention two types of cables used for lighting circuits.
State two common cable sizes suitable for lighting circuits.
List three steps involved in wiring two points of light controlled by a switch.
Explain two safety checks that must be performed after completing a wiring connection.

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Pupils demonstrate understanding of the lesson.

Step 8: Conclusion

Time: 2 minutes
Teaching Skill: Summarization
Teacher’s Activity: The teacher summarizes the key learning points of the lesson, reiterating the importance of correct wiring and safety. The teacher assigns homework, such as drawing the full circuit diagram of the lesson’s topic.
Pupils’ Activity: Pupils listen and note down the summary and homework assignment.
Learning Point: Consolidates learning and provides follow-up tasks for reinforcement.

Lesson Keywords

Parallel connection – A type of electrical circuit where components are connected across the same two points, so the voltage across each component is the same.
Live wire – The wire that carries the main electrical current from the power supply, having an alternating potential difference.
Neutral wire – The wire that completes the electrical circuit, usually maintained at or near earth potential.
Earth wire – A safety wire that provides a low-resistance path to the ground for fault currents, protecting against electric shock.
PVC cable – An electrical cable insulated with Polyvinyl Chloride, commonly used for general wiring.
Switched live – The live conductor that becomes energized only when a switch is closed, controlling the flow of current to a load.
Continuity test – An electrical test used to determine if an electrical path exists between two points in a circuit.

Differentiation

For pupils who grasp concepts quickly, the teacher can challenge them to explain the difference between series and parallel connections for lights or to troubleshoot a simple wiring fault. For pupils needing more support, the teacher can provide one-on-one guidance during the practical wiring session and offer simplified diagrams or step-by-step checklists.

Note for teachers using this lesson plan

Ensure all safety precautions are strictly followed during the practical demonstration and pupils’ activity. Verify that all tools and materials are in good working condition. Emphasize the importance of correct wire stripping, termination, and securing. Supervise pupils closely during hands-on tasks to prevent accidents and reinforce proper techniques.