Lesson Notes By Weeks and Term v5 - Grade 10

Lesson Video

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Performance objectives

• Identify workshop hazards and safety precautions.
• Identify and describe the function of basic hand tools.
• Use a multimeter to measure voltage, current, and resistance.
• Demonstrate how to safely isolate a circuit.
• Select the correct tool for a specific task.

Lesson summary

Welcome to Electrical Technology! This subject is crucial for understanding the electrical world around us, from the lights in our homes to the complex systems powering South African industries. This week, we're diving into workshop safety, essential tools, and measuring instruments. This knowledge is not just academic; it's about keeping you safe, building practical skills, and opening doors to future careers in electrical engineering, renewable energy, and related fields, all of which are growing sectors in South Africa. A strong understanding of safety and tools will ensure you can work competently and safely in any electrical environment.

Lesson notes

Workshop Safety Safety is paramount in any electrical workshop. Ignoring safety rules can lead to serious injury or even death.

Here are some key hazards and precautions: Electrical Shock: This is the most significant hazard. Contact with live wires can cause burns, muscle spasms, cardiac arrest, and death.

Precautions: Always isolate the circuit before working on it. Use insulated tools and wear appropriate personal protective equipment (PPE) such as insulated gloves and safety glasses. Never work in damp or wet conditions. Regularly inspect tools and equipment for damage. Earth (ground) all equipment.

Burns: Can be caused by electrical arcs, overheating components, or contact with hot surfaces.

Precautions: Wear appropriate PPE. Use heat-resistant gloves when handling hot components. Ensure proper ventilation when soldering.

Cuts and Abrasions: Can be caused by sharp tools, wires, or equipment.

Precautions: Use sharp tools correctly and carefully. Wear safety glasses to protect your eyes from flying debris. Use work gloves. Keep the work area tidy.

Fire Hazards: Electrical faults can cause fires. Flammable materials should be stored safely away from electrical equipment.

Precautions: Have a fire extinguisher readily available and know how to use it. Ensure proper ventilation. Store flammable materials in designated areas. Regularly inspect electrical wiring and equipment for damage.

Fumes and Gases: Soldering and other processes can release harmful fumes.

Precautions: Work in a well-ventilated area. Use a fume extractor when soldering. Wear a respirator if necessary.

Trips and Falls: Cluttered workspaces can lead to trips and falls.

Precautions: Keep the work area clean and tidy. Ensure adequate lighting. Be aware of your surroundings.

Example of Circuit Isolation: Let's say you need to replace a faulty light switch in a circuit.

The following steps are crucial: Identify the Correct Circuit: Locate the circuit breaker or fuse that controls the light switch. You might need to test other lights or outlets on the circuit to confirm.

Switch OFF the Breaker/Remove Fuse: This is the most important step. Physically switch the breaker to the "OFF" position or remove the fuse.

Lockout/Tagout (LOTO): If available, use a lockout device to prevent the breaker from being accidentally switched back on. If a LOTO device isn't available, clearly tag the breaker indicating "Do Not Switch On - Work in Progress." Test for Voltage: Use a multimeter to confirm that the circuit is de-energized. Connect the multimeter leads to the switch terminals and verify that there is no voltage present. This step is vital to ensure the circuit is truly safe. NEVER assume the circuit is dead. Basic Hand Tools Screwdrivers (Flathead and Phillips): Used for tightening or loosening screws. Select the correct size screwdriver for the screw to avoid damaging the screw head. Pliers (Combination, Long-Nose, Side-Cutting): Used for gripping, bending, and cutting wires. Combination pliers are versatile, long-nose pliers are good for tight spaces, and side-cutting pliers are used for cutting wires cleanly.

Wire Strippers: Used to remove insulation from wires without damaging the conductor.

Crimping Tool: Used to crimp connectors onto wires.

Hammer: Used for driving nails or other fasteners (less common in electrical work but still useful).

Adjustable Wrench (Spanner): Used for tightening or loosening nuts and bolts.

Hacksaw: Used for cutting metal conduit or other materials.

Tape Measure: Used for measuring distances.

Spirit Level: Used for ensuring surfaces are level.

Files: Used for smoothing rough edges.

Allen Keys (Hex Keys): Used for tightening or loosening Allen head screws.

Measuring Instruments: The Multimeter The multimeter is an essential tool for any electrical technician. It can measure voltage (V), current (A), and resistance (Ω).

Voltage (V): Measures the electrical potential difference between two points in a circuit. Measured in Volts.

Current (A): Measures the flow of electrical charge through a circuit. Measured in Amperes (Amps). Resistance (Ω): Measures the opposition to the flow of current in a circuit. Measured in Ohms. Using a Multimeter to Measure Voltage (DC): Select the Voltage Range: Turn the multimeter dial to the DC voltage (VDC or ---V) range that is higher than the expected voltage you are measuring. If you are unsure, start with the highest voltage range and work your way down to a more precise range. For example, if you are measuring a 12V battery, select the 20V range if available, or a higher range.

Connect the Leads: Insert the black lead into the "COM" (common) terminal and the red lead into the "V" terminal.

Connect to the Circuit: Connect the leads in parallel with the component or circuit you are measuring. For example, if you are measuring the voltage across a resistor, place the red lead on one side of the resistor and the black lead on the other side.