Lesson Notes By Weeks and Term v5 - Grade 10

Lesson Video

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Performance objectives

• Identify and use hand tools safely.
• Describe the function of multimeters and clamp meters.
• Accurately measure voltage, current, and resistance.
• Explain the importance of Personal Protective Equipment (PPE).
• Apply first aid for electrical shock and burns.

Lesson summary

This week, we delve deeper into workshop safety, tools, and measuring instruments vital for any aspiring electrical technician in South Africa. Electrical work is inherently dangerous if safety protocols aren't strictly adhered to. Understanding the correct usage and limitations of hand tools and measuring instruments is not just about passing exams; it's about preventing serious injuries, protecting lives, and ensuring quality workmanship in the electrical industry. Imagine an electrician in a rural community installing solar panels without proper safety equipment or correct voltage readings. The consequences could be disastrous.

Lesson notes

2.1 Workshop Safety Recap & Expansion: Last week, we introduced basic workshop safety. This week, we build on that foundation. Remember that a clean and organized workspace is a safe workspace. Always clean up spills immediately. Report any damaged tools or equipment to your teacher or supervisor.

Lockout/Tagout Procedures: In South Africa, as mandated by the Occupational Health and Safety Act, lockout/tagout (LOTO) procedures are crucial when working on electrical equipment. LOTO involves isolating the electrical supply to a piece of equipment before working on it and then attaching a lock and tag to the energy isolating device. The tag identifies the person who locked out the equipment and the reason for the lockout. Never remove someone else's lock or tag.

Example: Imagine repairing a faulty distribution board. Before you touch anything, disconnect the power supply at the main circuit breaker, attach a lock to the breaker, and place a tag with your name and the date. This prevents anyone from accidentally re-energizing the circuit while you're working.

Emergency Procedures: Know the location of the first aid kit, fire extinguisher, and emergency contact numbers. In the event of an electrical shock, immediately disconnect the power supply if it is safe to do so. Call for help and administer first aid. We'll discuss first aid for electrical shock in more detail later. 2.2 Hand Tools: Selection, Usage, and Safety Screwdrivers (Slotted, Phillips, Pozidriv): Choose the correct screwdriver size and type for the screw. Using the wrong screwdriver can damage the screw head and potentially slip, causing injury. Ensure the screwdriver handle is insulated and in good condition.

Example: When securing a switch in a wall box, use an insulated Phillips head screwdriver of the correct size. Pliers (Combination, Long Nose, Side Cutting): Pliers are used for gripping, bending, and cutting wires. Use insulated pliers specifically designed for electrical work. Never use pliers to cut live wires unless they are specifically rated for that voltage. Side cutting pliers are often called "dykes".

Example: Use combination pliers to bend the end of a wire to create a hook for connecting it to a terminal. Use side cutting pliers to trim excess wire length.

Wire Strippers: Wire strippers are essential for removing insulation from wires without damaging the conductor. Use the correct size stripping hole for the wire gauge.

Example: Stripping the insulation from a 2.5mm 2 electrical wire requires the correct size stripping hole to avoid nicking the copper conductor. A nicked conductor will reduce the wire's current-carrying capacity and potentially create a fire hazard.

Crimping Tools: Crimping tools are used to attach connectors to wires. Ensure you use the correct crimping die for the connector size and type. A properly crimped connection provides a secure and reliable electrical connection.

Example: Crimping a spade connector onto the end of a wire for connecting to a terminal block.

Electrical Tape: Use electrical tape to insulate wire connections and protect them from moisture and abrasion. Use high-quality electrical tape that is rated for electrical applications.

Example: Insulating a joint between two wires that have been spliced together.

Fish Tape (Draw Wire): Used to pull wires through conduits. 2.3 Measuring Instruments: Multimeters and Clamp Meters Multimeter: A multimeter is a versatile instrument that can measure voltage (V), current (A), and resistance (Ω). It is an essential tool for any electrical technician.

Voltage Measurement: Always connect the multimeter in parallel with the circuit element you want to measure the voltage across. Select the appropriate voltage range (AC or DC) and a range higher than the expected voltage to avoid damaging the multimeter.

Example: Measuring the voltage across a light bulb in a circuit. If you expect 220V AC, select the 750V AC range on the multimeter (or the next highest range available).

Current Measurement: Always connect the multimeter in series with the circuit. Break the circuit and insert the multimeter in line. Select the appropriate current range (AC or DC) and a range higher than the expected current. Never connect a multimeter in parallel when measuring current, as this will cause a short circuit and potentially damage the multimeter and the circuit.

Example: Measuring the current flowing through a resistor. Break the circuit, connect the multimeter in series with the resistor, and select the appropriate current range.

Resistance Measurement: Always disconnect the circuit from the power supply before measuring resistance. Ensure that the component you are measuring is isolated from the rest of the circuit.

Example: Measuring the resistance of a resistor. Disconnect the resistor from the circuit and connect the multimeter leads to the resistor terminals.

Clamp Meter: A clamp meter measures current without breaking the circuit.