Lesson Notes By Weeks and Term v5 - Grade 10

Lesson Video

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Performance objectives

• Explain 5 key workshop safety rules.
• Identify and describe the use of 5 common hand tools.
• Accurately read a multimeter for voltage, current, and resistance.
• Explain the importance of Personal Protective Equipment (PPE).
• Correctly isolate an electrical circuit.

Lesson summary

This week, we delve into the crucial aspects of workshop safety, essential hand tools, and fundamental measuring instruments used in electrical technology. Understanding and adhering to safety protocols is paramount to prevent accidents and injuries within the workshop environment. A solid grasp of tools and measuring instruments is not only necessary for accurate and efficient work but also forms the cornerstone of a successful career in electrical technology. South Africa faces numerous challenges related to electrical safety, particularly in informal settlements and aging infrastructure.

Lesson notes

Workshop Safety Workshop safety is not just a set of rules; it's a mindset. It's about being aware of your surroundings, understanding the potential hazards, and taking proactive steps to mitigate risks.

Key Safety Rules: Personal Protective Equipment (PPE): Always wear appropriate PPE. This includes safety glasses (to protect your eyes from flying debris), work boots (with steel toes for protection against falling objects and insulation against electrical shock), and gloves (insulated for electrical work and general work gloves for handling materials). In South Africa, where access to quality medical care might be limited in some areas, preventing injury in the first place is incredibly important.

Housekeeping: Maintain a clean and organized workspace. Clutter can lead to trips, falls, and difficulty finding tools. A clean environment is a safer environment. This is particularly important in smaller South African workshops where space may be limited.

Electrical Safety: Never work on live circuits unless absolutely necessary and with proper training and equipment. Always isolate the circuit by switching off the breaker or removing the fuse. Use a multimeter to verify the circuit is de-energized. Use insulated tools. Report any damaged wiring or equipment immediately. The prevalence of illegal connections in some South African communities makes understanding safe electrical practices even more critical.

Tool Safety: Use the right tool for the job. Using the wrong tool can damage the tool, the workpiece, and potentially cause injury. Keep tools in good condition and properly maintained.

Fire Safety: Know the location of fire extinguishers and how to use them. Be aware of flammable materials and ensure proper ventilation.

First Aid: Know the location of the first aid kit and how to administer basic first aid. Report all injuries, no matter how minor, to the instructor.

Isolating an Electrical Circuit: A Step-by-Step Guide Identify the Circuit: Determine the specific circuit you need to work on. Consult the circuit breaker panel or fuse box.

Switch Off the Breaker/Remove the Fuse: Locate the corresponding breaker or fuse and switch it to the "OFF" position or remove the fuse completely.

Lockout/Tagout (LOTO): If possible, use a lockout/tagout device to prevent accidental re-energization of the circuit. This involves placing a lock on the breaker and attaching a tag indicating that the circuit is being worked on. While not always feasible in all settings, understanding the principle is important.

Verify Isolation: Use a multimeter to test that the circuit is de-energized. Test between the live wire and neutral wire, and between the live wire and earth wire. Ensure the voltage reading is zero. This is a critical step!

Grounding (Earthing): Where appropriate and available, connect a temporary grounding wire to the circuit to provide an extra layer of safety. Hand Tools Various hand tools are indispensable for electrical work.

Here's a look at some common ones: Screwdrivers (Flathead and Phillips): Used for tightening or loosening screws. Insulated handles are essential for working on or near electrical circuits. Pliers (Combination, Long Nose, Side Cutting): Combination pliers are versatile for gripping, bending, and cutting wires. Long nose pliers are useful for reaching into tight spaces. Side cutting pliers are designed for cutting wires.

Wire Strippers: Used to remove the insulation from wires without damaging the conductor. Different wire strippers are designed for different wire gauges (thicknesses).

Crimping Tool: Used to crimp connectors onto wires, creating a secure electrical connection.

Hacksaw: Used for cutting metal conduit and other materials.

Tape Measure: Used for accurate measurements.

Level: Used to ensure that installations are level and plumb.

Measuring Instruments Multimeter: A versatile instrument that can measure voltage (AC and DC), current (AC and DC), resistance, and sometimes other parameters like capacitance and frequency.

Voltage Measurement: To measure voltage, 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.

Current Measurement: To measure current, connect the multimeter in series with the circuit. This requires breaking the circuit and inserting the multimeter in the path of the current flow. Select the appropriate current range (AC or DC) and a range higher than the expected current.

Important: Never connect a multimeter in current mode directly across a voltage source, as this will cause a short circuit and can damage the multimeter.

Resistance Measurement: To measure resistance, the circuit must be de-energized. Connect the multimeter leads across the resistor. Select the appropriate resistance range.