Lesson Notes By Weeks and Term v4 - SHS 2
ELECTRICAL SYSTEMS DESIGN
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ELECTRICAL SYSTEMS DESIGN
Download the Lessonotes Mobile Ghana app for faster lesson access on Android and iPhone.
Subject: Applied Technology
Class: SHS 2
Term: 2nd Term
Week: 13
Grade code: 2.5.1.LI.2
Strand code: 5
Sub-strand code: 1
Content standard code: 2.5.1.CS.1
Indicator code: 2.5.1.LI.2
Theme: ELECTRICAL AND ELECTRONIC TECHNOLOGY
Subtheme: ELECTRICAL SYSTEMS DESIGN
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Welcome, learners! In Ghana today, from the bustling markets of Accra to the newly developing communities in every region, electricity is essential for our daily lives. The safe and reliable installation of electrical systems in our homes, schools, and offices depends on skilled electricians using the correct tools for the job. Using the wrong tool can lead to poor connections, damage to materials, and even dangerous situations like electrical shocks or fires. This lesson will introduce you to the fundamental tools and equipment every professional electrician must have.
The tools used for house wiring can be grouped into several categories. Understanding these categories helps in organising your toolbox and selecting the right tool quickly. A. Hand Tools (Cutting, Gripping, and Stripping)
These are the most frequently used tools for manipulating wires and cables. Combination Pliers: Description: A multi-purpose tool with a flat, serrated jaw for gripping, a circular toothed section for gripping round objects like pipes, and a sharp cutting edge at the base of the jaws. Function: Used for gripping, twisting, bending, and cutting wires. It's the "all-rounder" or "general-purpose" tool in an electrician's pouch. Example: When joining two 2.5mm² wires, you use the pliers to twist them together tightly before putting on a connector. Side-Cutting Pliers (Side Cutters or Diagonal Cutters): Description: These pliers have sharp, diagonal jaws designed exclusively for cutting. Function: Used for making clean cuts through copper and aluminium wires. They are not designed for gripping or twisting. Using them on hard materials like steel nails will damage the cutting edge. Example: Trimming the excess length of wires inside a junction box before connecting them to a switch or socket. Long Nose Pliers (Needle Nose Pliers): Description: Pliers with long, tapering jaws. Function: Ideal for working in tight spaces where fingers and combination pliers cannot reach. Used for bending small loops in wires (e.g., for terminal screws) and holding small components. Example: Reaching into a deep electrical box to retrieve and position a wire. Wire Stripper: Description: A tool with multiple pre-sized holes or an adjustable blade for cutting through the insulation of a wire without damaging the copper conductor inside. Function: To remove the outer plastic insulation from electrical wires. This is the professional and safest way to prepare a wire for connection. Example: To connect a wire to a light switch terminal, you must first use a wire stripper to remove about 1cm of insulation from the end of the wire. Using a knife or your teeth is dangerous and can damage the wire, leading to a fire hazard. Screwdrivers (Flathead and Phillips/Star): Description: Tools for driving or removing screws. Electrician's screwdrivers must have insulated handles to protect against electric shock. Function: Flathead (Minus): For screws with a single slot. Phillips (Star/Plus): For screws with a cross-shaped slot. Example: Used to fix sockets, switches, and consumer units (fuse boxes) to the wall boxes and to tighten terminal screws that hold wires in place. B. Measuring and Testing Equipment
These tools are crucial for accuracy and safety. Never work on a circuit without first testing it. Multimeter (Digital or Analogue): Description: An indispensable electronic measuring instrument that combines several measurement functions in one unit. Functions: Voltmeter (V): Measures voltage (AC/DC). Used to check if a circuit is live and to ensure the voltage is correct (e.g., ~230V in Ghanaian sockets). Ohmmeter (Ω): Measures resistance. Used to check for continuity (i.e., if there is a complete path for current to flow, like checking if a fuse is blown or a wire is broken). Ammeter (A): Measures current. Used for advanced diagnostics. Example: Before changing a faulty socket, an electrician uses the multimeter (set to AC Volts) to confirm that the power to that socket is truly OFF at the consumer unit. Voltage Tester (Neon Tester or Test Light): Description: A simpler, pen-like device with a small light (neon bulb) that glows when it detects voltage. Function: A quick and easy way to check for the presence of AC voltage in wires, sockets, or terminals. It's a fundamental safety tool. Example: An electrician touches the tip of the tester to a wire. If the light glows, the wire is live, and it is not safe to touch. Measuring Tape: Description: A flexible ruler used for measuring distances. Function: Used for measuring the length of conduit runs, heights for switch and socket placement, and cutting wires to the correct length. Accuracy here prevents waste of materials. C. Installation and Fishing Tools
These tools are used for the physical installation of conduits, boxes, and cables. Draw Wire (Fish Tape): Description: A long, flexible but rigid strip of steel or fibreglass, often coiled inside a reel. Function: Used to pull wires and cables through long runs of conduit (pipes) that are embedded in walls or ceilings. How it works: You push the fish tape through the empty conduit from one box to another. Then, you securely attach the electrical wires to the hook at the end of the tape and pull it back, drawing the wires through the conduit. Hacksaw: Description: A fine-toothed saw used for cutting metal and plastic. Function: In wiring, it is primarily used for cutting PVC or metal conduit pipes to the required lengths. Hammer (Claw Hammer): Description: A standard hammer with one flat face for striking and a claw for pulling out nails. Function: Used to fix cable clips to walls (for surface wiring) and to gently tap mounting boxes into place. D. Personal Protective Equipment (PPE)