Lesson Notes By Weeks and Term v4 - SHS 3
≈SUBSTRUCTURE AND SUPERSTRUCTURE
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≈SUBSTRUCTURE AND SUPERSTRUCTURE
Download the Lessonotes Mobile Ghana app for faster lesson access on Android and iPhone.
Subject: Applied Technology
Class: SHS 3
Term: 1st Term
Week: 15
Grade code: 3.3.2.LI.3
Strand code: 3
Sub-strand code: 3
Content standard code: 3.3.2.CS.1
Indicator code: 3.3.2.LI.3
Theme: BUILDING CONSTRUCTION TECHNOLOGY
Subtheme: ≈SUBSTRUCTURE AND SUPERSTRUCTURE
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Good day, class. In our previous lessons, we discussed the superstructure, which is the part of the building you see above the ground – the walls, floors, and roof. Today, we are going to look at one of the most important services that brings a building to life: electricity. Imagine a newly built house in your community, perhaps in Madina, Cape Coast, or Tamale. It might look complete from the outside, but without electricity, it's just a shell. You can't turn on the lights, charge your phone, watch television, or use a fan.
The "schedule of works" for electrical installation is the logical sequence of activities from planning to final power connection. We can break this down into five main phases. Phase 1: Pre-Installation (Planning & Agreement)
This is the planning stage that happens before any physical electrical work begins on-site. Agreement with Service Provider: The property owner must formally apply for an electricity connection from the Electricity Company of Ghana (ECG). This involves: Filling out application forms. Providing site plans and building permits. Signing a service agreement that outlines the terms of supply. Electrical Design: A certified electrician or electrical engineer creates a detailed wiring diagram (or layout). This plan shows the location of every light, switch, socket outlet, fan, and the consumer unit. It also specifies the type and size of cables to be used. Materials Procurement: Based on the design, a list of materials is created. This includes: Cables: Different sizes for different purposes (e.g., 1.5 mm² for lighting, 2.5 mm² for socket outlets, 6.0 mm² for cookers). Conduits/Trunking: PVC pipes or channels that protect the wires inside the walls and ceilings. Back Boxes: Metal or plastic boxes that are embedded in the wall to house switches and sockets. Consumer Unit (Fuse Box/Distribution Board): The main control panel for the building's electricity, containing circuit breakers. Earthing Materials: Copper rod, earthing cable, and clamps. Fittings and Fixtures: Sockets, switches, ceiling roses, lamp holders, etc. Phase 2: First Fix (Carcassing or Roughing-in)
This phase happens after the main blockwork is complete but before plastering. The goal is to install all the hidden components. Chasing the Walls: The electrician cuts grooves (chases) into the walls where the conduits will run. Laying Conduits and Trunking: PVC conduits are laid in the chases on the walls and on top of the concrete slab for ceiling wiring. Trunking may be used on surfaces where chasing is not possible. Installing Back Boxes: The metal or plastic back boxes for switches and sockets are fitted securely into the walls at the correct heights. For example, light switches are typically installed around 1.2 metres from the finished floor level. Consumer Unit Housing: The housing for the main consumer unit is fixed to the wall.
Why is this done before plastering? So that all the pipes and boxes can be neatly covered by the plaster, leaving a smooth wall surface. You only see the front of the back box. Phase 3: Second Fix (Wiring)