Lesson Notes By Weeks and Term v5 - Grade 12

Lesson Video

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Performance objectives

• Identify and draw standard SANS symbols for plumbing and drainage.
• Draw a schematic layout of a cold water supply system.
• Sketch a simple electrical layout for a room.
• Describe the function of key components in a sewage drainage system.
• Differentiate between single-line and double-line representations.

Lesson summary

Building services are the systems within a building that make it habitable and functional. This includes essential infrastructure like plumbing, electrical, and ventilation systems. Detailing in civil drawings involves representing these services accurately and comprehensively so that contractors can install them correctly. In South Africa, understanding these services is crucial for ensuring the safety, health, and comfort of occupants, especially considering factors like water scarcity and energy efficiency. From designing RDP housing to planning complex commercial buildings, EGD skills in building services directly contribute to improving living standards and driving economic development.

Lesson notes

2.1 Plumbing Systems Plumbing systems deliver potable water and remove wastewater. They are critical for hygiene and sanitation. In South Africa, water conservation is paramount, so understanding efficient plumbing design is crucial.

Potable Water Supply: This system brings clean water into the building. It typically includes a connection to the municipal water supply, a main water pipe, distribution pipes, stop cocks, and fixtures like taps, showers, and toilets. In areas with water shortages, rainwater harvesting systems might also be included.

Hot Water Supply: A geyser (electric or solar) heats water for showers, baths, and sinks. Proper insulation of hot water pipes is essential to minimize heat loss and save energy. Solar water heaters are increasingly common and even mandated in some new buildings in South Africa to reduce electricity consumption.

Drainage System: This system removes wastewater (sewage and greywater). It consists of waste pipes, soil pipes, traps (to prevent sewer gases from entering the building), ventilation pipes (to allow air circulation and prevent siphoning), and a connection to the municipal sewer or a septic tank.

Symbols: Standard symbols are used to represent plumbing fixtures and components on drawings.

Examples include: WC (Water Closet/Toilet) WHB (Wash Hand Basin) S (Sink) SH (Shower) G (Geyser) IC (Inspection Chamber) 2.2 Electrical Systems Electrical systems provide power for lighting, appliances, and other equipment. Safety is a major concern, so electrical installations must comply with strict regulations.

Electrical Supply: The system starts with a connection to the municipal power grid. The electricity passes through a meter and a distribution board (DB), which contains circuit breakers to protect against overloads and short circuits.

Wiring: Electrical wiring distributes power to various outlets, lights, and appliances. The wiring is typically concealed within walls or ceilings in conduits (protective pipes).

Lighting: Lighting fixtures provide illumination. Different types of lighting are used for different purposes, such as general lighting, task lighting, and accent lighting. Energy-efficient LED lighting is increasingly popular in South Africa to reduce electricity consumption.

Socket Outlets: Socket outlets provide power for appliances and equipment. They are typically rated at 16 amps or 20 amps.

Switches: Switches control the flow of electricity to lights and other devices.

Symbols: Light Fitting (Circle with cross) Single Switch (Line with a short perpendicular line) Double Switch (Line with two short perpendicular lines) Socket Outlet (Circle with two or three small lines indicating prongs) Distribution Board (Rectangle with 'DB' inside) 2.3 Sewage Drainage Systems Sewage drainage systems are specifically designed to remove wastewater containing human waste. These systems are critical for public health.

Soil Pipes: These pipes carry waste from toilets.

Waste Pipes: These pipes carry waste from sinks, showers, and basins (greywater).

Traps: U-shaped or P-shaped bends in the pipes that hold water to prevent sewer gases from entering the building.

Ventilation Pipes: Vertical pipes that extend above the roofline to allow air circulation within the drainage system and prevent siphoning of water from the traps.

Inspection Chambers (Manholes): Access points in the drainage system for inspection and maintenance. 2.4 Single-Line vs. Double-Line Representation Single-Line Representation: Used for schematic layouts and concept drawings. Pipes and conduits are represented by a single line with annotations indicating their size and material. This simplifies the drawing and makes it easier to understand the overall system layout.

Double-Line Representation: Used for detailed drawings where the exact size and position of pipes and conduits are critical. The pipes and conduits are represented by two parallel lines, accurately showing their diameter.

Example 1: Drawing a Cold Water Supply Layout Imagine you need to draw the cold water supply layout for a small RDP house. The house has a kitchen sink, a bathroom sink, a toilet, and a shower. The water supply enters the house at one point.

Start with the Main Supply: Draw a single line representing the main water pipe entering the house. Label it "20mm Main Water Supply." Route the Pipe: Show the pipe branching out to the different fixtures. Use T-junctions to indicate where the pipe splits.

Add Fixtures: Draw the symbols for the kitchen sink (S), bathroom sink (WHB), toilet (WC), and shower (SH).

Connect the Pipes: Connect the pipes to the fixtures.

Add Stop Cocks: Indicate stop cocks near each fixture to allow for isolation during repairs. Use a small circle symbol for the stop cock.

Label Pipes: Label the pipes with their diameter (e.g., 15mm).

Example 2: Drawing a Simple Electrical Layout Consider drawing the electrical layout for a classroom.