TSI

ELECTRICAL DIAGRAMS

Electrical diagrams are visual maps that show how an electrical system works and is wired. They are crucial tools for electricians and engineers during design, installation, maintenance, and troubleshooting. These diagrams use standardized symbols and lines to represent components and connections, enabling clear communication. 

Types of electrical diagrams

Different types of diagrams serve specific purposes, providing varied levels of detail. 

• Schematic diagram:

This diagram focuses on the functional logic of a circuit using abstract symbols, not the physical layout. It shows the connections between components to help understand how the circuit works, making it ideal for troubleshooting.

• Single-line diagram (SLD):

Also called a one-line diagram, this offers a simplified overview of an electrical power system. It uses a single line to represent multiple conductors (like a three-phase system) and shows how major components like transformers and circuit breakers are interconnected.

• Wiring diagram:

This shows the physical layout and connections of an electrical system. It provides details on wire colors, sizes, and the relative positions of components, which is critical for installation and repair.

• Ladder diagram:

A specialized schematic often used for industrial control logic, it resembles a ladder with two vertical rails (power supply) and horizontal rungs (control circuits). It is used to document how electromechanical switches and relays are interconnected.

• Electrical floor plan:

This is an architectural drawing that shows the location of electrical fixtures, outlets, and switches within a building's physical layout. It is essential for new construction or remodeling.

• Riser diagram:

Illustrates the physical layout of electrical distribution in a multi-level building using a single line. It shows the path of electrical distribution from the point of entry to each floor and sub-circuit. 

 

How to read electrical diagrams

To correctly interpret an electrical diagram, follow these general steps: 

1. Start with the legend:

Diagrams use standardized symbols and abbreviations, which are explained in a key or legend. Study this first to understand what each symbol represents.

2. Follow the flow:

For schematics, read from left to right and top to bottom, following the path of the current from the power source to the components.

3. Trace the path:

Identify the power source and trace the circuit through switches, fuses, and loads. Wires that are connected are often indicated with a small dot at their intersection, while those that cross without a connection have no dot.

4. Pay attention to details:

Look for wire tags, component labels (e.g., R1 for resistor 1), and notes that provide specific details on components and their values. 

 

Electrical diagrams and trunking systems

Electrical diagrams are used to detail the specific requirements for a trunking installation. 

• Single-line diagrams

Might show the main trunking runs and how power is distributed to different areas of a building.

• Wiring diagrams 

Would detail the actual cables being laid in the trunking, including segregation requirements for different types of circuits (e.g., power vs. data).

• Floor plans

Would show the physical route of the trunking system along walls, ceilings, or floors.