Electrical Drawing �and �Symbols

Electrical Drawing Overview

​

Symbols: Electrical drawings use standardized symbols to represent various electrical components such as switches, lights, resistors, capacitors, transformers, and more. These symbols make it easy to identify and understand the components used in the circuit.

​

An electrical drawing, also known as an electrical schematic or wiring diagram, is a visual representation of an electrical system or circuit. It provides a detailed and standardized way to communicate information about electrical components, connections, and their functions. Here is a brief overview of the key elements typically found in electrical drawings:

Lines and Wiring: Lines on the drawing represent electrical conductors (wires or cables) that connect the components. The paths and connections between components are shown using lines with specific conventions, such as straight lines for conductors and dashed lines for control or signaling connections.

Power Sources: Electrical drawings typically include symbols for power sources like batteries, generators, or mains electricity, indicating the voltage and current provided to the circuit.

Loads: Loads are devices or components that consume electrical power, such as motors, lights, heaters, or appliances. They are represented with their respective symbols.

Switches and Controls: Switches, relays, and other control devices are shown to illustrate how the circuit can be turned on or off, and how it responds to various inputs or conditions.

Connections: Junction points or connection points are marked with dots or labels to indicate where wires are connected or spliced together.

Grounding: Ground symbols (usually a downward-pointing triangle) represent grounding points in the circuit, which are essential for safety and proper functioning.

​

​

Labels and References: Each component, wire, or connection point is labeled with a unique identifier or reference designator. This helps in understanding how different parts of the circuit are related.

Notes and Annotations: Additional information, notes, or annotations may be included on the drawing to provide instructions, specifications, or important details about the circuit.

Legend and Title Block: A legend or key is often included to explain the meaning of the symbols used in the drawing. A title block at the bottom or side of the drawing typically contains information like the project name, date, scale, and the name of the designer or engineer.

Schematic Diagram vs. Wiring Diagram: There are different types of electrical drawings, including schematic diagrams and wiring diagrams. Schematic diagrams show the logical relationships and functional operation of the components, while wiring diagrams focus on the physical layout and connections of wires and components.

Electrical drawings play a crucial role in the design, construction, and maintenance of electrical systems in various applications, from residential wiring to industrial automation. They are essential for ensuring safety, troubleshooting, and understanding how electrical circuits work.

Ladder Diagram or Line Diagram

Ladder diagram are electrical diagrams that represents an electrical circuits in industries to document control logic systems.

It resemble a ladder which is why it is named ladder diagram.

There are two vertical lines; the left vertical line represents power rail (voltage source) while the right vertical line represents the ground or neutral. Each horizontal row represents a parallel circuit called rung.

A ladder diagram is simple, easier to understand and helps in troubleshooting the circuit quickly.

​

​

​

There are two rungs in the ladder digram, with lights L1 and L2. For light L1 logic is S1+S2 and for L2 Logic is S1S2

ELECTRICAL BLUEPRINTS

ELECTRICAL BLUEPRINTS PLAY AN IMPORTANT ROLE in a building’s overall architectural design. They show how wires, light fixtures, receptacles, and other parts of an industrial electrical system should be installed.

Although the lines and symbols appear complicated to an average person, trained electricians can easily figure them out. The plans come with all the keys required to decode crucial information

DIFFERENT TYPES OF INDUSTRIAL ELECTRICAL BLUEPRINTS

Blueprints are 2D drawings which are made to scale. Electrical drawings for a project include:

• Site Plan: This shows the overall location of a building as well as any external wiring.
• Floor Plans: They’re more detailed because they show the layout of electrical systems on every level of the building.
• Wiring Diagrams: These show the various physical connections and electrical circuits that will be installed.
• Schedule: It shows how long the electrical installation will last. This gives all parties involved a good idea of the pace required to finish it on time. Schedules could include information such as payment intervals, contractor’s working hours and information release dates.

​

Blueprints may be in the form of schematics or diagrams. A schematic represents the elements of a system through abstract, graphic symbols. A diagram, on the other hand, does so using more realistic pictures.

Due to subtle differences, some are referred to as schematic diagrams. They usually include details such as:

• Incoming power lines, including their rating, voltage, size, and capacity.
• Transformers, their connection, and method of grounding.
• Major switches and tiebreakers.
• Components such as batteries, generators, HVAC units, and their voltage.
• How electrical wires will be interconnected and switched.

HOW TO READ ELECTRICAL BLUEPRINTS

The following step by step instructions make electrical drawings easier to understand:

• Begin by Studying Architectural Floor Plans: Other than showing room names and the general layout, they also contain details you won’t find in the electrical plan. Once you understand what space is intended for, you should know exactly how to do the wiring.
• Analyze the Symbol Legend: Every electrical component is represented by a symbol. The legend interprets what each one means. It’s commonly found on the title page of the particular building’s plans, or on the first page showing electrical drawings.
• Review the Wiring Diagrams: These show the path taken by wires from each electrical installation all the way to the panel. A number is indicated on these wires. This reveals the breaker that every wire will be on. By understanding wiring diagrams, you can tell which items are grouped on each breaker.
• Understand Phasing Options: Phasing refers to grouping electrical components together depending on their functions. As such, lighting and equipment may be grouped on separate breakers. By studying the building layouts and intended fixtures, you’ll know which phases each item should be assigned to.
• Assess Lighting Plans: In most instances, lighting plans are separate from wiring diagrams. They show details concerning lighting fixtures across the building. They can also be interpreted using the symbol legend.
• Understand the Specification Manual: Some sets of blueprints also contain a detailed manual, also known as a spec book. It provides electrical requirements and specific materials to be used for particular jobs.

BENEFITS OF UNDERSTANDING ELECTRICAL BLUEPRINTS

Having a workforce that’s properly trained on how to read electrical blueprints is important for the following reasons:

• It Saves Time: Without a blueprint, most jobs last longer than anticipated. Electrical diagrams allow one to have an overview of the entire project and identify potential problem areas. Examples are wet spots, tight walls, and sharp corners. Being aware of their existence allows you to formulate a solution even before you get there, which saves time.
• Saves Money: A detailed plan shows you exactly what length of wire, types, and the number of components you need. Having all this information prevents shortages during installation, so you don’t have to make costly pauses to the project. Purchasing all necessary materials at once is more affordable, and contributes to an overall reduction in overhead costs.
• Improves Safety: This is arguably the biggest benefit of understanding electrical blueprints. As a technician, you can tell which parts of the building present safety hazards. This prevents workplace injury, as well as the accompanying costly delays. Potential safety hazards are sharp objects and electrocution from exposed live wires. Electrical diagrams foresee, correct, and prevent issues that might derail not just that particular installation, but the entire construction project.