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What is Electrical System Design?

Electrical System Design refers to the design of various electrical systems. It is not only confined to power system transmission & distribution but also encapsulates lighting equipment, electronic equipment, and voice & data communication systems.

In this article, I will briefly introduce you to the steps/requirements for an electrical system design in Oil & Gas companies. It’s worth mentioning here that these requirements are not restricted to oil & gas sector as most of them also apply to Construction, Cement & Fertilizers industries. In short, a basic requirement for an electrical system design.

Design Must Be Economical – An Essential Requirement Of Every Project

Assuming that everyone is familiar with the concept of how a project is awarded to oil & gas consultants/design companies, I will concentrate more on how the design process starts/executes. The basic mechanism is that the companies/consultants prepare proposals based on assumptions, estimations and calculations then go for bidding the project to clients. The project is ultimately awarded to the company that have a design and cost suitable for the client.

Electrical Power System design may occur in two stages:

  • Basic Design
  • Detail Design

Basic Design is based on rough estimation and calculation which most commonly includes survey, assumption and experience based decisions.

Detail Design provides precisely formulated documents  and drawings to execute the project based on calculations and software studies.

Documentation covers all the aspects of the electrical power system design of a plant and it varies from project to project. However, below are the few basic documents required by every project.

  • Load List
  • Cable Sizing Calculation

Other documents may include

  • Lighting Distribution Board Schedule
  • Lighting and small power cable calculation
  • Utility Distribution Board Schedule
  • Bill of Materials (Procurement Related)

Software Studies related to electrical power system design and analysis are considered to be essential part of every project and include the following.

  • Load Flow Analysis
  • Short Circuit Calculation
  • Motor Starting Study
  • Device Coordination Study

ETAP (Electrical Transient and Analysis Program) is the most commonly used software package for all the above studies.

Similarly Lux Level Calculation for lighting is also an important factor. DIALux software package is used for this purpose but other packages are also available.

Drawing usually explains the interconnection of different systems but according to client’s requirement, the number of these drawings may vary. Some common types are as follows.

  • Single Line Diagram
  • MCC Wiring Schematic
  • MCC Elevation Layout
  • Electrical Cable Routing Layout
  • Electrical Tray/Ladder Layout
  • Lighting Layout
  • Lighting Reticulation
  • Lighting Distribution Board layout
  • Lighting DB Circuit Diagram
  • UPS Wiring Schematic

AUTOCAD is the best software package for designing all these drawings. It is in fact used by most of the companies worldwide and professional draftsmen are hired for this purpose.

It is also important to note that these documents and drawings are not always required, depending upon the client’s requirements and scope of the project, demand may vary.


Nouman Mustafa Malik has completed BSc. Electrical Engineering. He is presently associated with one of the leading multinational Oil & Gas Company as Electrical & Instrumentation Design Engineer at Lahore, Pakistan. He is a Freelancer Design Engineer. He is a Technical Blogger and familiar with Urdu & English languages. He wants to share his experience & knowledge and help technical personnel to find suitable environment for solutions.

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