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Cable Sizing

Course Structure  
Learning Outcomes

Course Fees
Corporate Offerings 

Designed by a collaborative group of key building services consultancies and contractors, this CIBSE Online Learning module offers a practical, flexible and convenient alternative to face to face courses. This unit allows you to take a coordinated journey through an individual topic or a series of topics, finishing by testing your knowledge with interactive activity pages.

Cable Sizing Feedback

Course Structure

This course employs a cable sizing template that acts as a visual checklist for the necessary design decisions and calculations to meet the requirements of BS 7671:2018. The Cable Sizing Template can be used as a stand-alone design sheet, or it can be used to inform the process, enabling a more cost effective use of commercial cable-sizing software with greater understanding of the design methodologies that they are typically based around.

Make your way through this course at your own pace with the following:  

  • Cable Sizing Topics
  • Additional Resources
  • Four Activity Pages
  • CPD Certificate on completion

This course covers: 

  • Welcome
  • Introduction
  • Cable Sizing Overview
  • Protection Against Overload
  • Protection Against Short-Circuit
  • Fault Protections
  • Voltage Drop
  • Network Analysis
  • Busbar and Busbar Trunking
  • Case Studies
  • Conclusion

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CIBSE online learning courses are suitable for those wishing to enhance and support their current knowledge base, as well as graduates within an engineering discipline. 
Each unit has been peer reviewed and tested through this group. The units allow students to take a coordinated journey through an individual topic or a series of topics. The units form the backbone of several corporate training schemes.


Learning Outcomes 

  • To provide a best-practice, ‘structured’ approach to cable sizing
  • To enable you to demonstrate compliance with ISO9001 and other quality assurance measures
  • To enable you to provide an audit trail of the design/decision process
  • To provide you with a understanding to assess the impact
  • (If any) on conductor sizes for last-minute and/or on-site design changes
  • To enable you to ‘spot-check’ computer designed solutions

Once completed, this module will allow users to design cables to meet the requirements of BS 7671:2018 (Requirements for electrical installations, IET Wiring Regulations, Eighteenth Edition). Structured around a Cable Sizing Template (CST) – which acts jointly as both a design check-list and a record sheet – users are guided towards an optimal design solution. The four necessary parameters of: protection against over-current, protection against short-circuit, protection against electric shock and voltage drop can each be independently assessed either for a complete design process or for spot comparison against software output. 

In addition, although in many cases cable sizing calculations will be undertaken by the use of proprietary software, completion of the module will give the users of such packages a greater understanding of the calculations the software is undertaking, thereby enabling them to utilise such software more effectively. The principle being that in order to effectively understand and use any software package, you first have to be able to undertake the calculations by hand.


Course Fees 

  • CIBSE Member Rate: £255 + VAT
  • Standard Rate: £300 + VAT

Corporate Offerings 

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Purchase online learning training for your employees by choosing from the full list of CIBSE Corporate training.
You will benefit from being able to allocate training and monitor your employees’ learning performance remotely. Book an online learning tour to view those benefits and our digital learning platform.

In addition, you can now estimate the costs of purchasing our modules and courses with our new corporate training for online learning.

To get a quote, simply email with the name of the training, contact details and number of employees.

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