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Cable Sizing

Key Areas
Course Content
Learning Outcomes
Who Should Attend

Course Fees
Getting Setup
How to Purchase 


Purchase Cable Sizing Now


Key Areas

Welcome to the Cable Sizing Course. 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.

This course is worth 7 CPD hours


Course Content 

  • Cable Sizing Introduction             
  • Cable Sizing Overview   
  • Protection Against Overload     
  • Protection Against Short-circuit
  • Fault Protection   
  • Voltage drop     
  • Network Analysis           
  • Case Studies      

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.

Who Should Attend 

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.


Course Fees 

  • Membership Rate: £270 (£324 inc VAT)
  • Standard Rate: £300 (£360 inc VAT)


Getting Setup

New User
If you are a new user to CIBSE and would like to purchase an online learning course please contact us on 020 8772 3660 or email us at to get you started. 

Alternatively, please follow the set up instructions below:
To set up the MyCIBSE Portal create a username from your desired email address and create a password. Then login to the Online Learning Portal with the same credentials as used to create your MyCIBSE Portal.

Once you have successfully logged in to both portals, please contact us on 020 8772 3660 or email us at to activate your account.

Existing User
If you are already a user of MyCIBSE but have not yet accessed our Online Learning Portal, please login to the Online Learning Portal with the same credentials as used for your MyCIBSE Portal. 

Once you have successfully logged in, please contact us on 020 8772 3660 or email us at to activate your account.

How to Purchase

  • ​Online: Log into your MyCIBSE account to purchase your desired course. Courses can be purchased by selecting the tab 'Online Learning' then by finding your course under one of the three topics mentioned above. This is by method of Credit / Debit card only.

  • For corporate rates please contact the training team on

Corporate subscribers, please contact the training team at