DIY Doctor

Main navigation

cable calculation

Postby maveric » Wed Jan 21, 2009 5:06 pm

:? could anyone one tell me in easy to understand terms how to calculate the cable and breaker size , including cf's and volt drop, i have a copy of BS7671 IEE Wiring Regs but i am struggling to get my head around the long calculation to reach Zs, fault current and minimum csa of cpc .
Rank: Labourer
Progress to next rank:
Posts: 4
Joined: Wed Jan 21, 2009 4:16 pm


Simply Build It

Postby SparkyPaul » Wed Jan 28, 2009 7:45 pm

Start by calculating the design current
Select an MCB which is higher than that of the design current
Apply the correction factors to the size of the MCB
Use this to select a cable from the appendix of the regs
Verify the volt drop doesn't exceed the maximum allowed
If the cpc is the same size as the lives then it is fine
If the cpc is smaller then you can check it with regulation 543.1 in the regs.
Rank: Apprentice
Progress to next rank:
Posts: 18
Joined: Wed Jan 28, 2009 7:18 pm

Postby sparx » Wed Jan 28, 2009 8:00 pm

this has been answered at length on another post on sunday 25th!
this is a duplicate post please look back
Rank: Project Manager
Posts: 2166
Joined: Wed Mar 21, 2007 8:33 pm
Location: The fifth continent.

Display posts from previous
Sort by
Order by

  • DIY How to Project Guides
  • DIY how to tutorial projects and guides - Did you know we have a DIY Projects section? Well, if no, then we certainly do! Within this area of our site have literally hundreds of how-to guides and tutorials that cover a huge range of home improvement tasks. Each page also comes with pictures and a video to make completing those jobs even easier!

  • Related Topics