Earths / Protective Conductors are the most important conductor on any installation and that’s why it’s also one of the most important Chapters in the 17th Edition.
Chapter 54 Earthing Arrangements and Protective Conductors.
From the various supply arrangements; TN-S, TN-C-S and TT which describe how an installation is earthed through to what can be used as an earth electrode, earth conductor and a protective conductor as well as also what sizes should be used.
Points of Interest
542.2.3 “What can be used as an earth electrode” and 524.2.6 “What can’t be used”
Protective conductor sizes 543.1.1(i) calculated see 543.1.3 or (ii) selected have look at 534.1.4 and Table 54.7
Main protective bonding conductor sizes. For a TN-S and TT earthing system see 544.1.1 and for a TN-C-S (PME) use Table 54.8
Supplementary bonding – it’s 4mm unprotected or 2.5mm if mechanically protected.
Getting stuck into Chapter 54 is not just important for your 17th Edition exam but it’s a vital part of your responsibilities as an electrician to ensure that every bonding and protective conductor in an installation is correct as they form a vital part of the method of protection – Automatic Disconnection of Supply and thus saves lives.
It all starts on page 161 BS7671:2008+A3:2015
Paul Moseley (Electrician/Tutor)
“Study When You Want and Pass When You Are Ready” www.the-Regs.co.uk