Earthing design in electrical networks and installations

Importance of earthing design

Earthing design in electrical networks and installations is important to ensure correct operation. It also serves a vital safety role – facts which are amply reinforced in legislation and codes of practice. Most engineers in power supply, buildings services and instrumentation will need to become familiar with the subject during their career.

This may arise when investigating equipment failure, unsatisfactory power quality, interference or ensuring that safe conditions are provided for staff working on electrical equipment. Despite an obvious need, earthing is barely covered during engineering degree courses. It is also difficult to obtain up to date, reliable information on the subject.

For example, if one consults books on building services or electrical substation design, the chapter on earthing is almost inevitably a small one – a situation which is almost reversed when one examines the standards which apply.

The book starts by discussing:

• The reasons for earthing
• The alternative types of earthing system and
• Legislation

The coverage has been broadened to include typical earthing system designs for a range of applications and the problems which can be anticipated.

The main focus of the book is towards the earth electrode, i.e. that part of the earthing system which is installed in the ground. An efficient earth electrode is required for lightning protection, domestic electrical wiring and large industrial or power plants.

The general installation and design aspects for the earth electrode are similar throughout these applications, although the overall earthing system design will differ significantly amongst them.