Design & Installation

Introduction to isolation and switching

This article from ELECSA provides a brief overview of isolation and switching how the terms are used in BS 7671. The term ‘isolation and switching’, as used in BS 7671, embraces four distinct concepts, each with its own particular requirements for safety. The four concepts are: isolation, switching off for mechanical maintenance, emergency switching, and functional switching. This article will only consider isolation. Summary of the four safety concepts Switching off…

The essentials of fault finding

In this video from the IET, Steven Devine, author of Student’s Guide to the IET Wiring Regulations, goes through the essentials of fault finding.

How do I determine an extraneous conductive part?

This article provides some simple guidance on how to identify extraneous conductive parts to help you avoid the unnecessary installation of protective bonding conductors. It should be appreciated that exposed metallic parts not forming part of the electrical installation are not always extraneous conductive parts as defined in Part 2 of BS 7671. Therefore, as explained in this article, to avoid the unnecessary installation of protective bonding conductors, it is important…

An introduction to earthing and bonding

Earthing and bonding are two very different, but often confused, methods of preventing electric shock. The principal of earthing is to limit the duration of touch voltages if you were to make contact with an exposed conductive part. The earth creates a safe route for the current to flow instead of causing electric shock. The purpose of bonding is to reduce the risk of electric shock if you find yourself…

An overview of cable management systems

There are a wide variety of containment systems available to organise and store cables within an installation. They tend not to be used exclusively for a particular type of wiring system, and the containment system chosen is often as much decided by the budget and practical considerations of the building it is being installed in as the cabling type itself. Fixings in cable management With such a range of cable…

Connecting equipment to a socket-outlet circuit

This article provides guidance on how to connect items of equipment to socket-outlet circuits. Socket-outlets are typically supplied by either a ring or a radial final circuit. In either case, a number of items of permanently connected equipment may also be supplied by the circuit. Such equipment should preferably be of a rating not exceeding 2 kW. The choices available to the electrician for connecting items of equipment to socket-outlet…

Installing an electrical supply to an outbuilding

This article looks at the correct procedure for installing an electrical supply to an outbuilding. Before carrying out any new or additional installation works a contractor must determine that the supply to the installation is sufficient to meet the demands of the additional load. It must also be verified that the existing earthing and bonding arrangements are adequate (Regulation 132.16 refers). Furthermore, the contractor responsible for carrying out the new…