Electrical cables used forbtemporary installations will be at risk of damage from many sources. The fact that installations are temporary means that elements of the installation, if not all, will be brought in for this purpose and then removed, possibly for reuse, upon completion.
BS 7671 makes no distinction between temporary or permanent electrical installations in terms of safety. The fact that an electrical installation is of a temporary nature does not permit a lower
standard of installation work - if anything, the requirements for temporary electrical installations
are more stringent than those for permanent installations as the operating conditions are more
onerous.
This article will look at the requirements for electrical cables for temporary electrical installations from two British Standards - BS 7671:2008 and BS 7909:2008.
Standards
What is BS 7671:2008?
BS 7671:2008 Requirements for Electrical Installations, IEE Wiring Regulations 17th Edition
What is BS 7909:2008?
BS 7909:2008 Code of practice for temporary electrical systems for entertainment and related
purposes
Scope
To begin with, let's look at the scopes of BS 7671:2008 and BS 7909:2008 and establish the
types of installations these standards cover.
The Scope of BS 7671:2008
The key point to consider is part viii of Regulation
110.1: 110.1 GENERAL
The Regulations apply to the design, erection and verification of electrical installations such as those of: (viii) construction sites, exhibitions, shows, fairgrounds and other installations for temporary purposes including professional stage and broadcast applications
Further, Regulation 110.1 states:
The Regulations are intended to be applied to electrical installations generally but, in certain cases, they may need to be supplemented by the requirements or recommendations of other British Standards or by the requirements of the person ordering the work; such cases include the following:
(xxix) Design and installation of temporary distribution systems delivering a.c. electrical supplies for lighting, technical services and other entertainment related purposes – BS 7909.
To view the full article (including Tables) from the IET's Wiring Matters Summer 2009, click on the attachment below...