There are a number of measures to protect against electric shock. This article, which is the first part of two, looks at summarising these protective measures applied to Special Installations or Locations as defined in Part 7 of the 17th Edition of the IEE Wiring Regulations (BS7671:2008). In particular this article looks at Sections 701 to 711.
One of the fundamental principles for electrical installations is protection for safety (Section 131) in which Regulation 131.2, Protection against electric shock, requires protection to prevent
a person or livestock coming into contact with live parts by the provision of basic protection (direct contact) as well as fault protection (indirect contact) to prevent an electric shock when an
exposed conductive part becomes live due to a fault.
The technical requirements of this principle are dealt with in Part 4 of the Regulations by Chapter 41 “Protection against electric shock”. This chapter highlights four general protective measures that are generally permitted (Regulation 410.3.3):
- Automatic disconnection of supply (Section 411)
- Double or reinforced insulation (Section 412)
- Electrical separation for the supply to one item of current using equipment (Section 413)
- Extra –low voltage SELV and PELV (Section 414)
The application of one or more of these protective measures in an installation needs to take into account the external influence. Section 415 also gives requirements to provide additional protection by the provision of a residual current device (RCD) and supplementary equipotential
bonding for certain conditions, including Special Installations or Locations. For Special Installations or Locations (Part 7) there are particular requirements for each Section that either supplement or modify the requirements of the protective measures defined in Chapter 41.
To view the full article and tables from the IET's Wiring Matters Spring 2009, click on the attachment below...