Paul Dawson, Commercial Director at electrical accessories and consumables specialist, Niglon, discusses changes to the Earthing requirements in the 18th Edition Wiring Regulations due for publication in July.
Compliance with the 18th Edition of the Wiring Regulations is a mandatory requirement by January 2019. As I write it, our understanding of the changes to the regs is limited to the contents of the draft for public comment (DPC), which has been available to those working in the industry for several months.
While it’s unlikely that much will change from most sections of draft, the electrical sector is still awaiting confirmation that the proposals will be formalised in the finished regs and there is widespread speculation that the Grenfell Tower disaster could prompt some significant revisions to the draft in sections relating to RCD requirements. For now, therefore, let’s set circuit protection to one side on the basis that further changes may ensue, and assume that what we know from the DPC has become an official regulatory framework in the remaining sections.
While they’re often viewed as the rule book for specification and installation best practice, the primary focus of the wiring regs, ever since the first edition back in 1882, has been safety. The regs are there to ensure installers utilise the latest developments in electrical design and technology to protect against fire and electric shocks in any domestic or commercial environment and the 18th edition will build on that 136-year legacy of safe practice with a proposed new section (Part 8) on energy efficiency. Safety will remain their primary function, however, with new stipulations for protecting against electric shock, thermal effects, voltage disturbances, electromagnetic disturbances, selection and erection of wiring systems and earthing arrangements.
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Chapter 54 of the 18th Edition covers earthing arrangements and protective conductors. In the consultation document, regulation 542.1.201 has been modified to require an additional earth electrode, supplementing any earthing facility provided by the electricity supplier to prevent the risk of dangerous touch voltage in the event of the loss of the main connection to earth.
So why is this change needed? And why now? In the early 1970s the utilities sector introduced PME (Protective Multiple Earthing), which provided both a protective and a neutral conductor within the incoming neutral conductor. This system is defined in BS7671 as TN-C-S.
Since then, the PME system has become universally used by energy companies in the UK, providing their residential and business electricity customers with an incoming earthing point. Until now, this has been viewed as a reliable earthing method and its use as a standalone safety measure has been standard practice.
However, concerns about the aging electrical supply network have highlighted the increasing possibility of a loss of the incoming PME supply, which could result in dangerous touch voltage. It’s important to remember that RCDs do not provide protection against open circuit PME faults, so touch voltage hazards could occur without triggering a disconnection of the mains electricity supply to the building. Consequently, the potential risk to life from relying on PME earthing points alone has been reassessed, leading to the proposed changes to earthing requirements in the 18th Edition (BS7671).
Regulation 542.2.2 identifies seven different types of earth electrodes that can be considered to meet the requirements of 542.1.201, one of these is by the use of earthing rods. Although these items have been widely used in the UK electrical market for many years, this will be the first time they have been embedded into the wiring regulations as a requirement for use in conjunction with a PME system.
Niglon’s extensive circuit protection range includes a comprehensive and proven portfolio of earth rods and earthing accessories to help contractors meet the requirements of the 18th Edition’s Chapter 54. Many contractors may already routinely install an earthing rod and understand the need to install it as close as possible to the source of the incoming supply, connecting it to the building’s main distribution board.
The Niglon range includes a choice of four earthing rods to accommodate varying needs depending on the most appropriate earth rod site in relation to the building and incoming supply, and the ground conditions for the location. Each copperbond or galvanised earth rod can be installed with a range of accessories from Niglon, including connector boxes, earth pits, external couplers, driving studs and clamps. The choice of earth rod and accessories will depend on the contractor’s assessment of the individual site’s requirements but the Niglon range ensures that all their requirements can be met with robust, durable cost-effective and simple-to-install products from a single-source supplier, ensuring compatibility on site.
For more information please visit: http://www.niglon.co.uk/
