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Fully charged Snags & Solutions A practical guide to everyday electrical problems ‘Snags & Solutions’, NICEIC’s problem solving book, is now available in three parts, which cover many commonly-encountered electrical installation problems. All parts take account of the requirements of BS 7671: 2008 (17th Edition of the IEE Wiring Regulations), where appropriate. Part 1 addresses 53 problems relating to earthing and bonding, Part 2 covers 55 problems relating to wiring systems, and Part 3 covers 52 problems relating to inspection and testing. The books are available from NICEIC Direct. To give an indication of the value of these books, a snag and solution is being covered in each issue of Connections. This issue addresses a snag from Part 3 – Inspection and Testing, relating to where steel conduit that does not have an internal circuit protective conductor is found during the periodic inspection and testing of an existing installation.
snags and solutions
snags and solutions A PRACTICAL GUIDE TO EVERYDAY ELECTRICAL PROBLEMS
A PRACTICAL GUIDE TO EVERYDAY ELECTRICAL PROBLEMS
Part 3 Part 2
wiring systems
inspection and testing
2nd Edition
COMPLIES WITH
62
Summer 2011 NICEIC Connections
50_63_technical.2.vb.indd 62
Steel conduit systems Metal conduit systems in older installations are often found to have no internal circuit protective conductor (cpc) installed.
Snag 35 It is a common misconception that where a metal conduit system does not have an internal cpc, the installation is a potential danger. This has been known to result in the incorrect recommendation code to be recorded on a Periodic Inspection Report on the installation concerned, and the installation being judged to be in unsatisfactory condition.
Solution Where no internal cpc is installed in a metal conduit system, the metal conduit system may have been specifically selected by the installation designer to serve as the cpc. Regulations 543.2.2 (indent vi) and 543.2.5 permit metal conduit to serve as a protective conductor for the associated circuit(s). However, Regulation 543.2.5 requires such conduit to satisfy the requirements of indents (i) and (ii) of Regulation 543.2.4, for electrical continuity and cross-sectional area (csa). Furthermore, where a metal conduit system does serve as the cpc, its suitability for continued use for the purpose should be checked by inspection and testing, in accordance with Chapter 62 of BS 7671.
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14/6/11 15:24:52