the requirements of Section 543 of BS7671:2008, with the effective termination of the earthing conductor at the earth electrode. Additionally, the use of 110V power tools supplied by means of 230/110V portable transformers would have been prudent, and is recognised by BS7671:2008 as the preferred method of protection. Finally, before being put into service, the temporary
installation should have been inspected, tested and certifi ed in accordance with Part 6 of BS7671:2008. Guidance recommends that periodic inspection and testing of construction site supplies is to be carried out at intervals of not greater than three months.
allowed other than at shutdown times, leading to the conclusion that live working had been undertaken under onerous conditions.
The outcome: Fortunately, the inspection was not commissioned as the result of an accident, but clearly the area around the distributions fuseboards presented a hazard, and if adequate safety precautions not been put into position an accident involving electric shock could have ensued.
The installation: This was a small food processing plant where the electrical installation was being upgraded in stages, and work, though temporarily suspended, was in progress. The existing wiring system comprised various systems including singles cable in conduit and trunking and PVC insulated and sheathed cables clipped direct. The initial inspection suggested that there had been several additions to the electrical installation, and that these had perhaps been carried out in stages over a time period of several years. The incoming supply from the distributor was three phase and neutral, with TN-S system earthing.
What went wrong: We became involved at the request of the plant owners, who had become concerned after the comments made by another electrician who attended the site. Their concerns involved the standard of workmanship, compliance with the electrical standards current at the time, and the duration of time being taken to complete the work. We were requested to focus our inspection at the main
distribution position, which was located on a mezzanine fl oor above a cold store. Access to this was by means of a ladder, and the headroom was such that it was necessary to crouch in this area. There were two TP&N distribution boards installed at this location. The doors of these distribution boards were found open, and there was access to live parts within because the barriers were missing. The wiring adjacent to these fuseboards emanated in all directions, and the majority of the cables were either insuffi ciently fastened or totally unsupported. Some cables drooped suffi ciently under their own weight to prevent adequate access to work at the distribution boards. Cable management here was sadly non-existent, and the area – which had no natural light – was not illuminated.
Issues of concern were:
1) Access to live parts-fuseboard doors open with missing internal barriers;
2) Inaccessibility for maintenance to and in the area, and the absence of local lighting; and
3) Unsecured live cables making it diffi cult to work effectively at the fuseboards, unless these were completely isolated – and as this was a food processing plant, it is unlikely that this would be
What should have been done? At every stage of completion of in-progress work when the contractor was leaving the area adjacent to the distribution boards, unattended internal barriers should have been replaced and the doors closed and secured by means of a tool to prevent unauthorised access to live parts. This is basic protection as defined by BS7671:2008.
This could have been avoided by:
Evidence suggested that there was little pre-planning involved with this project, and it was stated by the client that the contractor fi tted the work in around other work (mainly at weekends), and this was the reason for the slow progress of the work. There was no evidence of documentation to demonstrate method statements and risk assessments.
The work should
have been planned to avoid live working, by arranging distribution and circuit changeover from the old to the new wiring at planned shutdown times. In our opinion,
in this case it
would be diffi cult to uphold the
argument for live working
required by The Electricity at Work Regulations 1989 (EAWR) – Regulation 14, i.e., that it is unreasonable in all circumstances to make dead and it is reasonable in all circumstances to work live and, if so, that all adequate safety measures for live working have been taken, including the use of suitable and appropriate safety equipment.
Also, Regulation 15 of EAWR requires adequate
accessibility and lighting for working and maintenance operations. This could be found wanting at the location of the main distribution. We found no evidence of certifi cation, such as
schedules of inspections and test results, even though evidence suggested that some circuits had been added or updated.
More info
ELECSA offers an inspection service providing expert witness reports for clients, including local authorities, trading standards, solicitors, electrical contractors and private clients. It is listed in the UK Register of Expert Witnesses and accepts commissions from clients related to incidents of electrocution, fi res and disputes regarding compliance with British Standards, the diversity of which includes lighting and power, emergency lighting and fi re detection and alarm systems. See
www.elecsa.co.uk or email:
enquiries@elecsa.co.uk
March 2011 ECA Today 65
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