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None of these requirements could be claimed to have been satisfi ed for the installation described.


This could have been avoided by: The installation of a consumer switch-fuse (or linked circuit breaker) at the origin of the submain at the main intake position in the house, designed such that discrimination is achieved between this device and the REC’s main fuse. This would satisfy the requirements of all the regulations listed above, except 411.3.2.3, which could only be satisfi ed if the maximum measured loop impedance is not greater than 0.8 times the maximum tabulated value given in table 41.4 for the type of consumers’ main protective device used. If this cannot be achieved and, because of design constraints it is not acceptable to reduce the protective device rating (or use a different type of protective device) to increase the maximum permitted earth loop impedance, and thus satisfy the maximum permitted earth loop impedance requirements, then an RCD would need to be installed in addition to the switch-fuse. This RCD would need to afford discrimination with any 30mA RCDs affording additional protection downstream, namely those protecting socket outlets. A suitable arrangement for this would be the installation of an upstream 100mA time- delayed RCD.


2) Except for a joint in a cable where Section 526 allows such a joint to be inaccessible, every item of equipment shall be so arranged to facilitate its maintenance and access to each connection. Such facility shall not be signifi cantly impaired by mounting equipment in an enclosure or compartment (Regulation 513.1).


These requirements had not been satisfi ed in the installation of the downlights, as the accessibility to the terminations by electrical design and building construction had been impaired, and these are not exempted from accessibility by Regulation 526.3.


This could have been avoided by: The downlights could have been terminated to the fi xed wiring by unfi xed joint boxes, which could then be pushed into the ceiling void, ensuring care was taken to ensure segregation of the fi xed wiring from the hot surface of the downlight when switched on. The downlights are then able to be ‘dropped’, gaining accessibility to their connections. Alternatively, a ‘maintenance free’ connection type of joint box/enclosure could be used. However, if this is used, it must be recorded on the Electrical Installation Certifi cate as a departure from the regulations, resulting in a degree of safety no less than if compliance with the regulations had been achieved. This is a requirement of Regulation 120.4.


The installation: This was the installation of lighting and power in the kitchen and dining area of a large detached house that had been extended by the building of a single storey extension for the dining room. The wiring system was PVC insulated, and sheathed cables concealed within the building fabric.


What was wrong:


The downlights in the ceiling of the dining area were fi tted into a ceiling that had a tongue-and-groove wood board fi nish. These could be removed, but their connections to the fi xed wiring by the use of joint boxes could not be accessed, as they were fi xed within the ceiling void and there was no access trap into the ceiling void.


The outcome:


In the event of having to gain access to the joint boxes in the ceiling void for maintenance purposes, the ceiling would have to be removed. While this is not a safety issue it is, nevertheless, one of inconvenience.


What should have been done: BS7671:2008 requires: 1) An assessment shall be made as to the frequency and quality of maintenance so that maintenance and repairs can be readily carried out (Regulation 341.1).


May 2011 ECA Today 61


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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


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