FEATURE ELECTRICAL DESIGN SOFTWARE
RETROSPECTIVE DESIGN helps to maintain compliance
Checking compliance can be greatly facilitated by using the right retrospective software design tools, says Tony Schumacher of Amtech
I
t is not uncommon for electrical installations to be altered over time as
building usage changes. When this happens, it is important that electrical engineers working on these installations ensure the installation is compliant with the latest standards. Using the right electrical design software to model the existing installation can save a great deal of time in identifying areas of non- conformity and restoring the installation to a compliant condition. There are a number of reasons why this
is important, not least the necessity to ensure safety of people. Non-compliance with BS 7671 may form the basis of prosecution by the Health & Safety Executive. In addition, a non-compliant installation may lead to equipment failure and expensive downtime. Reduced voltages leading to lower lighting levels, damage to voltage-dependent IT equipment and motors failing to start are all possible outcomes. Moreover, a non- compliant installation may invalidate insurance cover, leaving the building owner financially responsible in the event of an incident. Loss of insurance cover due to non-compliance has been known to put companies out of business. One of the problems facing electrical
engineers is that changes made to electrical installations are often not documented as they should be and so records become out of date. A common example of this is that, whilst condition reports may confirm disconnection times are within the requirements of BS 7671, they do not determine that the installation’s voltage drop requirements have been maintained. This can cause significant problems. For
example, when an installation is enlarged, the voltage within it drops and so the conductor running temperatures increase. Circuits at the remote end of such an installation will cause voltage to be reduced at the upstream distribution boards, thereby impacting the voltage at other terminals. In this way increased loading in one section may adversely affect conditions in another. One of the requirements of the 17th
24 APRIL 2016 | ELECTRICAL ENGINEERING
Edition Wiring Regulations is to verify that voltage drops satisfy the requirements of BS 7671, and identify any departures from the original design. Traditional methods for confirming that the voltage drops are compliant are both complex and time consuming and it can be difficult to confirm the validity of the results.
RETROSPECTIVE DESIGN An alternative is to retrospectively design these older installations using appropriate software so that any issues are quickly identified and can be rectified. This approach is carried out in six stages. Firstly, survey the existing installation then, secondly, ‘build’ it in the design software using
identifying areas that, although compliant today, may not be compliant in the future if further alterations are made to the installation (stage six).
RESPONSIBILITIES When dealing with electrical installations it is clearly important to be aware of who is responsible for what. When a larger installation has been
the data from the survey to create single line and schematic designs. Thirdly, use the software to verify the installation, making use of the built-in voltage drop calculations. Appropriate software will automatically default to the voltage drop limits stated in Appendix 4, Section 6.4 of the regulations. Alternatively, user-derived voltage drop limits can be applied. Following completion of these first three stages, the fourth stage is to view non- compliant areas within the software. This enables use of the software to redesign the installation (stage five) and make any required modifications to achieve compliance. The software should also incorporate the ability to model ‘what-if’ scenarios,
completed, the Electrical Installation Certificate will usually require signatures, each representing the responsibilities of that signatory. These responsibilities encompass the design of the installation, the installation of the component parts and the verification of the installation. Once compliance with BS 761 has been verified the client takes responsibility for the upkeep of the installation through a ‘duty of care’ under the Electricity At Work (EAW) Regulations. The EAW Regulations also place duties on employers, employees and self-employed personnel to design, install, operate and maintain electrical equipment. This means that anyone responsible for
modifying an existing electrical installation must be aware of the possible implications of any such alterations. In addition to evaluating the impact of any previous changes, it therefore makes sense to use appropriate electrical design software to verify any planned future additions to the installation so that non- compliance can be avoided.
Amtech
www.amtech.co.uk T: 0800 028 28 28
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