The 2007 EEA Safety Workshop was held from 11-12 October in Christchurch, and included presentations on temporary earthing and the creation of equipotential zones for work on poles, as well as the publication of the Guide for Work on De-Energized Overhead Lines.

Of particular interest at the Safety Workshop was a presentation made by John Schneider of American Electric Power (AEP). AEP has been carrying out their own testing of the electrical performance of wood poles and the effective means of creating equipotential zones. The pole cluster is extensively used in America, but a need has been identified by some utilities, based on testing, for achieving a better bond to the pole. AEP is testing the performance of a range of solutions for improving equipotential zone establishment on wood poles. There is significant equivalence between the AEP test results and the NZ results. AEP plans further testing and the EEA will continue to liaise with them.

For copies of the Safety Workshop presentations, please contact the EEA office.

The Guide to Work on De-Energised Distribution Overhead Lines has just been published. The Guide contains all guidance being provided by the EEA for work on poles, and replaces the current version of the Guide (Jan 2005), the Notice to Industry (September 2005), and the draft Guide (September 2007). The Guide was issued as a draft in September with a limited consultation period inviting any final comments. Those comments have been evaluated, and final changes to the Guide determined. The changes are described in the Preface to the Guide.

It has been determined by the SSPG that the published version of the Guide will be limited in its application to poles carrying circuits up to and including 33 kV only. Further work is to be carried out to determine recommended solutions for poles carrying circuits above 33 kV. Any solution proposed will be consistent with solutions being adopted by Transpower. The key issue being considered is the reduction in effectiveness of coach screws at these higher voltages, and the need to either replace or to supplement them with downleads which are known to be more effective. This issue has also arisen from a closer consideration of the AEP test information, and discussions held with them.

For a copy of the new guide, please click here.

The SSPG is very appreciative of the comments received on the draft Guide to Work on De-Energised Distribution Overhead Lines, both the March 2007 and September 2007 versions. Commentators provided extensive and detailed comment on the Guide, which were very valuable. All comments were carefully considered and evaluated. While those which can be adopted were, it was not possible to adopt all for a number of reasons. The SSPG trusts that those who made comments that were not adopted will be able to understand why from reading the new version of the Guide.

The following points were raised:

• Several commentators suggested that the style and structure of the Guide could be improved, but time and priorities have not permitted a review of this to be as extensive as some may wish.
• One key feature of difference between the March and September versions was the added inclusion of many more diagrams. The SSPG trusts that users have found this more helpful.
• The SSPG recognises that there are some members of the industry who raised fundamental issues with the Guide, including suggestions that parts of it contain requirements that are unnecessarily onerous. The SSPG has considered these comments, and does recognise the concerns raised. In particular, the SSPG recognises that the implementation of the Guide's requirements may extend job durations and increase costs. During the development of the Guide, consideration was given to the balance between safety and cost, and what 'all practicable steps' means in this context. The SSPG concluded that the appropriate safety practices for temporary earthing had to take priority, with due recognition of the level of risk for the particular work situation.
• It should be noted that there has been a longstanding requirement in the SM-EI Part 3 section 6 to bond any conducting materials on the pole to the conductors being worked on. It was assumed within the industry that wood poles in particular, and to a lesser extent, concrete poles, were sufficiently non conductive not to require bonding. It is now known as a result of investigations (including tests) carried out on both wood and concrete poles following the Arahura fatality, that this assumption is not valid in all cases. Consequently the industry is now aware of a potential hazard which has in the past and could in the future cause serious harm or death under some circumstances. The Guide sets out recommendations on how this hazard can be managed.
• The EEA has had discussions with the Commerce Commission to alert them to expect increases in SAIDI from this safety initiative, and that safety will not be compromised to minimise SAIDI. The SSPG is also aware that if the industry does not take the appropriate safety action there is a risk that the safety Regulator will mandate action.
• Concerns and suggestions were also raised regarding implementation and training. Training materials are being prepared (as explained in 'Training Materials' below). 
• Implementation issues are being discussed by a number of groups and outcomes will be disseminated as appropriate.

The EEA is preparing a set of training materials which can be used to facilitate training presentations to field personnel and others. The materials comprise:

• MS PowerPoint presentation in four parts for presenter's use
• MS PowerPoint presentation handout
• A set of FAQ's
• Feedback form

The material is expected to be made available to industry by April 2008.

Issue 4 of the Temporary Earthing Newsletter covered the factors to be considered in the manufacture of new concrete poles to enable the establishment of an equipotential zone. In addition to those factors and in response to a question from the industry, the SSPG suggests that consideration be given to the fitting of at least two ferrules connected to the reinforcing to enable continuity testing of the ferrule integrity to be undertaken. Testing will become more important as the pole ages.

Work to be completed includes:

• Review section 6 of SM-EI Part 3.
• Determine solutions for poles carrying >33 kV circuits.

The SSPG reinforces the priority which must be given to hazard identification, both at the work planning stage and when at the worksite. Temporary earthing and equipotential bonding is a necessary hazard control, but the focus must be on the means to prevent inadvertent livening from occurring from any source including over or under passing live conductors and adjacent live conductors on the same structures.