Implications for designers using EG(0), The Power System Earthing Guide

Richard RobinsonDue Diligence

The change from hazard based risk assessment supported by the risk management standard to the precautionary due diligence approach now mandated by most Australian parliaments has significant implications for designers, especially in the use of standards that use target levels of risk and safety such as EG(0) Power System Earthing Guide and IEC 61508 the Functional Safety Assessment standard as a design tool.

In previous blogs we have explored the implications of the hazard based approach using target risk criteria for land use safety planning purposes for hazardous chemical facilities. This blog looks at the implications in relation to the application of EG(0), the Power System Earthing Guide1. The guide appears to define risk limit targets consistent with the NSW Department of Planning guidelines as shown in the table and figure below.

EG-0 individual risk limits

EG-0 societal risk limits

  • Intolerable Region—The risk profile must be reduced.
  • ALARA Region—Reduce the risk profile whenever possible, and only accept the residual risk on the basis of a risk cost benefit analysis (RCBA) (see Appendix F). The use of the ALARA principle (or ALARP) is clearly intended to form a key part of the Due Diligence process embodied in this Guide. The ALARM principle that requires a designer and asset owner to reduce the risk profile whenever possible provides a consistent yet practical means for managing earthing system related risk.
  • Low or tolerable Region—Risk generally acceptable, however, risk treatment may be applied if the cost is low and/or a normally expected practice.

Whilst the table has further caveats that consider some of the weaknesses of the hazard based approach to risk, the overall use of such target risk levels remains contrary to the SFAIRP approach of the model legislation.

Such an approach is especially problematic in states like Queensland that are modifying the provisions of the Electrical Safety Act to be entirely consistent with the provisions of the WHS act including penalties.

As a consequence, the attempt by Energy Networks Australia (ENA) to introduce target risk based processes to assess the safety of earthing systems via EG(0), is flawed. It means that organisations and their officers that use such target risk based processes as the primary tool for risk decision making would be subject to post event scrutiny under the new model WHS legislation. In the event of a fatality such officers would presumably be prosecuted for acting recklessly under the criminal provisions of the act. It may also leave the ENA and its officers open to prosecution for endorsing and promoting an arguably suspect process.

This blog is based on a paper presented at the Earthing, Lightning & Surge Protection Conference in July 2013 and subsequently the Electrical Regulatory Compliance Forum in September 2013. The full papers can be viewed at Conferences

1 Energy Networks Association Limited (2010). EG-0 Power System Earthing Guide. Part 1: Management Principles. Version 1 – May 2010. Canberra.