AS/NZS 4853 was first published in 2000 as a consensus between industries whose assets inadvertently created electrical hazards on metallic pipelines, and the designers and owners of the affected pipelines. Since publication, the standard has been broadly adopted by designers and owners of transmission and distribution pipelines in Australia and New Zealand, and has undoubtedly resulted in safer pipelines.

In response to submissions by the oil and gas pipeline industry, the 2000 revision provided a methodology whereby the risk, in situations where it was either impractical or impossible to achieve the voltage limit nominated in the standard, could be assessed and accepted where appropriate. The methodology was considered appropriate for many buried pipelines that are usually isolated from the public, and when in service are only exposed to human contact for short, planned periods annually, and during construction.

Unfortunately none of the designers, consultants or licensees were comfortable in using the risk assessment approach, apparently because they themselves were not comfortable in accepting the risk from applying risk management.

The 2010 revision of AS/NZS 4853 is prepared on the basis of knowledge gained through 10 years use of the standard, and it represents a substantial change in the approach to the method of calculating voltage criteria based on actual contact scenarios that will place humans in contact with the pipeline. The standard also provides a methodology for assessing the effectiveness of various methods of reducing the risk in situations where the voltage limit cannot reasonably be attained.

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Under the revised standard, the design approach required to identify, analyse and mitigate electrical hazards is clearly defined, and the data necessary to undertake a competent analysis is stated. In situations where the nominated voltage limits cannot be achieved, the risk methodology approach is described.

In developing the draft, the committee has relied to a large extent on the risk management methodology developed by the Energy Networks Association (ENA) for preparation of their document EG-0 Power System Earthing Guide. ENA members are confronted with similar situations to pipelines, where it is impractical or impossible to reduce voltages to ‘harmless’ levels. ENA proposes to make risk assessment software developed by one of their members freely available to users of EG-0 in order to provide an established, traceable and well documented methodology for the risk assessment.

With the current revision of AS/NZS 4853 the ENA EG-0 software is nominated as an approved method of accepting non-compliant voltages on the basis of risk assessment.

Because this document is a joint AS/NZS standard, and because the New Zealand Power System Earthing Guidelines differ from Australian guidelines, AS/NZS 4853 incorporates separate design process sections for use in Australia (Section 5) and New Zealand (Section 6) respectively. The differences relate to compliance requirements only. In final editing, the Committee may choose to combine these requirements.

As an integral component of adopting the risk management approach to assessing electrical hazards, the draft standard has introduced a requirement for development of an electrical hazards management plan for a pipeline, including documenting the design and risk management actions, validating the assessment and periodic review of compliance with the plan, and for testing the effectiveness of mitigation equipment.

This plan is required to be formally approved by the pipeline licensee (oil and gas pipelines complying with AS2885) or the pipeline owner (water and other pipelines). Approval is defined as a conscious decision given in writing by the licensee/owner, and where required by the regulator.

EL-001-23 considers that this requirement is essential to ensuring the integrity of a risk-based methodology, and it will ensure that the licensee/owner accepts responsibility for implementing and maintaining the risk management measures required by the analysis.