Earth Test Mandatory Requirements

1  SUMMARY

  • The requirement for testing and maintaining any High Voltage installation Earth System is a mandatory obligation in Western Australia.
  • Each of the applicable standards contains a mandatory requirement for “Periodic tests” of earth systems.
  • There is no defined period between tests for any specific site aside from the advisory note that a maximum of two years between tests is considered reasonable.
  • The obligation to keep records identifying the base line installed earth resistance for each High Voltage installation and then dates when subsequent tests were conducted for each site tested on a basis that could reasonably be seen as maintaining that earth system safety.
  • Where there is doubt as to the adequacy of the installation as established by earth resistance testing, an injection test is advised.
  • The results and dates of tests along with any condition related information is required to be included in the Electrical Record Book.

o There are substantial penalties associated with a failure to comply with these regulations.

  • These requirements are covered by a number of regulations and standards.  The primary Authority for the obligations is derived from the Electricity Act of 1945, under the Regulations of 1947, as amended from time to time.  The mandatory requirements are clearly identified in the Western Australian Electrical Regulations [WAER], which requirements apply to electrical installations in WA.

2.0  TEST REQUIREMENTS
The obligation for earth system tests are identified within the WAER, AS/NZS 3000, and
AS NZS 2067.  Between them, these documents refer to other standards and advisory
publications which contain compliance and advisory comments to support the
obligations.  These being: EG-(1) and the WA Mines Safety and Inspection regulations
and AS NZS 1768.

2.1   The WAER 2014 [Western Australian Electrical Regulations 2014]
The WAER is issued by the Government of Western Australia Department of Commerce
Energy Safety. The document contains mandatory obligations as follows
Electrical  installation  designs  commenced  after  1  July  2014  must  comply  with  this
January 2014 version.
Designs started before 1 July 2014, and projects under construction or for which building
contracts  are  signed  at  that  date,  may  comply  with  the  earlier  July  2008  version.  The
application of amendments to the WAER is not retrospective.
Compliance  with  the  WAER  is  mandatory  under  Regulation  49  of  the  Western
Australian Electricity (Licensing) Regulations 1991.  
The  WAER  should  be  read  with  the  Electricity  Regulations  1947,  Part  VIII,  and  the
Electricity (Licensing) Regulations 1991. Both sets of regulations take precedence. The
document makes frequent references to relevant Australian Standards. As a general rule,
nothing in those standards is replicated in the WAER.
Further specific requirements may be found in:
o  Energy Networks Association EG-(1) Substation Earthing Guide

  • Earthing systems shall comply with the relevant technical standards, including:

o  the Wiring Rules;
o  AS/NZS  2067:2008  –  Substations  and  high  voltage  installations  exceeding
1kV a.c.; and
o  The WA Mines Safety and Inspection Regulations 1995. “The maintenance
system must include; rr. 5.27.(2) (c) routine testing of the effectiveness of the
earthing  system, the continuity of earthing conductors and the adequacy of
electrical insulation”

  • The earthing system in all electrical installations shall be the Multiple Earthed

Neutral (MEN) system as defined by the Wiring Rules, unless otherwise permitted
for mining operations

  •  Failure to comply with a requirement may result in prosecution under the Electricity

(Licensing) Regulations 1991.

2.2  AS NZS 3000 Wiring Rules
Compliance with the Electricity Act determines that all electrical works in Australia are
undertaken in accordance with these Wiring Rules being AS/NZS 3000:2007 – published by
the Australian Standards Association.  The Standard sets out requirements for the design,
construction and verification of electrical installations Essentially the Standard is made up of two parts

  • Part 1 provides uniform essential elements that constitute the minimum regulatory requirements for a safe electrical installation.
  • Part 2 provides installation practices that achieve certainty of compliance with the essential safety requirements of Part 1

 a)  Earth system requirements are specifically addressed in section 5,
b)  High Voltage requirements are identified in Section 7,
c)  Earth System testing and inspection requirements are identified in section 8 of the
standard

2.3  High Voltage Installations – AS/NZS 2067
AS/NZS 2067:2008 is the Australian standard which identifies the minimum compliance
requirements for High Voltage Installations. This Standard provides minimum
requirements for the design and erection of high voltage installations in systems with
nominal voltages above 1 kV a.c.  Under this standard, the Earthing System is
determined as forming part of the High Voltage System.
Clause 8 of the standard provides the criteria for design, installation, testing and
maintenance of an earthing system. The commissioning inspection and testing program is
to prove adequate quality, as well as voltage limits, and provide the supervision process
with benchmark or baseline figure.
The standard requires that once the earthing system commissioning program is complete,
the risk profile of the system shall be verified as a final step prior to the handover
process. [Verification as per AS NZS 3000 section 8] Both the physical aspects of the installation and safety performance are to be reviewed, and any irregularities investigated
using the detailed design process to determine if any remedial actions which maybe
required.
The documentation associated should include details such as:

  • Physical location of the system being tested,
  • Details of the installation and tests conducted,
  • The electrical assumptions made by the design engineer such as load and fault
  • level,
  • Design decisions relating to earth mat, electrodes and connection,
  • Commissioning data identifying which tests were conducted and the results,
  • Supervision of the installation relating to unseen items connections and materials,
  • and,
  • Maintenance requirements as proposed by the design engineer based on his
  • design assumptions.

 3.0  SITE TESTS
Each High Voltage Substation will need to be inspected and tested to establish base line data
to allow compliance with regulatory requirements.  The recommended tests include:

  • Electrical Connection integrity tests,
  • Earth Stake resistance tests,
  • AC Current injection tests to measure EPR

a)  The electrical connection tests are conducted with a quality multimeter or a ductor, to
ensure there is no high resistance connection or earth circuit; Results demonstrate
compliance with AS NZS3000 Section 5,7 and 8
b)  Earth Stake resistance tests establish a base line.  If a subsequent injection test
demonstrates an EPR compliant installation, then future routine tests of earth stake
resistance will be the only test required to confirm installation integrity.
c)  AC Current injection tests, will confirm a safe level of EPR under fault conditions.  If a
safe level is not demonstrated, the electrode resistance tests above can be used to identify
how the installation can be remedied to ensure compliance.

T.P MULLIGAN
MIEEE WA EW 102511 EC 10290
Member EL 024 Committee – Australian Standards

15 th  June 2016