Code of Practice Electricity transmission and distribution asset management. February 2009

Transcription

1 Code of Practice Electricity transmission and distribution asset management February 2009

2 CONTENTS 1 PREFACE APPLICATION AND OBJECTIVES SCOPE DEFINITIONS DESIGN AND CONSTRUCTION Application General Materials Environmental Considerations Thermal Ratings Short Circuit Ratings Mechanical Loading Conditions Electrical Service Conditions and Physical Environment Prevention of Unauthorised Access Installation Water Crossings Records Overhead Lines General Conductor Tensions Structures and Footings Facade Mounted Cables Safety Clearances Overhead Service Lines Underground Cables General Installation Parts of an Underground Cable Installed Above Ground Underground Service Lines Substations General Substation Electricity Works Clearances to Exposed Live Electricity Works Structural Design of Buildings and Roofed Enclosures Kiosk Type Substations Ground Type Substations Pole Mounted Substations Earthing and Electrical Protection General Step and Touch Potentials...19 NSW Department of Water and Energy, February 2009 Page 1 of 45

3 6 MAINTENANCE General Maintenance of Overhead Lines Maintenance of Underground Cables Maintenance of Substations Maintenance of Protection and Earthing Systems Environmental Considerations SAFE ELECTRICAL WORK PRACTICES General Qualifications and Training General Requirements Employer Responsibility Employees in Training General Safety Provisions Basic Safety Principles Hazard Identification and Risk Assessment Hazard Control Minimum Safe Working Distances Correct Labelling and Recording of Electricity Works Hazardous Electrical Occurrences or Effects Precautions for Energisation and Re-energisation of Electricity Works First-aid Protective Clothing Work in Confined Spaces Operating Work Access Permits Work on Low Voltage Electricity Works De-energised LV Electricity Works Live LV Electricity Works Work on High Voltage Electricity Works De-energised HV Electricity Works Live HV Electricity Works Work on Overhead Lines Work on Underground Cables Cable identification Precautions for Work on or Near Cables Access into Substations Work in Substations Tools and Safety Equipment...30 NSW Department of Water and Energy, February 2009 Page 2 of 45

4 Appendix: Acts, Regulations, Australian Standards, Codes and Guides relating to the Design, Construction, Maintenance and Safe Electrical Operation and Work Practices for Transmission & Distribution Systems...31 SECTION A: STANDARDS, CODES AND GUIDES RELATING TO OVERHEAD LINES AND SERVICES...31 SECTION B: STANDARDS, CODES AND GUIDES RELATING TO CABLES AND SERVICES...35 SECTION C: STANDARDS, CODES AND GUIDES RELATING TO SUBSTATIONS...36 SECTION D: STANDARDS, CODES AND GUIDES RELATING TO PROTECTION AND EARTHING SYSTEMS...40 SECTION E: STANDARDS, CODES AND GUIDES RELATING TO SAFE ELECTRICAL OPERATION AND WORK PRACTICES...42 SECTION F: RELEVANT ACTS AND REGULATIONS...43 NSW Department of Water and Energy, February 2009 Page 3 of 45

5 1 PREFACE This Code has been made available by the Department of Water and Energy without significant amendment of the Code prepared for the Electricity Association of NSW by a working group with representatives from the following organisations: Energy Australia Integral Energy NorthPower Great Southern Energy Railway Services Authority BHP TransGrid Advance Energy The Code was circulated to the following groups prior to finalisation: Consumer groups Public/regional interests Occupational health and safety agencies Insurance interests Electrical contractors Distribution equipment suppliers and Service Providers Network Operators This Code has been recognised by the Director-General of the Department of Water and Energy for the purposes of network operator s licences. The use and impact of this Code will be monitored through the Industry Safety Steering Committee (ISSC) who may seek to revise the Code as may be appropriate from time to time. Comments are welcome and can be sent to the Department as follows: Manager, Energy Networks Performance Policy Department of Water and Energy Level 17 Elizabeth Street SYDNEY 2000 Note: This Code is one of a number which will apply to the design, construction and/or maintenance of electricity works or installations. Other Codes of Practice which may be applicable include: - Contestable Works - Installation Safety Management - Service and Installation Rules - Distribution Risk Management NSW Department of Water and Energy, February 2009 Page 4 of 45

6 2 APPLICATION AND OBJECTIVES The Electricity Supply Act 1995 (The Act) provides the framework for promoting industry efficiency generally through establishing a balance of competition and regulation. There is also scope for benefit to customers as a whole in limited standardisation of infrastructure design and service procedures which promote: community safety, compatibility among electricity supply systems, economies of scale, and freedom for buyers to exercise choice. This Code of Practice is intended to promote common practices in electricity transmission and distribution to embed in the State s electricity supply infrastructure, its operation and maintenance, features which are generally accepted as appropriate for meeting the needs of the public in terms of safety, access and network impacts. This Code of Practice aims to provide guidance as to cost effective practices and procedures which are intended to protect the interest of customers and the public. The Code is intended to be adopted by licence holders under The Act. There may be local reasons for departing from or not adopting this Code in its entirety. A licence holder is required to state its policy on the adoption of this Code in its licence compliance annual report. The availability of this Code will also support the streamlining of the regulatory regime under The Act by providing guidance on achieving the minimum standard of electrical safety to customers, the public and industry workers, contractors and their employees. This Code shall be followed unless there is an alternative course of action which achieves the same or better outcomes. Being a guide, this Code does not in general stipulate prescriptive details on the design, construction, operation and maintenance of all electrical assets, nor provide all relevant information. Individual organisations shall produce their own detailed manuals and work procedures where necessary, with due regard to all relevant standards which are appended in this Code. NSW Department of Water and Energy, February 2009 Page 5 of 45

7 3 SCOPE This Code outlines the policy and standards which apply to the design, construction, maintenance and operation of electricity works. The Code will apply to Network Operators, Service Providers and any of their subcontractors working on electricity works or operating electricity transmission or distribution systems. The design, construction and maintenance provisions of the Code apply to all electricity transmission and distribution systems whether or not the system is: out of service, or being constructed and has never been energised. The safe electrical operation and work practices provisions apply to work on, and operation of, the electricity transmission and distribution system except where: the system cannot be energised by operating work because of the absence of electrical connections to any possible source of electricity supply, or no person and no material or equipment not insulated for the voltage concerned, can come near to any exposed conductor which is live or can be energised by operating work. This Code does not apply to railway traction overhead wiring which is regulated by the Rail Safety Act NSW Department of Water and Energy, February 2009 Page 6 of 45

8 4 DEFINITIONS The Act means the Electricity Supply Act Access permit means a pre-printed form which, when issued in accordance with a documented procedure adopted by the Network Operator, gives permission to the recipient to work on or near to, or test, electricity works. Approved means having appropriate organisation endorsement in writing for a specific function. AS means an Australian Standard, as published and amended by Standards Australia on the date this Code comes into operation. Authorised means has the permission of the appropriate authority in writing for the duty concerned. Bare in relation to a conductor means not insulated. Cable means an insulated conductor or two or more such conductors laid together, whether with or without fillings, reinforcements or protective coverings. Carriageway means that portion of a public road which is improved or designed for use by, or used by, vehicular traffic, including any road shoulder and breakdown lane but not including any footpath or other lateral part of the road not so improved, designed or used, or that portion of a defined vehicular track (whether formed or unformed) which is ordinarily used by the public and which is located on a road reserve or on land under the control of the Western Lands Commissioner or in a national park, State forest or Crown land, and includes the entire width of the defined vehicular track plus 2.5 metres on each side of the track. Confined space means confined space as defined in The Occupational Health and Safety (Confined Space) Regulation, 1990 (as amended). Conductor means a wire, cable or form of metal designed for carrying electric current. Covered Conductor means a conductor around which is applied a specified thickness of insulating material. There are generally two types of covered conductor: Covered Conductor (CC) where the nominal covering thickness is independent of working voltage; and Covered Conductor Thick (CCT) where the nominal covering thickness is dependent on the working voltage. NSW Department of Water and Energy, February 2009 Page 7 of 45

9 De-energised means not connected to a source of electrical supply. Earthed means electrically connected to the general mass of earth. Electricity works means any electricity power lines or associated equipment or electricity structures that form part of a transmission or distribution system. Employee means a worker in the employment of an employer (whether under a contract of employment or apprenticeship) and includes a contractor or sub-contractor, and a person employed by a contractor or sub-contractor, who carries out work for an employer. Employer means a Network Operator or Service Provider, as the case may be. Exposed conductor means an electrical conductor, approach to which is not prevented by a barrier of rigid material or by insulation which is adequate under a relevant Australian Standard specification for the voltage concerned. Extra low voltage means voltage normally not exceeding 32 volts alternating current or 115 volts direct current. Fire rating means the minimum period of time during which an element of a structure may be expected to function satisfactorily while subjected to the Standard Fire Test provided for in the Australian Building Code. Ground type substation means a semi-enclosed, free standing substation which is connected to a high voltage aerial line or underground cable. High voltage or HV means a voltage normally exceeding 1,000 volts alternating or exceeding 1,500 volts direct current. Insulated means separated from adjoining conducting material by a non-conducting substance which provides resistance to the passage of current, or to disruptive discharges through or over the surface of the substance at the operating voltage, and to obviate danger of shock or injurious leakage of current. Insulated conductor means a conductor which is wholly covered with insulating material in accordance with the relevant AS or equivalent. Isolated means disconnected from all possible sources of electrical energy by the opening of switches, withdrawal of circuit breakers, removal of fuses, links, connections and the like and rendered incapable of being made live unintentionally. Kiosk type substation means a totally enclosed, free-standing, self-contained substation not designed for bodily entry and which is generally operated from door openings. Live means connected to a source of electrical supply or subject to hazardous induced or capacitive voltages. Low voltage or LV means voltage exceeding 32 V a.c. / 115 V d.c. but not exceeding 1000 V a.c. / 1500 V d.c. NSW Department of Water and Energy, February 2009 Page 8 of 45

10 Maximum design temperature means the maximum temperature which the conductors may reach under the influence of load current (excluding fault current), ambient temperature of the air and solar radiation. Near means a situation where there is a reasonable possibility of a person, either directly or through any conducting medium, coming within the relevant safe working distances specified in this Code. Network Operator means a Network Operator as defined by The Act. Neutral conductor means a conductor of a Low Voltage system which is earthed at its origin. Nominal voltage (U) means the AC (phase to phase RMS) or DC voltage by which a system of supply is designated. Operating Work means work involving the operation of switches, the opening or closing of links or other connections intended for ready removal, the removal or replacement of fuses, proving that electricity works is de-energised and the earthing and short-circuiting of electricity works. Overhead line means any aerial conductor or conductors with associated supports, insulators and other apparatus erected, or in the course of erection, for the purpose of the transmission, distribution or conveyance of electrical energy. Other cable systems means, telecommunications and control cables, aerial earthed cables or electrolysis drainage cables attached to or crossing a Network Operator s overhead line or otherwise in the proximity of the overhead line. Pole mounted substation means a substation mounted on one or more poles. Premises means any house, building or structure including the land associated with it. Protective equipment means equipment which is intended to isolate the active conductors of a circuit if an electrical fault occurs. The Regulation means the Electricity Supply (Safety and Network Management) Regulation Road means any thoroughfare ordinarily used by vehicular traffic. Safe means not posing a risk to life, health or property. Screened cable means that the insulation covering the conductor cores is covered by a conducting or semi conducting material which is connected to a neutral or earth. NSW Department of Water and Energy, February 2009 Page 9 of 45

11 Service line means the part of an electricity distribution system that forms the terminating span of an electric line which: is constructed or designed or ordinarily used for the supply of electricity at low voltage, and is intended to supply electrical energy to a customer either from a main or directly from the premises or structure of the Network Operator. Service Provider means a Service Provider as defined in the Code of Practice - Contestable Works. Substation or Electrical station means any premises or place in which high voltage supply is converted, controlled or transformed. Supply means supply of electricity. Underground cable means a cable which is placed under the ground and may include portions which are erected above the ground. Voltage means a potential difference between conductors and between conductors and earth. NSW Department of Water and Energy, February 2009 Page 10 of 45

12 5 DESIGN AND CONSTRUCTION 5.1 Application This section of the Code applies to all electricity works placed into service on or after the recognition of this Code by the Department of Water and Energy and to any part of an electricity works which is upgraded, renewed or replaced after that commencement. Electricity works in service prior to the commencement of this Code are covered by the regulation or law in force at time of their construction. 5.2 General All electricity works shall be designed to be safe for the electrical conditions likely to be experienced during service and the physical environment in which they will operate, taking into account acceptable risk management techniques. [Note: When purchasing new equipment, it is considered prudent to take into account Australia s possible response to international trends to change the supply voltages of 220V and 240V to 230V.] The documents referred to in the appendices to this Code should be considered for the design and construction of electricity works. Where there are variations between the documents referred to in Appendices A, B, C, D and E, and this Code, the Code is to take precedence Materials All materials used for electricity works, their components, conductors, accessories and support structures shall ensure safe operational performance Environmental Considerations The design, construction and installation of electricity works shall take into consideration environmental issues and concerns. Factors to consider include, but are not limited to: the promotion of energy efficiency, the efficient use of non-renewable resources, the use of renewable resources, the social impact of new projects, and community concerns, the minimisation of environmental damage, including visual impacts, tree management programmes, a reduction in and the correct disposal of waste products, and the consideration of Electromagnetic Field (EMF) issues. NSW Department of Water and Energy, February 2009 Page 11 of 45

13 5.2.3 Thermal Ratings The thermal capacity of electricity works shall be sufficient to pass the electrical load for which they are designed, without reduction of mechanical properties to a level below that which provides safe operational performance Short Circuit Ratings The electricity works shall be of sufficient capacity to pass short circuit currents which will enable the correct operation of protective devices so that a fault is cleared without reduction of mechanical properties to a level below that which provides safe operational performance Mechanical Loading Conditions The electricity works shall have sufficient mechanical strength to withstand anticipated mechanical stresses due to environmental and electrical service conditions Electrical Service Conditions and Physical Environment In determining the electrical service conditions and the physical environment under which the electricity works will operate, due and reasonable care shall be given to the consideration of extremes that may occur, the likelihood of their occurrence and the associated risk Prevention of Unauthorised Access All electricity works with exposed live parts shall be so designed and constructed that unauthorised access to any person is prevented as far as is reasonably practicable Installation Electricity works shall be installed in accordance with relevant standards Water Crossings Water crossings (overhead and underground) shall be designed, constructed, installed and maintained in a manner that complies with the requirements of the appropriate authorities, including the installation and maintenance of appropriate signage Records All design, construction, operation and maintenance records that are relevant to safety shall be kept in an accessible form. NSW Department of Water and Energy, February 2009 Page 12 of 45

14 5.3 Overhead Lines General Overhead lines shall be designed and constructed to: have insulation appropriate for the nominal voltage, carry the electrical load currents for which they are designed, allow the passage of electrical short circuit currents which will enable the correct operation of protective devices, ensure they are structurally secure for the environmental and service conditions for which they are designed, maintain safe clearances, ensure that safe operational performance will occur, and prevent unauthorised access to the electricity works. This includes overhead service lines, insulated and covered cable systems Conductor Tensions The conductors for use with overhead lines shall be designed to withstand the mechanical loads over the designed operational life, without failure Structures and Footings The structures and footings for use with overhead lines shall be designed to withstand the mechanical loads over the designed operational life, without failure. Due consideration shall be given to the environmental conditions likely to be experienced during service Facade Mounted Cables Cables and accessories used for facade mounting shall be constructed with suitably insulated conductors and be manufactured to be durable for the environmental service conditions likely to be experienced Safety Clearances Overhead lines and other cable systems shall be designed to maintain safety clearances to the ground and buildings or structures under the environmental and electrical service conditions determined for the line. NSW Department of Water and Energy, February 2009 Page 13 of 45

15 TABLE Clearances to Ground of Exposed and Insulated Conductors Overhead lines, excluding service lines, other cable systems and aerial lines within substations, shall have all conductors located so that the distances to ground in any direction from any position to which any part of such conductors either sag at maximum design temperature or move as a result of wind pressure which could reasonably be expected to occur at the location of the overhead line, are not less than the distances specified in Table 1. Nominal system voltage (U) (Volts) Exposed or insulated U < OR Insulated conductor with earthed screen U > Insulated conductor without an earthed screen U > Exposed or covered conductor < U < < U < < U < < U < < U < Over the carriageway of roads (mm) Over land other than the carriageway of roads (mm) Over land which due to its condition is not traversable by vehicles (mm) Clearances to Ground of Insulated Service Lines TABLE 2 Aerial service lines and other cable system shall have the line located so that the distances to ground in any direction from any position to which any part of such lines either sag at maximum design temperature or move as a result of wind pressure which could normally prevail, are not less than the distances specified in Table 2. Service line and other cable systems location Distance from ground any direction (mm) Over the centre of each carriageway of a public road Over any part of a Freeway, Primary Arterial Rd or Highway Over any part of a carriageway of a public road (other than the centre) Over a vehicular crossing of a footway in a public road (other than a residential driveway) Over land which is not associated with a residential dwelling which is likely to be used by vehicles Over a vehicular crossing of a footway in a public road for a residential driveway and any other part of a footway Over land which is, or likely to be, used by vehicles and is associated with a residential dwelling Land not likely to be used by vehicles NSW Department of Water and Energy, February 2009 Page 14 of 45

16 Clearances from Structures The minimum clearance from any structure or line support (other than the structure supporting the line) to any position an overhead conductor may swing or sag shall be such as to prevent injury to persons or damage to property. The minimum clearances shall be obtained by reference to ENA C(b)1 as amended. For service lines reference shall be made to the Code of Practice for Service and Installation Rules Clearances to Conductors of Other Circuits The arrangement of and clearances between circuits, either attached to a common structure, unattached, in shared spans or crossing, must be designed for the environmental and electrical service conditions likely to be experienced in service. Clearances to railway traction overhead wiring shall be in accordance with the requirements of the railway owner Alterations to Ground Levels Where any land above which overhead lines have been erected undergoes a change of use that varies the ground clearances, the portions of those overhead lines which are situated over the land shall be reconstructed to satisfy clauses 5.3.5, , , and above Overhead Service Lines Overhead service lines shall comply with the Code of Practice for Service and Installation Rules. NSW Department of Water and Energy, February 2009 Page 15 of 45

17 5.4 Underground Cables General Underground cables shall be designed and constructed to ensure that: they have insulation appropriate for the nominal voltage, they will carry load currents for which they are designed, they (and their cable screens or sheaths when applicable) will pass short circuit currents which will enable the correct operation of protective devices, safe separation clearances from other services are maintained, and safe operational performance will occur Installation Cables shall be installed in a manner that takes into account the local environmental and service conditions, taking into account the location of other utilities services. Suitable precautions shall be taken during installation and jointing that safeguard against: the possibility of transferred earth potentials when installing cables, the possibility of induced voltages when installing long lengths of cable close to in-service cables, the possibility of mechanical damage to existing cables or joints when excavating or installing cable, and damage to the environment Parts of an Underground Cable Installed Above Ground Where an underground cable is located above the surface of the ground it shall be mechanically protected to a height of 2400mm from any surface on which a person can stand to the point where it enters the ground Underground Service Lines Underground service lines shall comply with the Code of Practice - Service and Installation Rules. NSW Department of Water and Energy, February 2009 Page 16 of 45

18 5.5 Substations General Substations shall be designed and constructed to ensure: Compliance with the relevant building codes, where applicable. Safe access and egress. The buildings and enclosures are to be structurally secure, taking into account the local environmental and service conditions. The buildings and enclosures are to be secured in a manner that ensures all reasonable care is taken to prevent entry by unauthorised persons. The electricity works shall have insulation appropriate for the nominal voltage. The electricity works shall carry electrical load currents for which they are designed. The electricity works shall carry short circuit currents which will enable the correct operation of protective devices. Safe clearances to electricity works are maintained. Safe operational performance Substation Electricity Works Substation plant and equipment including busbars, cables, circuit breakers and ancillary equipment, transformers, capacitors and surge diverters shall meet standards which will ensure safe operational performance Clearances to Exposed Live Electricity Works Substations shall be designed to provide safe operating and working clearances from exposed live equipment and lines Structural Design of Buildings and Roofed Enclosures The requirements of the Building Code of Australia apply. In addition consideration should be given to: the provision for plant and equipment that may be installed, the provision for ventilation requirements for plant and equipment that may be installed, the control of ground waters in sub-surface buildings, the containment of insulating liquids, the provision of fire protection, the control of the products of explosion that may occur, and the provision for impulse loading and forces due to short circuit conditions. NSW Department of Water and Energy, February 2009 Page 17 of 45

19 5.5.5 Kiosk Type Substations Kiosk type substations shall be installed in accordance with the Building Code of Australia. The enclosure of a kiosk type substation shall be robust and sturdy Ground Type Substations The structures supporting aerial lines in ground type substations shall allow for mechanical loading and for forces under short circuit conditions Walls and Fences Walls and fences enclosing the substation shall: be so arranged to prevent unauthorised entry, display appropriate warning signs, be suitably earthed where appropriate, comply with the Building Code of Australia, and provide safe horizontal and vertical clearances to any live and exposed equipment [AS is a guide in this regard] Pole Mounted Substations Pole mounted substations shall comply with the following: Structures supporting aerial lines on pole type substations shall allow for mechanical loading and forces under short circuit conditions. All parts of supporting platforms and equipment which are mounted on or attached to the pole or crossarms, except for conductors, are at a height not less than in Table 3 below: TABLE 3 Location More than 500 mm from the vertical projection of the kerb line in the direction away from the vehicular carriageway Height above ground (mm) Elsewhere Any electricity works mounted below 3600mm shall not protrude more than 200 mm from the pole and maintain a minimum of 500 mm from the vertical projection of the kerb line, and not facilitate unauthorised climbing of the pole. NSW Department of Water and Energy, February 2009 Page 18 of 45

20 5.6 Earthing and Electrical Protection Earthing and electrical protection systems shall be designed and installed to safely manage abnormal network conditions likely to be experienced, without significant risk of injury to people or damage to property General Earthing and protection systems shall be designed and installed to ensure: the reliable passage of fault current, the reliable passage of Single Wire Earth Return (SWER) load currents to ground and/or source, the reliable operation of circuit protection devices, that step, touch and transfer potentials are limited to safe levels, appropriate co-ordination with other utilities systems, suitability for the environmental and earthing conditions, protection against likely mechanical damage, inadvertent interference and chemical deterioration, and mechanical stability and integrity of connections Step and Touch Potentials All exposed conductive material (excluding the current carrying conductors) which is accessible to persons and which could be energised in the event of a primary insulation failure of the circuit, shall be effectively earthed to avoid injury from electric shock. NSW Department of Water and Energy, February 2009 Page 19 of 45

21 6 MAINTENANCE 6.1 General All electricity works shall be maintained to ensure safety to persons and reliability of supply, taking into account the associated risks. The relevant documents referred to in the appendices to this Code should be considered for the maintenance of electricity works. Where there are variations between the documents referred to in Appendices A, B, C, D and E, and this Code, the Code is to take precedence. A system of maintenance shall consist of the following elements: a list of network assets and their respective locations, a schedule of maintenance activities based on an assessment of risk, and a record of maintenance work carried out. 6.2 Maintenance of Overhead Lines Overhead lines, their structures and their components shall be maintained to be in a safe operating condition. The integrity of insulation of overhead lines shall be maintained. A system of maintenance for overhead lines, their structures and components shall consider: inspection and/or testing programmes, maintenance programmes, replacement programmes for components approaching the end of their serviceable life, and tree management programmes designed to: ensure public safety, minimise the risk of fires caused by contact between trees and overhead lines, reduce the number of interruptions to supply caused by trees, and protect the electricity distributor s assets from damage. 6.3 Maintenance of Underground Cables Underground cable systems shall be maintained in a safe operating condition. A system of maintenance for underground cable systems shall consider: inspection and/or testing programmes, maintenance programmes, and replacement programmes for components approaching the end of their serviceable life. NSW Department of Water and Energy, February 2009 Page 20 of 45

22 6.4 Maintenance of Substations Substation buildings, walls, fences, enclosures, associated plant, equipment and lines shall be maintained in a safe operating condition. A system of maintenance for substations shall consider: inspection and/or testing programmes, maintenance programmes, and replacement programmes for components approaching the end of their serviceable life. 6.5 Maintenance of Protection and Earthing Systems Protection and earthing systems shall be inspected and maintained in a safe and reliable operating condition. A system of maintenance for protection and earthing systems shall consider: inspection and/or testing programmes, maintenance programmes, and replacement programmes for components approaching the end of their serviceable life. Earthing systems shall be inspected and tested at intervals commensurate with risk of corrosion or mechanical damage to ensure that design requirements are met. The results of visual inspections and resistance to ground tests must be recorded and reviewed to identify any changes in results that should influence the frequency of inspection, tests and maintenance. The results of visual inspections and performance tests of protection systems shall be recorded and reviewed to identify changes that would influence the frequency of inspections, tests, maintenance and replacements. 6.6 Environmental Considerations The maintenance of electricity works shall take into consideration environmental issues and concerns. Factors to consider, include, but are not limited to: the minimisation of environmental damage, including visual impacts, tree management programmes, a reduction in and the correct disposal of waste products, and the consideration of Electromagnetic Field (EMF) issues. NSW Department of Water and Energy, February 2009 Page 21 of 45

23 7 SAFE ELECTRICAL WORK PRACTICES 7.1 General This Section applies to work on or near exposed electricity works, for which the Scope of this Code applies. The relevant documents referred to in the appendices to this Code should be considered for the operation of electricity works and work practices. Where there are variations between the documents referred to in Appendices A, B, C, D and E, and this Code, the Code is to take precedence. 7.2 Qualifications and Training General Requirements No work to which this Code applies shall be carried out unless the employee: has received training which is appropriate for the type of work concerned, and has been authorised by their employer after the training has been satisfactorily completed, is capable to safely perform the work required to be undertaken, has demonstrated competency of the relevant work procedures and safety instructions, and has during the previous 12 months, received appropriate instruction in the following procedures that are relevant to the nature of the work, resuscitation, releasing a person from live electricity works, rescuing a person from a pole, structure or elevating work platform, and rescuing a person from confined space. NSW Department of Water and Energy, February 2009 Page 22 of 45

24 7.2.2 Employer Responsibility The employer shall ensure that appropriate training courses have been undertaken by the respective employees so they can carry out the required tasks safely and competently. The following should be considered: accreditation of the courses, the relevance to the tasks to be performed, national competency standards or industry equivalent, the course syllabus, the facilities for training, assessment criteria for the issue of certificates, a linkage between in-school and on-the-job training, and whether the training provider has a Quality Assurance system in place and is listed in the National Register of quality training providers for utilities Employees in Training Employees undergoing training may undertake the work, subject to: it being safe to perform, and they are under continuous and close supervision of a qualified and experienced employee. 7.3 General Safety Provisions Basic Safety Principles All HV electricity works shall be regarded as live until isolated, proved to be de-energised, earthed and short-circuited, and an Access Permit issued according to the Network Operator s approved procedure. Alternatively approved live line working techniques shall be used. All LV electricity works shall be regarded as live until isolated and proved to be de-energised, in accordance with the Network Operator s approved procedure, otherwise approved safe live working procedures shall be used Hazard Identification and Risk Assessment All hazards shall be identified and the associated risks assessed, in writing, prior to working on or near any electricity works. The hazard identification and risk assessment system shall be regularly audited to ensure compliance Hazard Control Appropriate control measures shall be adopted for identified hazards, taking into consideration the associated risks. NSW Department of Water and Energy, February 2009 Page 23 of 45

25 7.3.4 Minimum Safe Working Distances No part of a person s body and no material or equipment not insulated for the voltage concerned must come closer than the following minimum safe working distances for live exposed electricity works specified in Table 4, unless specific procedures approved by the Network Operator, including fixing barriers or live working techniques, are utilised: TABLE 4 Nominal Voltage (U) (Volts) Minimum Safe Working Distance (mm) U < < U < < U < < U < < U < < U < U > Correct Labelling and Recording of Electricity Works All electricity works shall be clearly identified by labels, which shall be updated if any network alteration has taken place. Temporary labelling and danger tags are required as a warning against inadvertent and unauthorised operation of electricity works. Records, diagrams, maps and the like shall be kept as to the location, type and installation details Hazardous Electrical Occurrences or Effects The hazardous electrical occurrences or effects which can develop on or around electricity works are summarised under the following categories: lightning, induction, transfer voltage, voltage gradient, line energising, and neutral and earthing system currents. Precautions shall be taken to avoid danger from electrical occurrences or effects. NSW Department of Water and Energy, February 2009 Page 24 of 45

26 7.3.7 Precautions for Energisation and Re-energisation of Electricity Works Electricity works shall not be energised or re-energised unless: the employees are trained and authorised to carry out the energisation or re-energisation of the electricity works, all work on the electricity works is complete, all equipment (including testing equipment), plant, tools and materials are removed, all earths, short-circuits and equipotential bonds, if used, are removed, appropriate checks and tests are carried out to ensure safety, precautions are taken to ensure all persons are clear of the electricity works, and all relevant Access Permits are cancelled. Re-energisation of electricity works following an unplanned outage (protection operation) shall be carried out by trained and authorised employees in accordance with the Network Operator s approved procedures. Consideration shall be given to: the geographic location of the apparatus, the need for patrol and inspection, the time delay between the outage and the proposed try-back, and assessment of the associated risks, including any fire ban declarations. No electricity works shall be manually re-energised following an unplanned outage during total fire ban periods where the electricity works or part of the works to be re-energised is located within the total fire ban area until patrol and inspection has confirmed the condition of the electricity works First-aid Appropriate first-aid facilities shall be readily available for use in the event of injury to any employee Protective Clothing Clothing shall be worn which gives appropriate protection to the head, body, arms, hands, legs and feet when working on or near electricity works. NSW Department of Water and Energy, February 2009 Page 25 of 45

27 Work in Confined Spaces Work in a confined space shall be carried out in accordance with the Network Operator s approved procedures, and shall consider the following: an assessment of the hazards involved, authorisation for an employee to enter the confined space, an atmospheric check of the confined space before entry, and continual monitoring of the atmosphere while the confined space is occupied, and a suitable rescue procedure. 7.4 Operating Work All operating work shall be in accordance with the Network Operator s approved procedures which shall ensure: the safety of employees, the safety of the public, and the correct operation of the electricity works. 7.5 Access Permits A Network Operator shall ensure that there is an approved procedure for the issuing of access permits. An access permit shall: be issued and/or cancelled by an authorised person, only give access for work on electricity works which are safe to work on, only authorise work to begin when all employees are aware of: the electricity works to be worked on, the conditions under which the permit is issued (including any special precautions), and the existence of any remaining electrical hazards; and be cancelled after the work to which it relates has been completed. NSW Department of Water and Energy, February 2009 Page 26 of 45

28 7.6 Work on Low Voltage Electricity Works Work on LV electricity works, whether under live or de-energised conditions, shall be in accordance with the Network Operator s approved procedure De-energised LV Electricity Works Work on de-energised LV electricity works shall be carried out in accordance with the Network Operator s approved procedure, with due regard to the following: isolating the electricity works, taking precautions to ensure the electricity works remains de-energised, proving the electricity works is de-energised, clearly identifying the electricity works, defining the safe work area where appropriate, and taking additional precautions such as earthing and short-circuiting of electricity works and/or live working procedures where hazardous induced voltages are likely to occur Live LV Electricity Works Work on live LV electricity works shall be carried out in accordance with the Network Operator s approved procedure, with due regard to the following: that the electricity works has been identified as LV, that suitable precautions have been taken to avoid inadvertent contact with other live conductors or earth, and that the employee is trained in the safe execution of the work. 7.7 Work on High Voltage Electricity Works De-energised HV Electricity Works Work on de-energised HV electricity works shall be carried out in accordance with the Network Operator s approved procedure, with due regard to the following: isolating the electricity works, taking precautions to ensure the electricity works remain de-energised, proving the electricity works are de-energised, earthing and short-circuiting the electricity works, except for periods where testing is in progress, defining the safe work area where appropriate and the issue of an Access Permit. NSW Department of Water and Energy, February 2009 Page 27 of 45

29 7.7.2 Live HV Electricity Works Work on live HV electricity works shall be carried out in accordance with the Network Operator s approved procedure, with due regard to the following: that the employees are trained in the safe execution of the work, that all members of the working team are currently qualified, that the Network Operator s approved procedures are adhered to, and that the required minimum safe approach and working distances are maintained. The minimum approach distances for work on live HV electricity works are detailed in Table 5 below. These shall be observed, except where a procedure approved by the Network Operator is adopted for work directly on exposed conductors. TABLE 5 Nominal Voltage (U) (Volts) Minimum Approach Distance (mm) U < < U < < U < < U < < U < < U < Work on Overhead Lines In addition to the other requirements of this Code it is necessary to: identify the overhead line at the point where the work is carried out, check the soundness of poles or structures, and the employee shall not ascend a pole or structure which is found to have suffered deterioration or damage to a degree which may cause it to collapse, prevent the line in the course of erection from becoming energised, and safeguard employees against hazardous electrical occurrences or effects. NSW Department of Water and Energy, February 2009 Page 28 of 45

30 7.9 Work on Underground Cables Work on or near underground cables shall be in accordance with the Network Operator s approved procedures Cable identification Work shall not commence on any cable unless it has been: identified by a method approved by the Network Operator, in the case of a low voltage cable, identified as low voltage, and in the case of a high voltage cable, proved to be de-energised by a method approved by the Network Operator Precautions for Work on or Near Cables The following precautions shall be taken before working on or near cables: Identify and safeguard against the electrical hazards that are present on the site. These can include, but are not limited to, live electricity works, induced voltages and transfer potentials and the potential for faults on adjacent cables and joints. Identify and safeguard against the physical hazards that are present on the site. These can include, but are not limited to, lack of ventilation or suitable lighting, dangerous gases, confined working environment, high temperatures, traffic hazards and other services. An employee shall not physically handle a high voltage cable while it is live unless it is completely surrounded by an earthed sheath or screen, or both, and precautions are taken, where necessary, to avoid danger from induced voltages and transferred earth potentials. An employee shall not physically handle a cable, whether sheathed or screened or not, if its condition is suspect or doubtful unless the cable is proved to be de-energised. When excavating in the vicinity of live cables an approved safe working procedure shall be used. NSW Department of Water and Energy, February 2009 Page 29 of 45

31 7.10 Access into Substations An employee shall not enter an area in an electrical station where there are live exposed high voltage conductors unless the employee: is authorised to enter that area, or is accompanied by a person who is authorised to enter that area, or has been specifically instructed by an authorised person as to the area that can be entered, the dangers that exist and the precautions that must be observed Work in Substations Work in substations shall be in accordance with the Network Operator s approved procedures Tools and Safety Equipment The employer shall ensure that appropriate tools and safety equipment are used: All tools and safety equipment shall be periodically inspected and tested to ensure their safety for use. The employee shall use the appropriate tools and safety equipment provided by the employer. The employee shall inspect tools and safety equipment to check their serviceability before use. Any defective tools or safety equipment shall be withdrawn from service. The employee shall not use any suspected defective tool or equipment. NSW Department of Water and Energy, February 2009 Page 30 of 45

32 Appendix: Acts, Regulations, Australian Standards, Codes and Guides relating to the Design, Construction, Maintenance and Safe Electrical Operation and Work Practices for Transmission & Distribution Systems SECTION A: STANDARDS, CODES AND GUIDES RELATING TO OVERHEAD LINES AND SERVICES The standards and publications listed below (and any associated amendments) are relevant to this Code but do not necessarily represent all the standards that may need to be consulted in meeting the requirements of this Code. The publication dates for the reference documents listed below are correct at the time of publication of this Code, however they should be checked before use to ensure that they are still the most current and appropriate issue, and that all associated amendments are considered. Conductors Conductors - Bare overhead - Hard-drawn copper AS Conductors - Bare overhead - aluminium and aluminium AS alloy Conductors - Bare overhead - aluminium and aluminium AS alloy - steel reinforced Steel conductors and stays - Bare overhead : Galvanised AS Steel conductors and stays - Bare overhead: Aluminium clad AS Galvanised steel wire strand AS Insulated Cables Approval and test specification - Electric Cables - elastomer AS insulated - For working voltages up to and including 0.6/1kV Approval and test specification - Electric Cables - AS Thermoplastic insulated - For working voltages up to and including 0.6/1kV Approval and test specification - Electric Cables neutral AS screened - For working voltages up to and including 0.6/1kV Electric cables - XLPE insulated - Aerial bundled - For AS working voltages up to and including 0.6/1kV Mechanical fittings for low voltage aerial bundled cables AS Electric cables - Aerial bundled - Polymeric insulated voltage AS /11(12) kv and 12.7/22 (24) kv - Metallic screened Electric cables - Aerial bundled - Polymeric insulated - AS voltage 6.35/11 (12) kv and 12.7/22 (24) kv - Non-metallic screened Conductors - Covered overhead - For working voltages AS /11 kv up to and including 19/33kV NSW Department of Water and Energy, February 2009 Page 31 of 45