Disconnect low voltage underground cables and apparatus in the power industry 

Overview

This standard is about disconnecting low voltage underground cables and apparatus in an electricity power utilities environment.  This could apply to both electrical transmission or electrical distribution networks and could typically apply to voltages from low voltage (LV) up to and including transmission voltages of 33,000 volts. Networks could be aligned with systems using traditional or emerging energy technologies.

This standard includes confirming instructions, carrying out risk assessments, checking the point of disconnection, checking there is no connected load, disconnecting cables and apparatus, testing and checking disconnections and completing documentation.

This standard is for crafts persons or technicians working for network owners or operators or their sub-contractors who are responsible for disconnecting low voltage underground cables and apparatus on electrical networks.  This could be carried out by people with different levels of network operational authorisation, but in each case, they will be required to have the degree of supervision which is required for their individual level of authority.

Performance Criteria

You must be able to:

  1. identify work location using system information in line with organisational procedures
  2. carry out all work within the remits of own authority and under the supervision of suitably authorised personnel when required
  3. receive and confirm instructions about disconnection activities to be carried out in line with organisational procedures
  4. carry out site specific risk assessments of work areas and condition of cables and apparatus to be worked on, identifying hazards and required control measures in line with organisational procedures
  5. check that a point of disconnection has been identified that complies with organisational safety procedures and takes the position of other cables and apparatus into account
  6. check that there is not a connected load before commencing disconnection activities and the system is confirmed as safe to work on in line with organisational operational safety rules
  7. communicate the status of cable and apparatus disconnection to affected parties and designated people when required and in line with organisational procedures
  8. use approved plant, apparatus, tools, equipment and consumables for cable and apparatus disconnection in line with organisational procedures
  9. work in line with health and safety, environmental and other relevant regulations, directives and guidance at all times
  10. disconnect cables and apparatus in line with workplan, safety instructions and organisational procedures
  11. carry out testing procedures before, during and after cable and apparatus disconnection in line with organisational procedures
  12. check completed disconnections comply with organisational specifications and no damage has occurred to nearby cables or apparatus for power or other utilities
  13. complete documentation for cable and apparatus disconnection in line with organisational procedures
  14. confirm completed disconnection meet safety requirements before reenergisation of the network
  15. leave work areas and disconnected cables and apparatus in a safe condition in line with organisational procedures
  16. deal with network issues and complications in line with safety and organisational procedures
  17. escalate issues that you cannot resolve to the designated person in line with organisational procedures when required

Knowledge and Understanding

You need to know and understand:

  1. Electrical power principles including three phase alternating current and direct current theories; voltage; types of earthing system on the LV network; dynamic and static engineering systems; application of electrical and electronic circuit theory and interfaces between the system voltage
  2. Electricity network design, construction, capabilities, complexities, operations, boundaries, topologies and control boundaries
  3. Apparatus which makes up the transmission or distribution network and the design, operation, function and limitations of transmission or distribution plant and equipment, substations, transformers, overhead lines, switchgear and auxiliary equipment
  4. Standard terminology, abbreviations and nomenclature in relation to cable and apparatus identification, and jointing and disconnection techniques
  5. The regulatory requirements associated with safety while carrying out work on power networks on low voltage underground cables and apparatus
  6. Organisational safe systems of work control measures for working on cable that have been made dead, isolating cables, proving dead, cables becoming live from alternative sources, screening from live equipment
  7. How to assess the location, size and condition of site, trenches and excavations and safe procedures for access, egress and working in confined spaces
  8. The general and inherent dangers of working on low voltage electrical systems on live and deenergised networks and required measures to address them
  9. Organisational procedures and safety instructions for receiving and confirming operational, network related instructions in normal and fault conditions, including remote and emerging technological advances
  10. The principles of pre task and point of work dynamic risk assessment, when they are required and how to carry them out and record findings
  11. The implication of cable condition on cable disconnection activities and techniques to identify the condition of cables
  12. The implications of disconnection activity for nearby cables and apparatus including those belonging to other utilities
  13. Who to notify about network related operations, when to notify them and organisational procedures for doing so
  14. Electricity network principles of operation of underground networks in normal and fault conditions and associated protective devices and their indicators in the event of system fault scenarios
  15. Sources of system information and how to interpret them to identify cables, apparatus, points of isolation, earthing arrangements and network running arrangements including system schematic diagrams, geographic records, work instructions, fault logs, protection data
  16. The sequence of processes, procedures, stages and operational safety rules relating to cable disconnection including considerations for identifying points of disconnection and verifying that there is no connected load
  17. The environmental impact of disposal, organisational decontamination procedures and what to do if things go wrong, including the use of spill kits
  18. The approved plant, apparatus, tools, equipment and consumables required for disconnection and how to obtain, inspect, prepare, carry out pre-use checks, use, maintain and store them
  19. Company specifications for jointing straight, branch transitions or pot ends and parallel networks for low voltage cables including for polymeric based cables, paper insulated mains cables and other legacy cable types and apparatus
  20. Safety, earthing, bonding, cable protection and joint protection materials and where and when they should be applied to prevent moisture and ingress
  21.  The purpose of visual, functional and electrical checks and tests for cables and apparatus, including at service termination, when they are required and how to carry them out, including for insulation, continuity, voltage, polarity, earth loop impedance, phase rotation
  22. Organisational procedures and systems for recording and storing operational information and to meet cybersecurity and data governance requirements, including role-based access, secure storage, audit logging, data retention
  23. The route to authorisation and supervision at different levels and the training, experience and certification required for your role