Transmission Substation Field Instructions

Transcription

1 4.3 Substation Clearances Purpose This instruction describes the Safe Approach Distance from live electrical apparatus when working in an electrical substation. It supports the requirements detailed in the Electrical Safety Standards. Scope This instruction shall apply to all Horizon Power Workers working in Horizon Power substations who are instructed or Authorised Persons, to maintain Substation clearances. The personnel covered by this instruction are, operational personnel, non-operational personnel, visitors and including Workers operating, servicing, and/ or maintaining (MPS) Micro Power Systems electrical equipment. Safety Before commencement of work, a risk assessment must be carried out using the Risk Analysis Procedure (OSH ), to identify and document the hazards and risks associated with the task and ensure appropriate control measures are implemented. It is important that, appropriate control measures must be identified, documented and implemented in order to control hazards to As Low as Reasonable Practicable (ALARP). Instruction For all work in the vicinity of live electrical apparatus organisational procedures and instructions shall be used in conjunction with the use of Instructed or Authorised Persons. Safety Approach Distances Safe Approach Distance (SAD) is based on an Exclusion Zone principle. This principle defines an area around live electrical apparatus as shown in Figure 1, into which no part of the person, mobile plant or object (other than approved insulated objects) may encroach unless in accordance with an Electrical Access Permit. Work practices shall be applied to ensure persons, mobile plant and unapproved objects do not encroach on the SAD. These work practices should include: Working with the Exclusion Zone beyond reach of the mobile plant, equipment or worker; and The use of controlled movements. Necessary approach to live electrical apparatus shall be kept to a minimum and shall be restricted to the period required to perform the work. CS# FI 4.3 Substation Clearances Page 1 of 6

2 Figure 1 Exclusion Zone Principle Note: Encroaching into the Exclusion Zone is considered the same as touching live parts The SADs specified in Table 1 are based on work from a stable surface. Voltage Persons Working Mobile Plant Vehicle kv Instructed Persons and Authorised Persons Operated by Instructed or Authorised Person and Safety Observer Assigned Uninsulated Insulated Under the control of Instructed or Authorised Person Sections Sections 22/ Application Table 1 Safe Approach Distances (Note: All distances are millimetres) Based on the outcomes of a risk assessment an Electrical Access Permit or a Vicinity Authority permit will need to be issued if a person or mobile plant is working around live electrical apparatus. Electrical Access Permit An Electrical Access Permit shall be issued if the person is working or mobile plant is operating near live electrical apparatus. Information on an Electrical Access Permit is found in Field Instruction 6.21 Work Permits. Vicinity Authority Permit A Vicinity Authority permit shall be issued if the person is working or mobile plant is operating in the vicinity of live electrical apparatus. A Safety Observer shall be used if a Vicinity Authority work permit is issued. Information on a Vicinity Authority Permit is found in Field Instruction 6.21 Work Permits. CS# FI 4.3 Substation Clearances Page 2 of 6

3 Note: Persons working or mobile plant operating in the Vicinity of live electrical apparatus allows the person to work or mobile plant to operate up to the SAD for the specified voltage Figure 2 Working Around Live Electrical Apparatus Safety Approach Distances Instructed or Authorised Persons The person shall ensure that no part of their body or an extension of their body (tools, equipment and materials held by the person) approaches closer to live electrical apparatus than distances in Table 1 unless in accordance with an Electrical Access Permit. The person shall apply controlled movements or beyond reach principles to avoid encroaching the SAD. Figure 3 Example Application of SADs - Persons CS# FI 4.3 Substation Clearances Page 3 of 6

4 Safety Approach Distances Mobile Plant The Instructed or Authorised Person operating the mobile plant shall ensure that the mobile plant, its equipment and load do not approach closer to live electrical apparatus than the distances in Table 1 unless in accordance with an Electrical Access Authority work permit. Mobile plant shall only be operated in the vicinity of live electrical apparatus after precautions appropriate to the particular circumstances have been considered and action taken to control the associated hazards and risks. The control measures to be considered within a risk assessment should include: Positioning the mobile plant such that the SAD can be maintained in all circumstances. The use of Safety Observers and barriers and signs. The use of other precautions such as physical restrictions or control devices in conjunction with barriers. Mobile plant shall only be operated by an Instructed or Authorised Person when operating in the vicinity of live electrical apparatus. Appropriate allowance shall be made for any uncontrolled movements of mobile plant due to any reason. When mobile plant is operated from outside the mobile plant, precautions shall be taken to protect the operator from hazardous step and touch potentials. When mobile plant is working in the vicinity of live electrical apparatus, the mobile plant shall be earthed in accordance with Field Instruction 2.13 Vehicle and Plant Earthing Requirements. Figure 4 - Example Application of SADs Mobile Plant CS# FI 4.3 Substation Clearances Page 4 of 6

5 Safety Approach Distances Vehicles The person in charge of any vehicle, excepting mobile plant when in working mode, shall ensure that no part of the vehicle or its load approaches or is placed within the distances shown in Table 1 unless in accordance with an Electrical Access Permit. Handling Objects and Loads Figure 5 Example Application of SADs - Vehicles When objects are being handled manually or by mechanical equipment, care shall be exercised to prevent the objects or the mechanical equipment infringing SAD. For manual handling, appropriate work methods and an appropriate number of persons shall be used to maintain the SAD. For mechanical handling where there is a risk of encroaching the SAD to live electrical apparatus, the movement of loads shall be controlled by means of approved non-conducting ropes or other approved means. No person, other than the mobile plant operator shall contact the load, mobile plant or any attached conducting objects. CS# FI 4.3 Substation Clearances Page 5 of 6

6 References Occupational Safety & Heath Act 1984 Occupational Safety & Health Regulations 1996 SHMS OSH Job Risk Analysis (JRA) Procedure SHMS OSH Personal Protective Equipment SHMS OSH Mobile Plant and Equipment SHMS OSH Elevating Work Platform Procedure Electrical Safety Standards Field Instruction 2.6 Worksite Clothing / Personal Protective Equipment Requirements Field Instruction 2.13 Vehicle and Plant Earthing Requirements Field Instruction 2.17 Safe Approach Distances Field Instruction 2.23 Job Hazard and Risk Management (JRA) 4.1 Substation Entry Requirements Field Instruction 8.3 Induced Voltages Field Instruction 8.21 Work Permits ENA NENS National guidelines for safe approach distances CS# FI 4.3 Substation Clearances Page 6 of 6