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Electrical Hazards Awareness Briefing Excavation and Trenching Module 5

Electrical Hazards Awareness Briefing Excavation and Trenching Module 5

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Electrical Hazards Awareness Briefing Excavation and Trenching Module 5

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  1. Electrical Hazards Awareness BriefingExcavation and TrenchingModule 5 EFCOG Electrical Improvement Project

  2. These tools must be used with care! EFCOG Electrical Improvement Project

  3. A laborer was burned and rendered unconscious when his jackhammer hit a buried 13,200 volt electrical power cable. Serious Injury at DOE Site when 13.2kV Cable Struck EFCOG Electrical Improvement Project

  4. Typical Tasks That Expose Personnel to Underground Power Lines • Construction site excavation • Jack-hammering • Well drilling • Landscaping • Trenching for piping • Fence installation EFCOG Electrical Improvement Project

  5. Excavation Program Elements • Designate a Competent Person to oversee all excavation jobs and train to understand the electrical hazard • Use written excavation procedure and excavation permit • Require an excavation/trenching checklist to be used in job planning • Require non-intrusive surveys of areas and develop an interference map of area • Ensure excavation planning requirements flow down to subcontractors EFCOG Electrical Improvement Project

  6. Electrical Hazard Identification • Perform detailed drawing and map review including original site drawings and recent project drawings • Understand that drawings and maps, however, may not be up to date or indicate all field routings correctly • Perform walk-down of site surrounding the excavation area and look for conduits and raceways that extend underground and could cross into the excavation work zone • Discuss excavation area with facility site knowledge • Look for new asphalt, manholes not marked on prints or disturbed soil to identify potential for unmarked interferences EFCOG Electrical Improvement Project

  7. Field Investigation • Perform non-intrusive surveys of excavation area using trained and certified utility locators • Mark surface with interferences and verify immediately prior to start of excavation • Know limitations of non-intrusive equipment • GPR has been off target by 3 feet and may not identify some interferences • Voltage proximity detectors are shielded by ground wire or conduit • Current proximity detectors will not detect if electrical load is turned off EFCOG Electrical Improvement Project

  8. Identifying Interferences • De-energize and lockout known electrical hazards-Don’t let schedule and convenience take precedent. • Hand excavate interferences within excavation limits • Look for different types of soil in the excavation area or for colored concrete that may indicate presence of underground electrical line • Consider use of vacuum excavation technology for uncovering interferences • Use caution when hand digging-even shovels and post hole diggers can damage direct burial cables EFCOG Electrical Improvement Project

  9. Identifying Interferences • Use appropriate PPE (voltage rated gloves and footwear) when identifying electrical interferences • PPE is important since detection of hidden utilities can not always be guaranteed • Use double-insulated electrical tools • Use fiberglass-insulated shovels and picks when excavating by hand • Use rubber mats as appropriate EFCOG Electrical Improvement Project

  10. Other Safe Practices • Stop work and call a time out if an unidentified obstruction is found during excavation • Revise maps and drawings to reflect actual found field conditions before closing excavation permit • Consider use of electronic drill stops when drilling in concrete (DOE Electrical Safety Handbook Section 11) • Observe all Power Line Right of Ways and notify power company prior to excavation EFCOG Electrical Improvement Project

  11. Conclusion • Remember, you can avoid the pain and suffering that can happen when you contact an underground energized electrical power line • Implement and follow the practices in this module • Stop work when in doubt EFCOG Electrical Improvement Project