Overhead and Underground Power Line Safety 1 Quentin Baker Director of Safety

Overview Background on power lines Hazards of overhead and underground power lines Injury prevention techniques Summary 2

Background Power lines transmit electricity Electrical current exposes workers to serious hazards –Most common hazard is electrocution –Most workers are unaware of potential electrical hazards Power lines can be –Overhead –Underground 3 Underground Utility Work

Background (cont) Some activities may cause interference with power lines – Overhead power lines Operation of a crane, forklift, and other construction equipment Changing street lights Tree trimming – Underground power lines Excavation Caution: Look out for overhead power lines when operating equipment 4

Types of Electrical Lines Electrical Cables –High Voltage, Low Voltage –Supervisory and Signaling Cables –Cathodic protection (cabinets, cables, earthing conductors, cable shrouds) Communication Cables –Phone lines –Coaxial cables (e.g. data cables) –Broadband cables –Tram traction cables and trolley wires –Railway supply cables and traction wires 5

Power Line Hazards 6 When unloading materials, watch out for overhead power lines Fire may be caused after overhead power lines are hit

Common Misconceptions Birds land on power lines, so they must be safe to touch - NO –Main objective of electricity is to reach the ground using the most direct route –Birds do not get electrocuted when they land on wires because they do not represent a path to the ground The power lines are safe for perching, but not when struck 7

Common Misconceptions Power lines are insulated, so they are safe to touch - NO –They are not always insulated Insulation deals with placing nonconductive material around the wire Insulation is a material that offers high electric resistance making it suitable for covering wires to prevent the possible future contact of adjacent conductors resulting in a short circuit –Just because a wire is weather protected does not mean that it is insulated Weather protection prevents water and snow from reaching the wire (and insulation, if used) 8

Common Misconceptions (Cont) Nonmetallic ladders are safe around power lines - NO –Wet ladders can be a conducting medium for electricity If power lines are not touched, they are safe - NO –Electricity can jump 9

Hazard Identification Conduct site investigation to identify existing conditions of: –Voltages of lines and equipment –Presence of hazardous, induced voltages –Presence and condition of protective grounds and equipment grounding conductors –Locations of electrical circuits and equipment –Maximum switching transient voltages 10

Dump truck operators should use caution when unloading materials near overhead power lines 11

Injury Prevention Techniques Stay away from power lines while working Maintain a safe distance OSHA’s “10-Foot Circle of Safety” rule Increase safe distance near higher voltage power lines 12 Maintain a safe distance from the Danger Zone (10 foot radius from the power line)

“In Transit” Clearances for Energized Overhead Lines Operation Clearances for Energized Overhead Lines 13 Nominal VoltageMinimum Required Distance (Feet) 0 to 50,00010 Over 50, inch for each 1,000 volt Nominal VoltageMinimum Required Distance (Feet) 0 to 50, ,000 to 345,00010 Over 345,000 to 750,000 16

Injury Prevention Techniques Recognize high voltage power lines – If unknown, the appropriate agency should be contacted Inform others about high-voltage power lines 14 Be aware of nearby high-voltage power lines

Injury Prevention Techniques Examine the site – Be mindful of power lines Search carefully around the site Look for lines not seen due to obstructions Alert others at the pre-job briefing Assume all lines are energized and potentially dangerous Make a safety clearance boundary –Portable safety barriers 15 HAZARD: Safe distance has not been maintained

Injury Prevention Use a spotter –Equipment operators have limited visibility –Get spotter’s help to stay clear of overhead power lines Spotter’s job should only require spotting and NOT guiding –Guiders may be at risk of electrical shock Especially when using a tag line 16 A spotter guiding heavy equipment operator

Injury Prevention 17 Working with tall equipment When working with tall and long equipment –Carefully plan and organize work with heavy equipment –Keep vehicles clear of power lines –Watch out for long objects –Adjust the position of equipment to maintain a safe distance from power lines

Injury Prevention 18 Down power lines are dangerous

Injury Prevention Fire caused by fallen power line 19 Fallen power lines can cause fires If a co-worker makes contact with a power line –Stay away –Protect yourself You could be shocked too if you touch someone who is in contact with electricity

Injury Prevention 20 If you hit a power line – In case of no immediate danger Move the equipment away Have someone call 911 Stay on the equipment until you know it is safe. Warn others to stay away – If you MUST get off the equipment, jump clear Crane hitting a power line

Underground Power Lines 21 Hitting a buried power, gas or communications line can cause – Injury –Excessive cost of repair Plan the work ahead Call the utility company With proper planning, these types of mistakes can be avoided

Underground Power Lines Locate and mark the perimeter of underground lines Exercise caution when excavating near power lines  Some manual excavation may be required Stay away from pad mount transformers –Green metal box 22 Underground utility line that has been hit

Tree Trimming Tree trimming may be dangerous if power lines are hidden in the foliage Trees that grow into power lines can cause unnecessary power outages Trees planted under or near power lines are potentially dangerous hazards Before tree trimming, check for the power lines Use proper equipment and trained personnel 23

29 CFR 1926, Subpart K – Electrical 29 CFR 1926, Subpart N – Cranes, Derricks 29 CFR 1926, Subpart O – Motor Vehicles, Mechanized Equipment 29 CFR 1926, Subpart P – Excavations Electrical Hazards Overhead Lines Underground Lines Applicable Standards 24

Summary… 25 Working in proximity of overhead and underground power lines is hazardous –Most common hazard is electrocution Workers should be aware of such hazards Several injury prevention techniques should be exercised to prevent injuries and fatalities –Need sufficient training to understand the hazards and practices for injury prevention –One of the best ways of hazard elimination is maintain a minimum safe distance Properly locate underground power lines before starting of work

Conclusion Thank you for attending today’s training, if you have questions for discussion I am available after the session or I maybe reached at: (336) Please make sure you signed onto the Training Roster. Remember: Plan your Work and Work your Plan 26