Safety in Overhead Transmission Lines maintenance work - EHS

When working near or on overhead transmission lines, manage the risks if you intend to work within a distance of 10 m, measured at ground level horizontally from below the nearest wire. Going close to a live overhead line can result in a flash-over that may kill and therefore, proper planning, Risk assessment and consultation with interested parties before and during any work close to overhead transmission lines help to reduce the risk of accidents.

Safety in Overhead Transmission Lines maintenance work

Not only accidental contact with live overhead power lines kills people but the people are also harmed when a person or object gets too close to a line and a flashover occurs. 

This is general safety guidance for overhead transmission lines and manage safety during its maintenance work will definitely help to both peoples who want to work near or on overhead lines where there is a risk of flash, arc or contact with the wires. This will also help to identify the safety measures to prevent contact with them.

Try to avoid work in close proximity to live overhead lines but if there is no alternative then it can be done only when the risks are acceptable and can be properly controlled.

Touching a power line is not necessary for danger; voltages lower than 230 volts can kill and injure people, even electricity can bypass wood, plastic or rubber, if it is damp or dirty, and cause fatal shocks.

 

How to Manage safe work on Overhead Transmission line

Risks of accidental contact or close proximity to the power lines are adequately controlled by risk assessment. Based on nature of job and Risk assessment, safety measures must be implemented even when work near the line is of short duration.

Here are the combine measures to achieve the Safety while working on or near to overhead power transmission line.

1. Planning and preparation
2. Eliminating the danger
3. Controlling the access
4. Controlling the work

 

General Safety Tips for working on live overhead transmission line

In case there is no options to isolate the overhead power transmission line and need to carry out the work near it, you must think about how the work can be done safely. Conduct a Risk assessment and If it revealed that the job cannot be done safely, it should not be done at all.

Risk assessment must include

1. The consideration of voltage and height of transmission line from the ground.

2. The nature of the work and its exact location i.e. whether close to or underneath the overhead power line.

3. Whether lifting equipment requires for man movement and details or it reach.

4. Whether access is needed underneath the wires

5. Availability of free space between the wires and the machinery or equipment or structures being erected.

6. The site conditions

7. The competency of involved manpower.

After assessing the risk, safety control measures must be provided and assure throughout the job. Appropriate PPEs and safety caution signages must be assured.

 

Overhead transmission line - General Safety Tips

1. Safety clearances for overhead lines must be maintained.

2. While using mechanical means in the Vicinity of Electricity Overhead Lines, establish an exclusion zone around the line and any other equipment that may be fitted to the pole or pylon.

3. The minimum extent of these exclusion zones varies according to the voltage of the line, as follows:

• For a low-voltage line – 1 m
• For a 11 kV and 33 kV lines – 3 m
• For 132 kV line – 6 m
• For 275 kV and 400 kV lines – 7 m

4. Under no circumstances must any part of mechanical appliances or equipment such as ladders, man basket, cage, poles and hand tools be able to encroach within these zones.

5. Always consider safety margin by allowing uncertainty in measuring the distances and for the possibility of unexpected movement due to wind conditions.

6. Carry long objects horizontally and close to the ground, assess the exclusion zone and then only erect or use.

7. Position vehicles such as Chery picker so that no part can reach into the exclusion zone, even when fully extended.

8. Machinery such as cranes and excavators should be modified by adding physical restraints to prevent them reaching into the exclusion zone.

9. Insulating guards and/or proximity warning devices must be fitted to the appliances.

10. All involved workforce must understand the risks and are provided with instructions about the risk prevention measures

11. This work must be directly supervised by competent person who is familiar with the risks and can make sure that the required safety precautions are observed.

12. If you are in any doubt about the use of exclusion zones or how to interpret the ENA document, you should consult the owner of the overhead line.

13. Provide ‘Inverted U’ barrier with caution board written with fluorescent color on both the sides of road so that it is visible during night hours, wherever high voltage transmission lines cross the road.

14. Under no circumstance rod, pipes or other similar material should be there within the flashover distances of high voltage transmission line.

15. No material, earth work or agriculture produce shall be dumped or stored, and plants/trees grown below or in the vicinity of overhead transmission lines so as to reduce the requisite safety clearances.

16. No waste shall be burned under the overhead lines.

17. Avoid extra-high voltage overhead transmission lines, crossing each other as far as possible. But if it is required, it should be erected by keeping standard clearance as per statutory requirement.

18. Provide shield wire/ground wire with overhead lines to protect against lightening.

 

Safety tips for overhead transmission line maintenance work

1. Obtain an appropriate work permit before beginning any maintenance work on an overhead transmission line.

2. Check using approved devices such as a grounding stick in the presence of the permit transmitter to see if the line is de-energized and effectively grounded.

3. Make sure that the ladder being used for the job is the correct size, with a suitable base or attached correctly and / or someone is holding it in position.

4. Wear full safety harness, electric gloves and helmet when working on overhead transmission line towers / poles etc.

5. Do not stand directly under the post when men are working on the top.

6. Do not work on overhead lines during thunderstorms, lightning or heavy rain, except in an emergency.

7. Check the condition of the ropes before using them on a pole / tower.

8. Divert vehicles and pedestrian traffic while performing work on public roads or displaying warning signs or flags. Keep a man at crossings to warn vehicles and pedestrians if necessary.

9. Keep all persons a safe distance away after completion of maintenance work and ensure that all tools are removed prior to return of permit to energize line in accordance with LOTO.

 

Summary

While working on or near to overhead transmission lines, manage the risks by providing appropriate measures after carefully assessing the exclusion zone. There is always chance of flash-over within an exclusion zone that may kill the person during any work close to overhead transmission lines.

This general safety guidance for overhead transmission lines and manage safety during its maintenance work will help to prevent accidents while working near or on overhead lines where there is a risk of flash, arc or contact with the wires.