Tree felling near powerlines in forestry operations
The following guidance is provided for Inspectors who engage with duty holders working near power lines. This could include tree felling operations, operating mobile plant and arboriculture operations.
This document is written specifically for our Inspectors and Managers and is provided publicly to assist those in the forestry industry understand how inspectors will approach assessing duty holders management of the risks associated with this activity. It is not intended as guidance for PCBUs, who we expect to operate to ensure people’s health and safety in accordance with relevant industry practices so far as is reasonably practicable.
Practice framework operational guidance
Who is this for?
WorkSafe Inspectors and Managers.
Felling trees near powerlines is a common practice in forestry operations. The additional risks associated with undertaking tree felling operations in close proximity to powerlines must be managed effectively. All reasonably practical steps in the circumstances must be taken to ensure the safety of workers.
When making any enforcement decisions inspectors must use the Enforcement Decision-Making Model (EDM) to determine the appropriate enforcement action to take.
Decision making factors
Inspectors are expected to use their judgement and discretion where the word ‘should’ is used in this Operational Guidance e.g. ‘The inspector should…’
Relevant legislation or regulations
APPROVED CODE OF PRACTICE FOR SAFETY AND HEALTH IN FOREST OPERATIONS 2012 (THE ACOP)
Provides practical guidance for PCBU’s, workers and all others engaged in work associated with forestry. Section 2.14 ‘WORKING AROUND LIVE POWER LINES’ provides specific guidance.
i. Section 2.14.1 reiterates to duty holders that power lines shall be treated as being live unless formally advised by a competent person or network representative.
ii. Section 2.14.2 makes reference to the Minimum Approach Distance (MAD) in accordance with the Approved Code of Practice for Safety and Health in Tree Work – Part 2: Maintenance of Trees around Power Lines 1996.
Note: Situations where the Forest Operations ACOP applies includes commercial forest harvesting and commercial felling of shelter belts. It excludes maintenance tree work outside of commercial forestry appropriately undertaken by utility arborists.
iii. Section 2.14.3 specifies the need for a felling plan to be agreed by the contractor, principal, and Asset/Network Owner (Power Company) for trees within two tree lengths of the powerlines.
APPROVED CODE OF PRACTICE FOR SAFETY AND HEALTH IN TREE WORK – PART 2: MAINTENANCE OF TREES AROUND POWER LINES 1996 (TREES CODE 2)
The Trees Code 2 is written primarily for arborists who conduct maintenance pruning in urban areas often near live powerlines. Utility arborists, engaged or employed by power companies for vegetation management, are provided with specific training to manage the risks associated with working near powerlines. (ref 1. General).
Note: Arborists have their own set of qualifications e.g. level 3 or above utility arborist with advanced tree falling unit
NEW ZEALAND ELECTRICAL CODE OF PRACTICE FOR ELECTRICAL SAFE DISTANCES 2001 (ECP 34)
The Electrical Safety Regulations - regulation 17 mandates Electrical Code of Practice (ECP 34) which is intended to cover all kinds of work around live lines, including work with mobile plant, but is more technical and not specific to particular kinds of work. It focuses on MADs and competence of workers in the context of work near electric lines, including structures such as towers and poles.
Electrical Engineers’ Association guides should be considered.
- EEA Guide to Electrical safety for forest and woodlot felling and logging operations(external link)
- EEA Guide for non-electrical industry employees using mobile plant near powerlines and electrical cables(external link)
Inspectors should assess each situation on its merits. Duty holders have a responsibility to provide sufficient information for inspectors to review when they are considering compliance action. Inspectors should:
- Engage with contractors and employees on site and take action appropriate to the situation
- Take note of the asset/network owner
Undertaking the work
The primary duty of care for the tree felling operation in most circumstances is the responsibility of the contractor undertaking the operation (HSWA section 36(external link)). The contractor must ensure all reasonably practical steps have been taken in the circumstances to protect workers from harm. This will include an effective risk identification and management control system. Workers must be provided with training, supervision and guidance.
Planning consulting and co-operating
Inspectors should expect to see an agreed felling plan that has been developed between the parties, including but not limited to the workers, contractor, forest owner and asset-/ network owner prior to starting. The PCBU who is best placed to control risks should generally lead planning decisions (HSWA section 30 to 38(external link)).
If the plan is not documented inspectors should make enquires to establish how the risks are being controlled and that there is agreement between all parties.
Contents of a tree felling plan
Inspectors should check that all aspects of the plan have been considered and that there are measures in place to manage/control any items not included.
The forest owner/manager or contractor usually will have an understanding of the requirements of a tree felling plan. They should understand the relevant skills and experience of tree fellers and machine operators that are required for the operation. Inspectors can ask how they have selected the equipment and mobile plant best suited to complete the task safely. The forest owner and asset-network owner should be guided by the skill and knowledge of the contractor. The contractor should have utilised skilled workers when they developed the felling plan with the forest owner and the Asset Owner/Lines Company.
The tree felling plan should include:
i. Person in control onsite
ii. Risk assessment and effective management controls normally associated with tree felling, in addition include the risks presented by the physical powerlines, the electrocution risk and any risks arising from the combination of these
iii. Competency assessment of all workers undertaking work near powerlines. Workers must be competent for tasks undertaken. Reference: Forestry ACOP Appendix 1: Definitions Competency and Competent person
iv. Mobile plant selection and operation methodology.
v. Information on the capability and limitations of the equipment and mobile plant selected for use
vi. Details of terrain and conditions to be accommodated
vii. The method of tree felling which will be used e.g. machine assisted tree felling: Pushing or Winch assisted pulling trees over.
viii. Risks associated with operating mobile plant operating near workers and powerlines must be effectively controlled. This must include the agreed safe approach distances for mobile plant and workers.
ix. Provide workers with all information required to ensure the operation can be undertaken safely. Includes detailed safe operating procedures, emergency procedures
x. Information advising procedures which should be followed in the event of a safety critical event such as a tree inadvertently falling onto powerlines
If any of these aspects have not been considered in the plan then this is a prompt for inspectors to ask more questions.
Managing the electrocution risk
PCBUs undertaking forestry operations have a duty to ensure that all electrocution risks are being managed whether elimination or minimisation strategies are being implemented.
When considering s34 the duty to consult includes the relevant electricity asset owners or operators (transmission, lines companies or generators) and other PCBUs (e.g. contractor, forestry workers and the Forest Owner) to ensure the management of the electrocution risk.
Inspectors should expect to see that the contractor, forestry workers and forest owner have been guided by the skill and knowledge of the electricity asset owner or operator.
Eliminate and minimisation of the risk of electrocution
Inspectors should ask duty holders if they have considered eliminating the electrocution risk.
The risks associated with electrocution must be eliminated if reasonably practicable in the circumstances. An example of where elimination, de-energising the powerlines is likely to be practicable is where:
- Trees are leaning heavily towards power lines. Mobile plant cannot access the trees due to steep terrain. The duty holders have decided the power lines will be de-energised, the power lines removed temporarily and trees felled in the direction of the lean. The trees would then be removed and the powerlines reinstated.
Where a plan is developed to minimise rather than eliminate the electrocution risk the PCBU needs to be able to explain and justify that decision.
Minimisation should only be used where elimination of the risks by de-energising the powerlines is not reasonably practicable in the circumstances.
Depending on the circumstances, the PCBU may have chosen one of several different methods of minimisation;
- Following the minimum approach distances in ESR regulation 17 and ECP 34,
- Using a feller buncher and skilled operator working within the MAD 4 or 6 metres of the power lines (with permission of the asset owner or operator),
- Felling the trees using machine assistance within the MAD 4 or 6 metres of the power lines (with permission of the asset owner or operator),
- using a qualified arborist to section the trees.
Regardless of the method used, the PCBU should have considered disabling any system that automatically recloses (re-livens) the line under fault conditions (eg auto reclosers),
The PCBU should be able to explain to the inspector why the particular method was chosen above other options and how the risks associated with the chosen method are being managed. The inspector may want to talk to several people to see if they all understand and are following the plan. This will test if the plan has been clearly communicated and understood.
The inspector could also ask if they have a process to manage variances to the agreed felling plan, for example by asking what happens if a worker is absent, equipment fails or adverse weather strikes.
How the PCBU may assess the risks
When an inspector asks the PCBU about risk assessment they may show them that they have used one of the following methods.
Tree rating system
A system which rates the trees of concern may be used to identify the risks associated with individual trees.
Each tree is rated from 1 to 5.
- The tree can be fallen without concern outside the two tree length zone.
- The tree is within the two tree length zone and outside a tree length plus 4 or 6 metre zone.
- The tree is within the danger zone (tree length plus 4 or 6 metres) but can be felled using conventional tree felling techniques. The faller must have a suitable machine available to provide assistance if required to fell the tree safely.
- The tree is within the danger zone, but assessed as difficult (includes edge trees) - the faller must use a machine to push/pull every tree over.
- The tree is within the danger zone and cannot be safely fallen using machine assisted tree felling. The tree will be left standing for a specialist to take down.
Use of Minimum Approach Distances
Focusing on the 3 distinct distances from the powerlines illustrated in the diagrams below will assist with management of the electrocution risks.
Minimum Approach Distances – MAD
- MAD ‘Competent Worker Zone’ Includes any branches which encroach into Radius A
- MAD ‘Any Tree Worker Zone’ between the MAD and 1 tree length + 4-6m (voltage dependent) from the powerline
- Two Tree lengths from the powerline(s) zone
Figure 1. Minimum approach distances for tree workers
Evaluating and monitoring the work
The PCBU should be able to explain to the inspector when and how they review their felling plan to ensure it is effectively managing the risks.
This may include the contractor contacting the forest owner and the electricity asset owner or operator to agree on any changes required to the plan or stopping the tree felling work near powerlines if the risks to workers cannot be effectively controlled.
What to look for to establish a breach
Worksafe Inspectors should look for evidence that:
- Elimination was the first consideration when determining the controls required to manage the risks
(All written material in respect of tree work around powerlines states this as the first reasonably practicable step). In the case of tree work around live lines, the risk of electrocution can only be eliminated by de-energising and grounding. PCBUs should have explored this possibility. If the electricity asset owner or operator agrees to de-energise and earth the lines, they need to provide the forest manager and contractor with the specific date, time, and part of the lines to be de-energised.
- If minimisation is used, the PCBU should be able to explain and justify the reasons why elimination of the risks by de-energising the powerlines was not reasonably practicable in the circumstances. Minimisation should include but is not limited to disabling any automatic reclosure system.
- If the powerlines are not confirmed as de-energised by the electricity asset owner or operator, the PCBUs and workers should be following the relevant approach distances. These are included in the tables in the appendix unless they have consent from the asset owner or operator.
- PCBUs should be able to satisfy the inspector that the risks associated with the chosen method are clearly understood and effectively managed. Inspector should look for detailed planning which describes effective controls of the risks and talk to several parties to see if the plan is clearly understood and being implemented.
The PCBU e.g. the contractor who has taken responsibility for documenting the plan should be able to explain how the risks are managed.
When WorkSafe Inspectors first visit sites where tree felling near powerlines is occurring there should be:
- A tree felling plan agreed by all parties
- A process to manage variance to the agreed tree felling plan. For example absent workers, equipment failure or availability, or adverse weather.
- Plans should document the consideration to Elimination of the Risk “Electrocution” in the first instance. Where elimination is not used the reasons should be recorded.
Discuss the plan and the work with workers engaged in the tree felling and machine operating tasks. It is critical workers engaged in the work understand the plan and have agreed the plan will ensure their safety.
If inspectors are taking enforcement they should obtain sufficient evidence to document their reasonable belief. An inspector can form a reasonable belief of the failure or likely failure in various ways, including by;
- Talking to duty holders, workers and witnesses, (C)
- Making observations, (O)
- Obtaining documentation, (D)
- Conducting Examinations (E)
- Taking photographs, sketches and measurements.
Enforcement Decision Scenario 1
(These scenarios are to provide examples of how EDM could be applied to common situations. They are not intended to provide a prescriptive template for inspectors to follow when they are in the field.)
An inspector visits a ground based logging operation who are working near powerlines. The main contractor has a detailed plan and there is a lines company representative onsite. It was not practicable to de-energise the lines. The tree feller onsite is competent and aware of the plan. However, there is a loader operator who is unaware of the potential electrocution risks. As a result, the loader is occasionally operating inside the minimum approach distances assisting the tree feller, pushing trees over. The contractor and the lines company representative explain that they had not considered the loader operator when drawing up the plan and had instead focused on the tree feller.
Actual Risk: When working inside the minimum approach distances the loader operator is at risk of electrocution. It is credible that death or severe injury would occur. With the loader working inside the minimum approach distances, it is not a surprise if this occurs. Therefore the likelihood is probable.
Benchmark Risk: Applying minimum approach distances are an administration control, which is a form of minimisation. They would not change the consequence, which is still severe, but they would reduce the likelihood to remote. They would not reduce the likelihood to Nil/negligible as they are not an isolation control and there is still a chance the loader may inadvertently breach the minimum approach distance.
Risk gap: substantial
Step 3: As the loader is currently operating there is a clear immediate exposure to the risk. Therefore the inspector follows the red pathway illustrated in Flowchart 1 of EDM.
Initial action: Assuming the risk gap cannot be addressed before the inspector leaves the site, a prohibition notice should be issued by the inspector. The inspector should also consider issuing an improvement notice for the underlying causes that have resulted in this risk. In this case it is likely that the risk identification and planning were not sufficient.
Applying Flowchart 3 may see an inspector also consider prosecution, depending on the main contractor’s duty holder factors.
Enforcement decision scenario 2
An inspector visits a logging operation using a swing yarder. The inspector noticed 110kV powerlines close to the harvesting area while he was driving to site. The trees are felled by a tree feller using a chainsaw. The swing yarder assists with pulling the trees away from the powerlines. He discusses this with the main contractor’s manager who says that they are “probably” not going to work in that area for two or three weeks. They decided not to contact the lines company as they will use a swing yarder to pull the trees over. The contractor says that when they fell the trees he will be with the tree feller and he was “sure” that no trees would hit the powerlines.
The trees are 35 metres tall. There are trees within 1 tree length of the powerlines.
Actual Risk: When working near the powerlines, the tree feller and machine operator are both at risk of electrocution. It is credible that death or severe injury would occur. Working in the way proposed, it would not be a surprise if contact with the powerlines occurred. Therefore the likelihood is probable.
Benchmark Risk: Eliminating the risk of electrocution should have been the first option. In this case, the main contractor has not discussed this option with the lines company to see if it is reasonably practicable. If elimination was reasonably practicable, then both the benchmark consequence and likelihood would be Nil.
Risk gap: Extreme
Step 3: With an extreme risk gap, the next step is to consider if the exposure to the hazard is immediate or imminent. In this case the inspector concludes after enquiries that it is possible that the contractor might begin the work near the powerlines early. As the work is foreseeable, the inspector decides that, if the work occurs, the exposure to the hazard is immediate or imminent and as a result follows the red pathway illustrated in Flowchart 1 of EDM.
Initial action: As the risk gap cannot be addressed before the inspector leaves the site, a prohibition notice is issued by the inspector. This notice prohibits tree felling work near the powerlines, not all tree felling onsite. The inspector also considers issuing an improvement notice for the underlying causes that have resulted in this risk. In this case, the main contractor should have consulted the lines company to meet their s34 duty.
Applying Flowchart 3 may see an inspector also consider prosecution, depending on the main contractor’s duty holder factors.
Example notice wording
Below is an example of wording that could be used on the prohibition notice for enforcement decision scenario 2.
Notice issued to: Duty holder (main contractor) – correct legal entity
Address: Address of the duty-holder – normally the address where their business is based
Details of person notice left with: The name and position of the person who the notice was left with and the address where you have given this person the notice.
Inspector name: The inspectors full name as it appears on the inspector’s identity card
Reasonable believe that, at the workplace specified below, an activity:
The workplace is: Address of worksite
Legislative provision: Health and Safety at Work Act 2015, section 36(1)(a)
Basis for believing grounds exist: Conclusion after enquiries that workers were planning to fell trees near the powerlines using a swing yarder to assist with the felling.
Matter or activity that gives rise or will give rise to the risk: Tree felling near powerlines.
I therefore prohibit the carrying on of the matter or activity in any way in the way specified below until an inspector is satisfied it has been remedied: any tree felling work within 39 metres of the powerlines. This being 1 tree length (35 metres) plus 4.0 meters MAD.
Recommended measures to remedy: Contact lines company and discuss the planned work and control options, including de-energising the power lines. Update tree felling plan and communicate to all workers and duty holders.
- Elimination (de-energising the lines) is always the preferred control, and PCBUs should first consult with the electricity asset owner or operator to arrange this.
- No two situations are the same, and so a one-size-fits-all enforcement decision is not appropriate.
- With the application of EDM WorkSafe New Zealand provides a consistent process across the country, even when the enforcement steps chosen are different from one inspector to another.
- The key, as always, is to ask what risk management and decision-making processes led to the work method and felling plan agreed to by the duty holders.
- And finally, if the plan does not ensure the safety of workers or if practice deviates from the agreed felling plan. For example:
- absent workers, equipment failure or availability, or adverse weather.
- If the plan is not being followed.
A new plan which effectively manages the risk to workers should be developed and agreed. If a suitable plan is not in use the work should not proceed.
Appendix 1: Minimum approach distances - MADs
There are some simple rules in the existing guidance about where and how work can be done around live lines.
- No felling should be done within two tree-lengths of live power lines without a felling plan agreed between:
- the contractor
- the forest owner/manager and
- the asset owner
This includes manual tree felling, machine-assisted tree felling and mechanised tree felling. The plan must identify the site specific risks associated with the work which will be undertaken. Plans must clearly communicate how the risks identified will be managed.
- No mobile plant should be used closer than 4 metres from the live lines without written permission from the asset owner (ECP 34, Trees Code 2,).
Consent for reduced minimum approach distances
ECP 34 lays out voltage-based MADs where no work of any kind should be undertaken except by a “competent employee”.
TABLE 9 Minimum safe approach distance limits for persons from exposed live parts (Where consent from the owner of the live parts has been obtained)
|Circuit voltage||Distance limits|
|Below 1 kV||0.5|
|220 kV and above||6.0|
ECP 34 defines a “competent employee” as an employee who can demonstrate the necessary knowledge, skills and experience to carry out electrical or telecommunications work in the vicinity of overhead electric lines, or exposed live metal, safely and to the standards used by the employer.
ECP 34 is aimed at linemen, utility arborists, and other workers who specialise in work on or around live lines. It was not originally intended for forestry workers, who are unlikely to be competent by the above definition.
It’s also unlikely that utility arborists of this type will be available or even qualified to fell many kilometres of forest within those MADs. Clear-felling is a skillset exclusive to experienced forestry workers.