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Home > Electrical Safety > Law and penalties > Code of Practice for Electrical Work > Appendix B - Further Information > 2 Other electrical hazards to be addressed

2 Other electrical hazards to be addressed

2.1 Working in and around trenches, pits and underground ducts
2.2 Working with ladders, scaffolds, portable pole platforms
2.3 Working with elevating work platforms (EWP)
2.4 Working on or from poles and towers
2.5 Tagging out of service
2.6 Excavation near energised cables
2.7 Vegetation management, chainsaws and electrical workers
2.8 Use of tools

2.1 Working in and around trenches, pits and underground ducts

Sources of electrical hazards when working in and around trenches, pits and underground ducts include:

An effective safe system of work should address hazards of this kind.

Examples of suitable methods include:

Construction of high voltage cables varies. Some high voltage cables are oil filled, some are filled with gas, and others rely on insulation only. A cable that is leaking oil or gas should be treated as a high voltage cable.

2.2 Working with ladders, scaffolds, portable pole platforms

Work within the electrical industry requires extensive use of ladders, scaffolds and similar equipment. When using these items, you will encounter the three common electrical hazards from a number of sources including:

To control situations of this kind, a safe system of work should be used.

Effective control measures within this system of work should include:

2.3 Working with elevating work platforms (EWP)

2.3.1 Scope

This section provides electrical safety information for electrical workers when using Elevating Work Platforms (EWP), including scissor lift and boom type machines. It outlines hazards and risks associated with the use of an EWP only in an electrical context and does not cover general safe operation.

2.3.2 Hazards associated with EWP usage

Elevating work platforms are used throughout the electrical industry. Their configurations and applications vary widely, but there are common hazards and risks.

As the worker in the platform’s basket moves in the travelling end of the machine, the risk of coming into contact with exposed live electrical parts is relatively higher than for other forms of plant.

Sources of hazards associated with EWPs used for electrical and associated work include:

2.3.3 Working with an insulated EWP

If an insulated elevating work platform is used for electrical work, a risk assessment should consider whether the EWP’s insulation is capable of protecting a person from a current path through the machine.

The insulation does not protect a person from electric shock if it is possible for him/her to simultaneously touch any two parts with different electric potentials. In other words, if you are per forming live work in the basket of an insulated EWP, it is still possible to receive an electric shock. Refer to Figure 3.

Figure 3 – Example of an electrocution in an insulated EWP
Figure 3 – Example of an electrocution in an insulated EWP

Another example involves the application of earths and short circuits, such as portable earthing devices. In the case of portable earthing devices, you should address the likely effects of introducing potentials in or near the basket, as well as the mechanical effects of the conductors whipping about, should the device be applied to live parts.

Appropriate work practices should prevent different electrical potentials from existing in a basket. Situations like this can occur if people work on parts with different potentials, by an earth potential being introduced via a test lead, or through a portable earthing device, flexible extension lead or part of a structure.

2.3.4 Need for planning before electrical work using an EWP

Operations of EWPs with a boom length of more than 11m are deemed a Prescribed Occupation under the Workplace Health and Safety Act 1995 (PDF, 766 KB), as amended. Workplace Health and Safety provisions require certain minimum levels of training and assessment before the operator can gain the necessary certificate to engage in the occupation. The training, assessment and authorisation of EWP operators who are to work in an electrical context should be equivalent to, or better than, the Workplace Health and Safety requirements.

Before electrical workers perform any electrical work from an elevating work platform, certain safety issues should be addressed. These issues vary depending on the job, location, weather and so on. Though not exhaustive, the following list may be of assistance to determine suitability to perform work:

The EWP operator should ensure that all checks, inspections, set-up, stowage and maintenance requirements of the prime mover – as well as the EWP portion of the plant – are complied with. The checks, inspections, set-up, stowage and maintenance for each machine should be clearly documented. Though many of these requirements are similar to general EWP requirements, in electrical situations there are often additional requirements such as cleaning the insulating parts.

People should remain in the basket with their harness attached at all times when the basket is moved from the cradle. The only exception is when a documented safe system of work is in place to provide a safe alternative. If the safe system permits access or egress, or both, from an EWP basket in a raised position, this procedure must be followed to control the risks associated with this action. These risks include falls from heights and electric shock.

A safe system of work associated with electrical work from an EWP will invariably include training, assessment, authorisation and auditing components. Such components are general to machines as well as specific. Additionally, the safe system should consider at least the following:

2.3.5 Special provisions for working in the danger safety observer zone

What is the safety observer danger zone?

An elevating work platform is considered to be operating in the danger safety observer zone when there is a possibility that during operation:

Note: By virtue of the above definition, a elevating work platform is not operating in a safety observer danger zone when:

The safety observer danger zones for power lines on poles and on towers are illustrated in Figure 4.

Figure 4 – Safety observer zone for overhead power lines on poles or towers observer zone
Figure 4 – Safety observer zone for overhead power lines on poles or towers observer zone

Boom configuration

Boom configuration should also be addressed. Elevating work platforms used in the electricity industry include telescopic, ‘knuckle’ and scissor booms, fly jibs and hybrid versions. The appropriate boom configuration can assist or hinder electrical safety and needs to be addressed in risk management.

An example of a possible hazard can be seen in Figure 5.

Figure 5 – Example of a hazard due to the position of the vehicle and boom configuration (Worker performing de-energised work in an uninsulated EWP)
Figure 5 – Example of a hazard due to the position of the vehicle and boom configuration (Worker performing de-energised work in an uninsulated EWP)

Safety observer

A safety observer is required when an elevating work platform is operated within the safety observer danger zone as defined in section B.2.3.5. The employer of the EWP operator or a self-employed operator responsible for appointing a safety observer to observe the approach of the EWP or load to power lines.

People in contact with the EWP

When the elevating work platform operates in the safety observer danger zone, only the following persons may be instructed to touch, or allowed to touch, any part of the EWP or its load:

2.3.6 Additional loading affecting movement or position of the EWP basket

When considering the risks associated with working on or near structures, you should allow for the fact that the mechanical loading of the structure can be significantly altered. Examples: Adding additional light fitting to a light tower, or applying or removing tension from aerial conductors or catenary systems.

A mechanical failure of this kind can compound hazards and dramatically increase the risk and consequences. For example, if the tip loading of a pole is altered and a pole consequently fails, the falling pole may strike the EWP. At the same time, however, live mains may fall to the ground, creating hazards for work crew, rescuers and the public.

The elevating work platform should not be subjected to mechanical forces for which it is not designed. For example, inappropriate conductor tensioning techniques or raising and lowering with a power winch could apply inappropriate force to an EWP.

2.3.7 Possible illusions as a result of using an EWP

Operators should be aware of a feeling of light-headedness as clouds move in the background or affect the operator’s peripheral vision.

In addition, where work is performed near aerial conductors, operators should be aware of an illusion known as ‘wire blindness’. This state occurs when an operator knows that a conductor exists but either cannot see it or loses sight of it. In these circumstances, adequate contingencies should be employed.

2.4 Working on or from poles and towers

Sources of hazards when working on or from a pole or tower include:

Electrical work and associated work on or from a pole should be performed in line with an effectively implemented safe system of work.

Work should not begin until the pole has been examined and evaluated as safe to climb or work on. The requirement for an examination should apply regardless of:

As part of the examination and evaluation, a below ground inspection may be necessary.

Where the tip loading is being altered, work procedures should include methods that will prevent structural failure. Further, an engineering assessment should be conducted if the tip loading is to be altered permanently or where work procedures cannot ensure structural stability. If loading of a pole is altered consideration should be given to the effect this may have on adjacent poles.

Structures and insulators supporting live high voltage conductors should be checked to identify conditions that may result in leakage through the pole. Where leakage is suspected, further tests should be done to determine whether the structure is safe to climb.

2.4.1 Work practices

A safe system of work that is effective in ensuring electrical safety should ensure at least the following:

The following precautions should be taken when poles and towers are worked on:

2.4.2 Wooden poles

For wooden poles owned by an electricity entity, the examination should include a check for markings such as "suspect" (one diagonal painted stripe) or "unserviceable" (painted cross). For other poles, workers should consult the asset owner or operator. Fungus and loose sapwood should not obscure these markings.

Structural integrity can be checked by using an appropriate method such as a rope test. Where a rope test cannot be safely or practically completed, a suitable procedure for identifying pole defects should be used.

If a pole is not marked as suspect or unserviceable, it should be tested to ensure that the pole is safe to climb or access. In this case, the following tests should be considered:

During these tests, appropriate action should be taken to ensure co-workers and others are safe from falling objects etc.

A ‘ladder test’ – or any other method of testing a pole by imposing pressure via a ladder – should not be used as an appropriate way of determining if a pole is sound.

2.4.3 Concrete poles

Concrete poles are conductive, especially when wet. The conductivity occurs both through metal fittings connected to the reinforcement and through the concrete surface. Therefore, the surface of a concrete pole and all metal work bolted, clamped or bonded to a concrete pole should be treated as conductive. Take appropriate control measures such as using barriers and insulated mats.

2.4.4 Steel poles

With steel poles, internal and external corrosion can create the risk of structural failure. Inspection and testing should include any signs of corrosion-induced structural damage.

This should include the following tests:

During these tests, appropriate action should be taken to ensure co-workers and others are safe from falling objects etc.

Steel poles have various shapes and sizes. Safe work practices when using a ladder and pole platforms need to ensure that the devices can be fitted soundly. Safe work practices should include preventing people from falling from heights.

2.4.5 Working on unserviceable or suspect poles

In some cases, additional strengthening and support may not be installed before work is done on a "unserviceable" or "suspect" pole. When this happens, an appropriately experienced and qualified person should evaluate the pole’s condition to decide whether the pole can be safely climbed, worked on, or both. Additional measures to ensure safety may include:

Pole buoys or pikes may provide a satisfactory temporary means of supporting badly deteriorated poles. When a pole has to be climbed, pole buoys require additional staying if used for support. Otherwise, pole buoys are not suitable for the task.

When releasing conductors from an unserviceable pole, hold the conductors under control and release them slowly so that you can note their effect on the pole before you release them completely. If pole stability depends on the conductors being released, additional stays should be installed to maintain or increase stability.

If the pole cannot be held or supported so that all the conductors can be safely removed, no attempt should be made to climb or work on the pole until it is safe to perform the work. The pole should be made as secure as possible with available equipment.

2.4.6 Electrical leakage procedures for poles

Before climbing any pole supporting live high voltage conductors, make a visual inspection for any evidence of leakage. If you see evidence of pole top fires or other fire damage, damaged or polluted insulators, or a conductor, tie wire or debris touching the pole or cross arm, you should ensure the pole is tested or inspected for damage or both.

When conductor attachments cannot be clearly assessed from the ground because of wet weather or poor visibility, a detection/inspection should be carried out.

Where leakage is suspected on poles supporting broadband communication cables (BBCC), appropriate procedures should be used to detect leakage. These procedures should address the hazards associated with testing near exposed high and low voltage conductors. They should also look at whether any leakage through a BBCC supporting conductor might affect the detection’s validity.

Where leakage is suspected, work should not be carried out until the pole has been confirmed safe to work on or from.

Figure 6 – Rope pull test
Figure 6 – Rope pull test

2.4.7 Rope testing

The following items should be addressed when performing a rope test on a pole:

2.5 Tagging out of service

When equipment, parts or devices are not to be used, the item or items should be made safe (eg isolated) and tagged out of service. Examples of where tagging out of service should occur include:

Tagging out of service is a control measure that physically excludes items from use and should form part of a safe system of work. Tags used should comply with an appropriate standard.

Refer to also section 5.4.2.2.

2.6 Excavation near energised cables

Workers involved in excavation should be aware of the possibility of electric shock and explosions associated with damaged underground cables. It can be difficult to tell the difference between high voltage and low voltage cables. There is a potential for injury and death if low voltage and high voltage cables are damaged.

Even earthed, metal-sheathed cables can cause injuries if damaged, because protective systems may not always operate fast enough to prevent injury.

2.6.1 Precautions before excavation

Before excavation, you should contact the organisation, "Dial Before You Dig"23, a free enquiry referral service for information on underground assets anywhere in Australia. For further information, contact Dial Before You Dig by any of the following methods:

2.6.2 Using mechanical excavation equipment

A safe system of work should determine beforehand how close machinery, such as backhoes, excavators, horizontal borers and chain diggers, can excavate near:

If it is necessary to excavate near the items above, the work should be done by hand excavation or with hand tools.

The plant operator should be guided by another worker positioned to warn the operator if the machine appears likely to venture too close or to cause damage.

Pneumatic or other powered excavation tools, such as jackhammers, should not be used near conduits that contain live cables.

When using powered tools to excavate beside or around direct-laid cables in rock or hard fill, existing cables should be protected in case the machine slips.

2.6.3 Excavating concrete-encased conduits

Excavating concrete-encased conduits containing live cables can be hazardous if appropriate precautions are not taken. Explosions and electric shock can result.

It is preferable to remove cables from the conduit while the work is done.

If the cables cannot be removed, they should be de-energised. Hand excavation should be used, at least until enough of an opening has been made in the conduit to permit the installation of mechanical protection.

2.7 Vegetation management, chainsaws and electrical workers

If an electrical worker is required to perform vegetation management near exposed live parts, a number of additional hazards should be managed. Typically, this work ranges from clearing vines that have grown into a switchboard to trimming trees to maintain clearances from overhead powerlines.

In addition to hazards associated with general vegetation management and chainsaw use, electrical hazards include:

2.8 Use of tools

Poor use of tools can expose workers to electrical hazards including:

These tools should be used according to manufacturer’s instructions and an effective, safe system of work.

Tools should be restrained at the work position to prevent them from falling into live switchboards or jamming controls eg in an EWP. The use of lanyards around wrists, tool holders and tool restraints including tool pouches and baskets, should be addressed.

Refer also to section 6.4 for further information on tools, instruments and equipment.

22 Insulation must at least be effective against the maximum voltage of the particular overhead power line. The employer or self-employed person operating the crane is responsible for ensuring the effectiveness of the insulation in accordance with the relevant Standard.
23 Dial Before You Dig contacts member asset owners who have services at or near the proposed excavation site and will arrange for information about these services to be sent. Asset owners will usually respond within two working days and may provide copies of underground service plans. It must be emphasised that Dial Before You Dig is a referral and information service only and is not the legal owner of site information. Dial Before You Dig does not go on-site and find the physical location of the underground service.

Last updated July 16, 2009