Back to basics: How to reduce electrical hazards in industrial workplaces

 

 

Electrical hazard insights

• The risk of electrical hazards in industrial workplaces encompasses potential dangers such as electric shock, arc flash and arc blast, which can result in severe injuries including burns, cardiac issues and trauma.
• Employing the hierarchy of controls model, prioritizing measures like elimination and substitution over administrative controls and personal protective equipment, can significantly mitigate these risks according to standards like CSA Z462:21 and NFPA 70E, although the latter measures are often necessary to manage remaining hazards effectively.

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Industrial workplaces can present a variety of electrical hazards. Electric shock can result in internal and external burns, cardiac problems, seizures, muscle contractions and difficulty breathing. Additionally, there is the risk of arc flash, leading to severe burns, eye injuries and hearing loss and arc blast, which can cause acute internal and external trauma.

Electrical incidents can also lead to other modes of injury, including falls, especially if an incident occurs while working at heights. Given the severity of the injuries that can be sustained during electrical incidents, it is critical for firms to implement risk mitigations and for workers to practice safe work procedures to reduce the likelihood and severity of harm.

The hierarchy of electrical hazard controls

This article delves into the hierarchy of controls model used in CSA Standard Z462:21: Workplace Electrical Safety and NFPA 70E: Standard for Electrical Safety in the Workplace. This model recognizes six categories of hazard mitigation strategies, which are ranked according to effectiveness.

• Elimination: The most effective measure is elimination, which removes the existence of a hazard in the workplace.

• Substitution: Substitution replaces the hazard with a less severe or more manageable condition.

  Engineering controls: Engineering controls aim to isolate the worker from hazards through the design of the plant, equipment or process they interact with.

  Warnings: Warnings are designed to indicate the presence of hazards that remain after the first three mitigation approaches are applied.

  Administrative controls: Administrative controls are procedures designed to encourage safe work practices.

  Personal protective equipment (PPE): The last line of defense is PPE, which refers to items worn by personnel to protect them from workplace hazards.

A well-designed safety program will address hazards with the highest practical control level in the hierarchy and may use a combination of controls to address a single hazard.

1. Elimination

Elimination represents the highest tier of the hierarchy of controls. This strategy involves removing the hazardous condition from the workplace entirely, thereby preventing any possibility of an electrical incident. Elimination is an entirely effective mitigation method, resulting in no residual risk. It stands as the gold standard in the hierarchy of controls.

However, given the nature of modern industrial facilities, it is rarely a feasible strategy for addressing electrical hazards.

2. Substitution

Substitution is the second tier in the hierarchy of controls. This strategy involves replacing a hazardous condition with something that is less hazardous or more easily mitigated using other controls.

For example, a plant designer might choose to replace conventional switchgear with arc-resistant designs, which divert the energy of an electric arc away from personnel and decrease the risk of injury in an electrical incident. Other common substitutions include replacing line voltage control systems with power-limited or low-voltage designs to reduce the severity of electric shocks and substituting power tools with battery-operated models to eliminate the risk of shock from damaged extension cords.

3. Engineering controls

Engineering controls constitute the third tier in the hierarchy of risk management strategies. Although they do not remove or directly reduce the unsafe condition, engineering controls isolate workers from hazards through the design of the plant, equipment or processes with which they interact. A prevalent engineering control in electrical systems involves the insulation and guarding of energized components, which may include mechanical barriers and interlocks. Other common engineering controls encompass the use of finger-safe components, circuit protection devices (including ground fault detection) and equipment bonding systems.

CSA Z462:21 recognizes the importance of inspecting and maintaining engineering controls to uphold their effectiveness. Some controls, such as equipment doors, may require removal during plant operations and must be replaced to restore the effectiveness of this mitigation scheme. Others, such as ground fault detection devices, may fail unexpectedly and should be regularly tested by plant personnel. An electrical safety program should include procedures for inspecting and maintaining electrical equipment.

4. Warnings

While warnings do not remove hazards from the workplace, they alert personnel of the existence of dangerous conditions and prompt the application of administrative controls and/or personal protective equipment. Typical warnings include labels, signage, lights and audible alert systems.

5. Administrative controls

Administrative controls are procedures designed to promote safe work practices. Common examples include procedures for working on energized equipment, prohibitions from working while fatigued, distracted or under the influence of drugs or alcohol, limitations on working alone, restrictions on unqualified workers and the implementation of emergency plans and first aid procedures.

Two key administrative controls are the plant’s live work and lockout policies. CSA Z462 requires that electrical equipment is de-energized before a worker enters the limited approach boundary unless de-energization is infeasible or would introduce additional hazards. The standard also mandates firms to create a lockout policy and provide lockout training to their employees at three-year intervals.

The objective of a lockout is to securely isolate a piece of equipment from sources of energy while work is being performed. An energy-isolating device, such as a circuit breaker or disconnect switch (in the case of electrical energy), is operated and an individually-keyed lock is applied to prevent the reenergization of the equipment until it is safe to do so. The equipment is then tested to ensure that the isolation is effective – switching mechanisms can fail and equipment may be energized even when a disconnect is in the “off” position. Additionally, testing may reveal that the equipment is fed from different (or multiple) sources that were not anticipated by the worker. Workers should also be aware of the hazards of stored energy, including energy stored in capacitors, the insulation of high voltage cables, hydraulics, pneumatics, suspended parts, springs and other sources.

An important but often neglected component of an administrative control is the documentation of a plant’s electrical systems. Accurate documentation will help workers identify sources of energy and devices that can be used to isolate equipment. However, workers should not assume that the plant’s documentation is accurate. Industrial plants are dynamic workplaces and documentation becomes outdated quickly if not maintained.

6. Personal protective equipment

PPE refers to items worn by personnel to protect them from workplace hazards. As the least effective control method, PPE should be considered a last line of defense when other controls are infeasible or inadequate.

However, PPE is often used in conjunction with other controls as part of an effective hazard mitigation program. PPE must be chosen based on an analysis of the hazards involved. Typical PPE for an electrical worker may include safety goggles, hard hats, hearing protection, insulating gloves and arc flash-rated clothing.

Six categories of hazard control strategies can be implemented in a firm’s electrical safety plan. Priority should be given to removing, reducing and guarding workers from a hazard, but warnings, safe work procedures and PPE are often needed to manage residual risk. Standards like CSA Z462:21 and NFPA 70E are based on this hierarchy and provide guidance for developing a robust electrical safety program.

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