Arc Flash Training

In our NFPA 70E Training, we provide a detailed examination of arc flash hazards, ensuring that participants fully understand the risks and the necessary precautions to take when working with or around electrical systems.  Here is what we cover.

Understanding Arc Flash and Arc Blast

• Participants learn that an arc flash is the intense light and heat generated during an electrical fault, while the arc blast is the resulting pressure wave.

The Four Variables

We dive into the four variables that make arc flash so dangerous:

1. Heat:  We discuss how temperatures in an arc flash can reach between 5,000 and 35,000 °F  and the potential severe burns, ignition of clothing, and melting of metals.
2. Light:  The training covers the intense light produced during an arc flash and its potential to cause eye injuries and ignite nearby materials.
3. Sound:  We address the powerful acoustic wave generated by the arc blast, which can lead to hearing damage and contribute to the overall danger.
4. Pressure:  Participants learn about the force of the pressure wave from an arc blast, capable of throwing workers, rupturing panels, and turning debris into projectiles.

Common Causes of Arc Flash

• The training includes a thorough review of what can trigger an arc flash, such as voltage transients, accidental contact with live components, or improper work practices.  We emphasize the unpredictability and severity of these incidents, which can release immense energy in just microseconds.

Impact and Potential Injuries

• We cover the types of injuries and damage that can result from arc flash incidents, including severe burns, hearing loss, and injuries from flying debris. The training underscores the importance of being prepared for these risks.

In our NFPA 70E training, we cover the requirements for Personal Protective Equipment (PPE) as required by OSHA and NFPA 70E.  Understanding the connection between OSHA’s regulations and NFPA 70E’s guidelines is essential for both compliance and safety in environments where electrical hazards are present.

OSHA PPE Requirements

OSHA sets the foundational requirements for electrical safety, emphasizing what must be done to protect workers:

• Personal Protective Equipment (PPE) Mandates (1910.335):  OSHA requires that employees exposed to potential electrical hazards must be provided with, and must use, appropriate PPE for the specific risks and the parts of the body that need protection.
• Maintenance and Inspection:  PPE must be kept in a safe, reliable condition and inspected regularly, as specified by OSHA standards.
• Head, Eye, and Face Protection:  Nonconductive head protection is required where there’s a danger of electric shock or burns. Additionally, eye and face protection must be used when there’s a risk of injury from electric arcs, flashes, or flying objects.
• Insulated Tools and Equipment:  Insulated tools and equipment are required when working near exposed energized conductors to prevent accidental contact.

NFPA 70E PPE Guidelines

While OSHA outlines the “shall,” NFPA 70E provides the “how”—detailing the implementation of protective measures:

• General PPE Requirements (130.7): NFPA 70E specifies that employees must use protective equipment designed for the specific electrical hazard and the part of the body at risk. Arc Flash PPE must be worn when working within the arc flash boundary.
• Care and Maintenance: NFPA 70E explains how to maintain PPE in a safe, clean, and reliable condition. The requirements for PPE being inspected before each use.

Specific PPE Requirements

• Head, Face, Neck, and Chin Protection: Nonconductive headgear and face protection must be worn whenever there’s a danger from electric shock or arc flash. This includes arc-rated hoods and face shields when working within the arc flash boundary.
• Eye Protection: Protective eyewear is required under face shields or hoods, ensuring that eyes are protected from arc flash and flying debris.
• Body Protection: Arc-rated clothing is essential when there’s a risk of exposure to arc flash above certain energy levels. This clothing must cover all parts of the body and be properly fitted to allow movement without compromising protection.
• Hand and Arm Protection: Rubber insulating gloves with protectors are required for electric shock protection, with additional guidelines for arc flash protection.
• Foot Protection: Insulated or dielectric footwear is necessary when working in areas where there’s a risk of electric shock or arc flash.

Identify Arc Flash Hazards

The first step in an arc flash risk assessment is to identify the presence of arc flash hazards in your work environment. This involves a thorough examination of electrical equipment and systems to determine where and how an arc flash could occur.

Estimate Likelihood and Severity

Next, the assessment must estimate both the likelihood of an arc flash event occurring and the potential severity of injury or damage to health. This estimate takes into account the design and condition of the electrical equipment, including the operating condition and the maintenance state of overcurrent protective devices.

Determine Protective Measures

Based on the likelihood and severity of potential arc flash events, additional protective measures may be required. These measures, selected according to the hierarchy of risk control, could include the implementation of specific safety-related work practices, establishing arc flash boundaries, and determining the appropriate PPE to be used within those boundaries.

Documentation

The results of the arc flash risk assessment must be documented. This documentation provides a record of the identified hazards, the analysis performed, and the protective measures implemented, ensuring compliance with safety standards and providing a reference for future assessments.

Establish Arc Flash Boundaries

The arc flash boundary is a critical concept defined as the distance at which the incident energy equals 1.2 cal/cm² (5 J/cm²). This boundary helps to determine the areas where specific protective measures and PPE are necessary to protect workers from the thermal effects of an arc flash.

Select Arc Flash PPE

Selecting the appropriate PPE for workers operating within the arc flash boundary is essential. Two methods are available for this selection: the incident energy analysis method and the arc flash PPE category method. The chosen method will guide the selection of arc-rated clothing and other protective gear based on the potential energy exposure during specific tasks.

Equipment Labeling

Finally, electrical equipment that is likely to require examination or maintenance while energized must be properly labeled. These labels should include critical information such as nominal system voltage, the arc flash boundary, and either the incident energy or the appropriate PPE category. Accurate labeling ensures that all personnel are aware of the potential hazards and the required safety measures.

1. Incident Energy Analysis Method

The Incident Energy Analysis Method is a detailed approach that calculates the incident energy at the working distance (18 inches in most cases).  Incident energy is defined as the amount of thermal energy (expressed in cal/cm²) generated during an electrical arc event.  This method requires an arc flash risk assessment to determine both the incident energy at the working distance and the arc flash boundary.

• How it Works: The arc flash risk assessment calculates the incident energy, which guides the selection of PPE with an arc rating that meets or exceeds this energy level.  The arc flash boundary, defined by this energy, marks the distance within which appropriate PPE must be worn.
• Advantages:  This method is highly accurate and specific to the equipment being assessed, often resulting in customized arc flash labels that simplify PPE selection and compliance. It ensures that the selected PPE matches the actual arc flash potential, providing optimal protection for workers.
• Disadvantages:  The Incident Energy Analysis Method can be costly and time-consuming due to the need for detailed data collection and calculations.  However, its precision and effectiveness make it the superior choice for ensuring safety.

2. Arc Flash PPE Category Method

The Arc Flash PPE Category Method is an alternative approach that uses standardized tables from NFPA 70E to estimate the arc flash risk based on known parameters such as maximum available fault currents, clearing times of overcurrent protective devices, and working distances.  This method is often used when an updated incident energy analysis is not available.

• How it Works:  By referencing NFPA 70E tables, workers make an educated estimate of the arc flash potential and determine the appropriate arc flash PPE category and necessary protective gear.  This method provides a quick solution when specific electrical data is not available, making it a practical choice in certain situations.
• Advantages: The primary advantage of the Arc Flash PPE Category Method is its applicability in situations where an updated incident energy analysis is not available. It allows for the estimation of arc flash risks and the selection of appropriate PPE based on standardized guidelines.
• Disadvantages:  This method is less precise and often requires more PPE than necessary. There’s also a risk that the actual arc flash potential could exceed the PPE rating, potentially leaving workers under protected. Additionally, the PPE Category Method cannot be used if critical parameters, like fault current and clearing times, are unknown or don’t align with NFPA 70E tables.

Inspection Requirements

• Rubber Insulated Gloves:  Before each use, rubber insulated gloves must be inspected for any signs of damage.  This includes performing an air test to check for leaks or punctures and inspecting the leather outer layer for holes or contaminants.  Gloves must undergo periodic electrical testing every six months after first use, and they should be stored in a manner that preserves their integrity.Arc Flash
• Shields and Suits: Arc flash shields should be inspected for cracks, and the fabric surrounding the shield must be checked for holes.  Arc-rated suits should be inspected for damage, including wear, pilling, and holes.  Any compromised gear must be replaced, as repairs may not maintain the original level of protection.

Care and Maintenance Practices

• Storage:  PPE must be stored to avoid damage from environmental factors such as moisture, dust, or physical impacts.  Rubber gloves should not be crammed into storage bags to prevent deformation and loss of structural integrity.  Arc flash suits and other gear should be stored according to manufacturer recommendations.
• Cleaning:  Arc-rated suits and uniforms must be laundered according to manufacturer guidelines.  Contaminated or improperly cleaned gear can lead to catastrophic failure during an arc flash event.  It is crucial to use the correct detergents, wash cycles, and temperatures to preserve the protective qualities of the material.
• Maintenance of Arc-Rated Clothing:  Employees must ensure that their arc-rated clothing is free from holes, rips, and tears.  Such damage must be addressed promptly, but with caution—replacing the garment is often safer than repairing it, as repairs might not restore the original protection level.  Underlayers should be 100% cotton and covered fully by arc-rated material, and care should be taken not to use products like baby powder that can degrade rubber gloves.

Compliance and Responsibility

Employers are responsible for ensuring that PPE is maintained in a condition that guarantees safety. This includes establishing policies and procedures for the inspection, care, and maintenance of protective equipment in their electrical safety program. Both employers and employees must adhere to manufacturer instructions and consensus standards, such as ASTM F1449 and ASTM F2757, to ensure that PPE remains effective throughout its lifespan.

Fit and Proper Use

Arc flash PPE must fit properly to provide the intended protection. It should not be too tight or too loose, as this could compromise the air gap that provides thermal insulation. Employees must also avoid using rubber gloves without the protective leather outer, as this reduces the glove’s protection level by 1 class (example Class 0 to Class 00 or 1000 VAC to 500 VAC max use rating) and necessitates retesting.

Exceeding Minimum Standards for Enhanced Safety

NFPA 70E Article 130.7(C)(6) mandates that employees wear arc-rated clothing wherever there is possible exposure to an electric arc flash above 1.2 cal/cm², as this level can cause a second-degree burn.

However, even when incident energy is below this threshold, it is prudent to consider additional protection.

The arc flash boundary is intended to protect you from second- and third-degree burns, but you can still receive first-degree burns and other injuries outside the boundary if you are not wearing arc-rated PPE.

This is why our recommendations go beyond the minimum requirements.  Simply not wearing a tinted arc-rated faceshield or your hearing protection can have consequences far beyond burns to the skin.  Eye injuries and hearing damage, are real risks, even at lower energy levels.

Hand Protection

• Within the Restricted Approach Boundary for Shock:  Workers should wear rubber insulating gloves with leather protectors to guard against both shock and arc flash hazards.
• Outside the Restricted Approach Boundary for Shock:  Arc-rated nitrile gloves, leather gloves, or rubber insulating gloves with leather protectors should be used to ensure adequate protection against arc flash hazards.

Head and Body Protection

• Helmet, Safety Glasses, and Arc-Rated Face Shield:  Wearing safety glasses alone isn’t always enough. It’s crucial to wear an arc-rated faceshield as well, even for exposures under 1.2 cal/cm².  A relatively “small” arc flash can still produce a flash bright enough to cause eye injuries similar to arc eye.  There have been cases where employees exposed to less than 1.2 cal have suffered eye injuries that caused pain and kept them out of work for several days, even though they experienced no burns.
• Hearing Protection: An arc flash under 1.2 cal/cm² can still be loud enough to cause ear injuries. Employees have experienced hearing damage and balance issues due to the loud noise of an arc flash, leading to missed work from inflammation and fluid buildup in the ear.