Arc Flash Risk Assessment for Reducing Risk

By R.W. Hurst, Editor

Arc flash risk assessment is a critical process used to identify electrical hazards, evaluate incident energy levels, and establish safe working boundaries. By analyzing fault current, arc duration, and equipment conditions, facilities can reduce exposure to high-energy events and ensure compliance with NFPA 70E and OSHA regulations. This essential safety practice supports hazard mitigation, PPE selection, and overall electrical risk management.

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What Is Involved in an Arc Flash Risk Assessment?

The arc flash risk assessment process is a comprehensive approach to identifying, analyzing, and mitigating electrical hazard exposure levels. It’s more than a safety audit—it’s a technical study that quantifies risks and recommends solutions.

Key steps include:

Data Collection
- Review system one-line diagrams and gather electrical nameplate information.
- Perform field verification to confirm accuracy of drawings and component ratings.
- Collect details on grounding, transformer configuration, and conductor lengths.
Short Circuit and Coordination Study
- Conduct a short circuit energy analysis to identify available fault current at each node.
- Evaluate time-current coordination to ensure upstream devices operate before downstream ones.
Incident Energy Analysis
- Use IEEE 1584 formulas to calculate incident energy release at various equipment points.
- Factor in working distance, equipment enclosure type, and arc duration to determine exposure values.
Hazard Identification and Boundary Setting
- Establish shock protection boundaries and arc flash boundaries based on calculated energy levels.
- Define the approach limits and restricted zones for qualified personnel.

PPE Selection Based on Risk Levels

Once the energy levels are determined, proper Personal Protective Equipment (PPE) must be selected. This ensures that workers are protected based on the severity of the arc flash risk, expressed in calories per square centimeter (cal/cm²).

PPE categories are defined as follows:

Category 1 (up to 4 cal/cm²) – FR shirt and pants, face shield with balaclava
Category 2 (4.1–8 cal/cm²) – Category 1 PPE plus arc-rated coveralls or suit
Category 3 (8.1–25 cal/cm²) – Additional arc-rated layers, gloves, hard hat with hood
Category 4 (25.1–40+ cal/cm²) – Heavy-duty arc suit with flash hood, balaclava, and gloves

To explore further, review the arc flash study requirements that support proper PPE classification.

Standards That Govern Arc Flash Risk Assessment

Arc flash hazard evaluations must adhere to established codes and methodologies. The two most recognized standards—NFPA 70E and IEEE 1584—guide risk identification, calculation, and control measures.

Compliance considerations include:

NFPA 70E – Defines safe work practices, PPE requirements, labeling protocols, and training expectations.
IEEE 1584 – Provides mathematical models for incident energy analysis based on real-world test data.
OSHA 29 CFR 1910.333 and 1910.269 – Mandate electrical hazard awareness and control as part of a broader safety program.

If you're concerned about your site's compliance with national regulations, see our guide to incident energy as a core element of electrical risk evaluation.

Labeling and System Documentation

Arc flash studies culminate in updated equipment labels, hazard documentation, and maintenance schedules. Labeling ensures that every worker understands the energy risk and PPE required before starting any energized task.

Required documentation includes:

Equipment-specific arc flash labels indicating voltage, incident energy, boundaries, and required PPE.
A formal engineering report detailing methods, assumptions, and recommendations.
A reassessment schedule, typically every five years or after major system modifications.

Explore how these elements are calculated in our incident energy analysis page, which outlines key factors that affect energy release.

Worker Safety Training and Risk Awareness

Arc flash awareness doesn’t stop at engineering—it must be reinforced through electrical safety training. Workers must understand the nature of the hazard and how to respond effectively in high-risk environments.