A Comprehensive Guide to Arc Flash Studies (Everything You Need to Know)
Learn the basics of arc flash in 5 minutes or less.
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Table of Contents
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What does an arc flash look like?
Is an arc flash study required by law?
Who is responsible for an arc flash study?
When should I do an arc flash study?
How long does an arc flash study take?
How much do arc flash studies cost?
What's included in an arc flash study?
What are the steps in an arc flash analysis?
FAQs
Why choose Herzig Engineering for your arc flash study?
What is an Arc Flash?
An arc flash is when fault or short circuit in an electrical system creates an electric explosion, releasing intense heat, light, and pressure waves.
The rapid release of energy can cause severe injury to people and equipment, costing companies millions of dollars.
An arc flash can cause major problems:
Damaged equipment
OSHA fines & litigations
Expensive worker comp claims
Long production down times
Worker injuries & fatalities
What does an arc flash look like?
What Causes an Arc Flash
An arc flash happens when electrical current jumps across a gap in an energized system and ionizes the air into a conductive plasma. Most incidents trace back to a handful of preventable conditions rather than freak accidents.
Human Error
Dropped tools, accidental contact, or working on equipment that was not fully de-energized.
Dust & impurities
Conductive dust or debris inside gear that bridges a gap and triggers a fault.
Corrosion & wear
Aged breakers, loose connections, and corroded terminals that lower resistance.
Condensation & moisture
Water intrusion or humidity inside enclosures that creates a conductive path.
Faulty installation
Improper spacing, wrong components, or poor workmanship in the original build.
Equipment failure
Insulation breakdown or a failed component under normal operating stress.
An arc flash study identifies where these hazards are most likely to occur so you can address them before an incident happens.
How to Prevent an Arc Flash
You cannot eliminate electrical energy from a facility, but you can dramatically lower both the odds of an arc flash and the damage one would cause. The most effective steps work together as a program, not in isolation.
1
De-energize before work. Follow lockout/tagout procedures so employees work on de-energized equipment whenever possible.
2
Keep a current arc flash study and labels. Up-to-date incident energy data and warning labels tell workers the real hazard at each piece of gear.
3
Maintain equipment. Clean, inspect, and service electrical equipment on schedule to catch corrosion, dust, and loose connections early.
4
Use the correct PPE. Match personal protective equipment to the incident energy at each location, per NFPA 70E.
5
Follow NFPA 70E work practices. Establish documented safety procedures and train every employee who works on or near energized equipment.
6
Reduce clearing time. Where possible, engineering upgrades such as current-limiting devices or relay settings lower the energy released during a fault.
What is an Arc Flash Study?
An arc flash study (i.e. arc flash hazard analysis) is an analysis conducted by a professional Electrical Engineer to determine the amount of heat energy associated with an electrical arc flash event in a facility's power system. It is a component of an arc flash risk assessment.
The study's mission is to identify the available heat energy, provide mitigation recommendations to lower available energy where possible, and provide needed information to select proper PPE to lower the risks if an arc flash event occurs.
Benefits of an arc flash study:
Identify your facility's current electrical hazards
Apply arc flash safety labels equipment
Identify what your electrical system looks like
Stay 100% within NFPA 70E & OSHA compliance
Identifies the condition and rating of electrical equipment
Is an Arc Flash Study Required by Law?
OSHA mandates employers identify the electrical hazards employees are exposed too. Arc flash is a known electrical hazard. An arc flash study identifies the potential hazard so employees can select the appropriate PPE to work safely around electrical hazards.
The NFPA 70E does mention arc flash by name. This standard, created by the request of OSHA, has outlined guidelines for electrical safety in the workplace, which includes specific standards for arc flash risk assessments.
OSHA & NFPA 70E Codes & Standards
Listed a below are the top three codes and standards related to arc flash
"An arc flash risk assessment shall be performed to identify arc flash hazards, estimate the likelihood of occurrence, and to determine protective measures, including the use of PPE."
NFPA 70E, ARTICLE 130.5
"The employer shall establish, document, and implement (electrical) safety-related work practices and procedures..."
NFPA 70E, ARTICLE 105.3 (A)(2)
"One of the following methods shall be used for the selection of arc flash PPE: (1) the incident energy analysis method or (2)the arc flash PPE category method.."
NFPA 70E, ARTICLE 130.5 (F)
NFPA 70E Standard
OSHA Codes
"Employees working in areas where there are potential electrical hazards shall use electrical protective equipment appropriate for the specific parts of the body for the work being performed."
“The employer shall assess the workplace to determine if hazards are present...”
1910 Subpart 1, 1910.132(d)(1)
"Safety-related work practices shall be employed to prevent electric shock or other injuries resulting from either direct or indirect electrical contacts, when work is performed near or on equipment or circuits which are or may be energized."
CFR 1910.333
Employer vs. Landlord
Who is Responsible for an Arc Flash Study?
Responsibility for an arc flash study is one of the most common points of confusion, especially in leased facilities. In short, the employer who directs employees to work on or near the electrical equipment carries the obligation to identify the hazard, not the property owner. While a landlord may be responsible for the overall safety of common-area electrical systems, the specific arc flash hazard assessment and the safety measures that follow fall on the employer. If a worker injury occurs, however, both parties can be held liable for fines and litigation.
Vs.
Employer
Landlord
Categories | "Employer" | "Landlord" |
|---|---|---|
Fine Potential (if worker injury occurs) | Liable | Liable |
Codes | 1910 Subpart 1, 1910.132(d)(1) , 29 CFR 1910.132 (d)(1), 29 CFR 1910.333 (b)(2)(iv)(B) , 29 CFR 1910.335 (a)(1)(i), 29 CFR 1910.335 (a)(1)(iv) | Liable |
Mentions | 15+ | 0 |
When Should I Do an Arc Flash Study?
The NFPA 70E is clear when discussing the frequency of when a facility should complete an arc flash risk assessment.
An arc flash study should be reviewed or updated at a minimum of every five years, or whenever facility modifications occur. These can be minor changes like fuse type or breaker settings or major changes like power additions or new equipment structure.
Section 130.5 - NFPA 70E
The Typical timeline
How Long Does an Arc Flash Study Take?
From data collection to deliverables in hand, an arc flash study realistically takes 9 to 16 weeks for a facility of 150,000–300,000 sq ft. If the density of electrical equipment is high and add-ons are included (equipment evaluations, coordination studies, and so on), the process will take longer.
Take our example facility: 300,000 sq ft, medium equipment density, five utility transformers, equipment about five years old, and a moderately clean site. With a basic incident energy analysis, arc flash labels printed and applied, and one-line diagrams created, that is an average workload that takes roughly 12 weeks from kickoff to final deliverables.
Example arc flash timeline
A Price Breakdown
How Much Do Arc Flash Studies Cost?
Arc flash studies can cost anywhere between $12,000 and $86,000 per facility. The price depends on a variety of factors, including facility size, density of electrical equipment, age of the equipment, number of utility transformers, arc flash deliverables (equipment evaluation, coordination study, etc.), and more.
Let's take the same 300,000 sq ft facility with medium equipment density and five utility transformers example. The age of the equipment is five years old, and the facility's condition is moderately clean. The facility manager wants a basic incident energy analysis done, arc flash labels printed and applied, and one-line diagrams created. The estimated cost for a facility like this would be $44,171.00.
$12,000 - $86,000
Estimated arc flash study cost
The Arc Flash Deliverables
What's Included in an Arc Flash Study?
A typical arc flash study will include reports and printouts that provide crucial information and analysis regarding the electrical system's potential arc flash hazards.
Here is the list of deliverables commonly found within an arc flash study: single-line diagrams, arc flash labels, a hazard analysis report, a mitigation study, a utility data report, and a fault contribution study. An equipment evaluation and coordination study are add-ons to the study option based on the facility.
Printouts
✔️ Herzig Arc Flash Labels
✔️ Single-line Diagrams
Reports
✔️ Mitigation Study
✔️ Fault Contribution Study
✔️ Utility Data Report
✔️ Arc Flash Hazard Report
The Process
What are the Steps in an Arc Flash Analysis?
The typical arc flash analysis process is fairly simple and can be completed in five steps:
-
Data Collection: The gathering of relevant information about the electrical system and equipment.
-
Engineering Analysis: The use of specialized arc flash software and engineering to calculate arc flash hazards.
-
Labeling: Application of appropriate warning labels on electrical equipment indicating arc flash hazards.
-
Updates: The renewal of an arc flash study, no more than every 5 years.
Conduct periodic
updates
Collect data onsite at your facility
Our engineers calculate your electrical hazards
We build reports, apply tags, labels, and conduct training
Arc Flash Boundary and Incident Energy Explained
Two terms show up on every arc flash label, and understanding them is the key to reading your study results.
Incident energy
Incident energy is the amount of thermal energy a worker could be exposed to during an arc flash, measured in calories per square centimeter (cal/cm²) at a defined working distance (usually 18 inches). The higher the number, the more protective the PPE has to be.
Arc flash boundary
The arc flash boundary is the distance from the equipment at which the incident energy drops to 1.2 cal/cm², the level at which an unprotected worker would receive a second-degree burn. Anyone crossing that boundary must wear arc-rated PPE appropriate to the incident energy inside it.
How to Read an Arc Flash Label
Every piece of equipment covered by your study gets a warning label. Once you know what each field means, the label tells a worker everything they need to work safely.
Nominal system voltage
The operating voltage of the equipment.
Incident energy & working distance
The cal/cm² value at the stated distance (typically 18 in).
Shock protection boundaries
Limited and restricted approach distances for shock hazards.
Arc flash boundary
How far back the second-degree-burn threshold extends.
Required PPE
The arc rating or PPE category needed to work inside the boundary.
Equipment ID & date
Which piece of gear the label applies to and when it was assessed.
Frequently Asked Questions
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