Arc Flash


Electrical Safety Services



Arc Flash-Related Federal Agencies & Industry Associations

Arc Flash

What is an arc flash?

An arc flash is the flow of current traveling through the air. It causes the release of potentially large amounts of energy into the air resulting in an explosion up to 35,000 degrees in an instant.

What causes an arc flash?

An arc flash is caused by a phase-to-phase or phase-to-ground fault. This can happen for many reasons including rusting equipment, improper work procedures or even a spider web that becomes humid and moist.

What factors determine the brightness, temperature and intensity of an arc flash?

The overall strength of an arc flash is dependent on the following variables:

  • The amount and duration of power applied to the electrodes
  • The distance between the electrodes
  • The type of gas located in the gap between the electrodes
  • The amount of pressure of the gas

What can happen to a worker in an arc flash?

Due to the hazards that can be present in an arc flash, a worker can suffer first, second, and/or third degree burns beginning at the upper portion of the body and not only on the front but also on the back, internal damage to vital organs from high amounts of voltage traveling through the body, blunt force trauma from the blast, shrapnel causing additional damage to the skin, vision damage both directly after the incident and also as time passes, health effects from breathing toxic fumes, and hearing loss.

My facility uses low voltages, should I still be worried about an arc flash occurring?

It depends on what you consider low voltage but as long as you have 3 phase 208 volts coming into the facility, you should be concerned of the potential hazards of an arc flash. Even with a minimum of 208 volts, the PPE Category could be anywhere between 1 and dangerous. That's why it's important to have an assessment performed to understand the hazards.

What does an arc flash incident cost?

There are many associated costs with plenty of variables. It would depend on how much it would cost in downtime, fines assessed by OSHA, electrical equipment repair or replacement, medical bills, workers compensation, litigation, increased insurance premiums, and the void in expertise and decreased morale can be invaluable.

What can be done to reduce the risk?

Once a study performed by a competent professional is completed, specific mitigation recommendations can be provided.

How often do arc flash incidents happen?

Between 1992 and 2002, over 2,000 workers a year were injured by an arc flash. This does not include the arc flashes where no one is injured which is thought to be more common.

What's the difference between a 1st, 2nd &amp 3rd degree burn?

  • 1st degree – Only the top layer is affected and includes pain, redness and minor swelling
  • 2nd degree – Blisters are appear along with redness and severe pain.
  • 3rd degree – This most serious type of burn where all the layers of skin are affected as well as the underlying tissue. The skin looks dry and can appear brown, charred, white or waxy. Initially, pain may be little or none because of nerve damage.

What's the difference between an electrical shock and electrocution?

Essentially, the difference is life and death. Electrical shock is when voltage goes through part or all of a worker's body and lives. Electrocution is where voltage goes through the body and the worker doesn't live.


What is an arc flash label?

An arc flash label is a label placed on applicable electrical equipment after an arc flash assessment is complete warning trained workers of the hazards present and the personal protective equipment necessary to mitigate the risk.

Why does my electrical equipment need labeling?

If an electrical panel is clearly marked, anyone who is properly trained will know the hazards and what they need to wear to mitigate those.

Electrical Safety Services

What are the benefits of having an arc flash assessment done?

The following are some of the benefits for conducting an assessment.

  • Increased employee safety
  • Recommends most appropriate level of protection
  • Insurance premiums can be reduced
  • Reduced electricity bill
  • Increased system reliability
  • Enhanced safety culture
  • Software used makes updates and changes less expensive and tedious
  • Under- or over-utilized equipment is identified
  • Increased morale
  • Aids in future plans for expansion

What are the costs of not having an arc flash assessment done?

The following are some of the costs for avoiding an assessment:

  • OSHA fines due to non-compliance
  • Increased downtime and lost productivity
  • Increased equipment replacement & maintenance costs
  • Medical expenses for injured workers
  • Legal costs

Why do I need an arc flash assessment?

It's the responsible thing to do. Most companies want to keep their workers safe and prevent a potentially catastrophic event from occurring. It helps to keep your business running. An arc flash can have a serious affect on your profit / loss statement. Yes, OSHA requires employers to protect workers from hazards as stated in the General Duty Clause but that's the last reason you should consider.

How often do I need to have an arc flash assessment done?

Per NFPA 70E 2015, every 5 years or when major changes are made to your electrical system.

Can I perform the assessment myself?

Yes, you can conduct an arc flash assessment but it may take you longer than you expect, take you away from other work, there might be errors due to issues you may not have considered. You can also obtain free software that will help you do your own assessment but usually the old adage is true: you get what you pay for. Salisbury by Honeywell's recommendation is to have a professional assist you, even if it's someone else.

Can the tables found in NFPA 130.7 (C) (9) be used in the place of an arc flash assessment?

They can be used under electrical engineering supervision. Use under any other situation is simply not protecting you or your workers.

How much does an arc flash assessment cost?

Assuming a point is a bus or protective device that will require an arc flash label, the cost of an assessment varies from $100-$200 per point depending on the following variables:

  • Size of facility
  • Density of the equipment connected to the distribution system
  • Quality of the drawings available for review and use
  • Complexity of the system
  • Quality and quantity of the clients involvement in the process
  • On-site generation (independent or parallel with the utility)
  • How far downstream from the utility the client wishes to go
  • Quantity of motors (ANSI spec motors greater than 50HP must be modeled individually. We go to 25HP)

Why are arc flash assessments required now if the hazards have been around a long time?

Understanding in this field is maturing where awareness, acceptance and compliance has been lagging. For this reason, OSHA has begun to apply stricter enforcement.

What's my role in the assessment?

You can provide the most up-to-date single-line diagram you have, an electrical floor plan and site drawings, original equipment shop drawings, trip setting records or previous professional studies. Accurate documents will speed up the process and potentially lower the cost of the assessment. The most important of these is the single-line diagram. Some already have this prepared, others prefer to do this on their own but for others, it's not an option.

Can an arc flash be prevented?

Arc flashes can't be prevented any more than car accidents. Best practice procedures can be followed (e.g. driving defensively) to try and prevent an incident but arc flashes can not be prevented. Certain things can be done, however, to mitigate the results (e.g. wearing your seat belt) in the event an incident were to occur.

OSHA doesn't say an arc flash assessment is a requirement, why do I still need to have one done?

While an arc flash assessment isn't specifically mentioned in any OSHA regulation, the General Duty Clause makes an assessment necessary because the presence of a clear hazard to workers exists.

How long will an arc flash assessment take?

From start to finish, an assessment usually takes anywhere from a week to a few months depending on the amount of work needed to be performed. As far as physically being at your facility, it is usually between a couple of hours to a few weeks.

What should be expected upon completion of an arc flash assessment?

At the completion of an assessment, you should be provided an updated single-line diagram that assesses every device down to the floor level, new warning labels on all applicable equipment and a report that summarizes the findings and provides recommendations on how to reduce the hazards.

What's needed to be compliant in reference to my electrical system?

To be OSHA compliant, the following is needed

  1. A facility must provide, and be able to demonstrate, a safety program with defined responsibilities.
  2. Calculations for the degree of arc flash hazard.
  3. Correct PPE for workers.
  4. Training for workers on the hazards of arc flash.
  5. Appropriate tools for safe working.
  6. – Warning labels on equipment are field marked with nominal voltage and the arc flash boundary., They must also have at least one of the following: Incident energy as well as working distance or arc flash PPE category.

What are the steps of an arc flash assessment?

The steps that go into an assessment are as follows:

  1. Collect electrical system data
  2. Determine modes of operation
  3. Determine bolted fault currents
  4. Determine arc fault currents
  5. Determine protective device characteristics and duration of arcs
  6. Document voltages and equipment classes
  7. Establish working distances
  8. Determine incident energies
  9. Determine Flash Protection Boundary (FPB)


What can happen if I don't provide PPE to the workers I'm responsible for?

This answer depends on the type of organization affected. A corporation can be fined by OSHA. As owner of a private establishment, the owner can be held personally liable.

Can I just provide my workers with PPE Category 4 protection and skip the arc flash assessment?

You can but you might not want to go with that option. The suits with the highest level of protection may not be enough to protect your workers, they may not be necessary, they can be very hot to work in depending on the season, recommendations can be made to reduce the hazards, you won't know if additional equipment is necessary.

How is the appropriate PPE determined?

By determining the ATPV which comes after an arc flash assessment.

If I'm wearing the proper PPE for the identified hazard, I'm good right?

Even with the proper PPE, a worker has a 50% chance of getting a 2nd degree burn. That's just what the standards require. Essentially, recovery and returning to work is a possibility.

Apart from what workers wear, what equipment should be purchased?

It depends on the voltage but whatever it is, Salisbury by Honeywell will most likely have it.

Who needs Electrical PPE?

Employees working within the Restricted Approach Boundary must wear Electrical PPE.

What does Electrical PPE not protect from?

In respect to electrical safety, Salisbury by Honeywell's PPE doesn't protect against such hazards as shrapnel, blast pressure, falls or specific vision issues, as a result of an arc flash. It does help mitigate the effects of an arc flash.


Why do I need to provide training?

It's not enough to give your workers PPE, they must be trained on the recognizing the hazards, how to use and maintain the PPE, how to avoid electrical incidents as well as proper procedures.

Who needs to be trained and how often does it need to happen?

Workers exposed to shock hazards and those responsible for taking action in case of an emergency. An employee should be re-trained at least every 3 years or under any of the following conditions:

  • Supervision or annual inspections identify a worker is not complying with the safety-related work practices.
  • If new technology, new equipment, or changes in procedures require a change in safety-related work practices.
  • A worker needs to use safety-related work practices outside the regular duties

Arc Flash-Related Federal Agencies & Industry Associations

I'm confused about all the standards, associations, societies and federal agencies. How does it come together?

Who created OSHA and when?

Congress voted on the Occupational Safety Health Act that would create OSHA and it was passed into law by Pres. Nixon in 1970.

What are OSHA's priorities when performing an inspection?

Here are some of OSHA's top priorities for inspections:

  1. Reports of imminent dangers or accidents
  2. Fatalities or accidents where 3 or more workers are sent to the hospital
  3. Employee complaints
  4. Referrals from other government agencies
  5. Targeted inspections like the Site Specific Targeting Program which focuses on employers who have a high injury or illness rates.
  6. Follow-up inspections

Where do I go to find information about an OSHA inspection?

Anyone interested in OSHA inspections can go to their website (www.osha.gov).

How can OSHA inspections be challenged or appealed?

To dispute results of an OSHA inspection, a notice of contest must be filed within 15 business days to the Occupational Safety and Health Commission.

Who needs to keep records of work-related injuries or illnesses?

Any employer with 11 or more workers must keep these types of records. Low-hazard industries like retail, real estate, finance and other services are except from this requirement.