All You Need to Know About Arc Flash


Your Guide to the Best Arc Flash Protection

Simply put, an arc flash is a phenomenon where a flashover of electric current leaves its intended path and travels through the air from one conductor to another, or to ground. The results are often violent and when a human is in close proximity to the arc flash, serious injury and even death can occur.

What is Arc PPE?

Arc flash PPE is arc rated personal protective equipment worn by workers performing maintenance on energized equipment as well as de-energizing equipment and is the last line of defense to protect workers from arc flash injuries

What Does Arc Blast Mean?

An arc blast is the name given to the explosive burst of energy that occurs during an arc flash. An arc blast occurs as the result of a malfunction in the insulation between two energized phase conductors on high powered electrical equipment. Rather than flowing through a conductor, the current flows through the air, which releases thermal energy into the immediate environment.

Arc flash occurs by many things including:

  • Dust
  • Dropping tools
  • Accidental touching
  • Condensation
  • Material failure
  • Corrosion
  • Faulty Installation

Three factors determine the severity of an arc flash injury:

  • Proximity of the worker to the hazard
  • Temperature
  • Time for circuit to break

Because of the violent nature of an arc flash hazard when an employee is injured, the injury is serious – even resulting in death. It’s not uncommon for an injured employee to never regain their past quality of life. Extended medical care is often required.

Typical Results from Arc faults

  • Burns (Non FR clothing can burn onto skin)
  • Fire (could spread rapidly through building)
  • Flying objects (often molten metal)
  • Blast pressure (upwards of 2,000 lbs. / sq.ft)
  • Sound Blast (noise can reach 140 dB – loud as a gun)
  • Heat (upwards of 35,000 degrees F)

Approach / Protection Boundaries

The National Fire Protection Association (NFPA) has developed specific approach boundaries designed to protect employees while working on or near energized equipment.

These boundaries are:

Flash Protection Boundary (outer boundary)

An arc flash boundary is the farthest established boundary from the energy source. If an arc flash occurred, this boundary is where an employee would be exposed to a curable second degree burn (1.2 calories/cm2 ). The issue here is the heat generated from a flash that results in burns.

Limited Approach Boundary

An approach limit boundary is the distance from an exposed live part where a shock hazard may exist.

Restricted Approach Boundary

An approach limit boundary is the distance from an exposed live part where a shock hazard is immanent.

Prohibited Approach (inner boundary)

A distance from an exposed part which is considered the same as making contact with the live part. This distance is not common between equipment. Some equipment will have a greater flash protection boundary while other equipment will have a lesser boundary.

Ways to Protect the Workers

There exists a number of ways to protect workers from the threat of electrical hazards. Some of the methods are for the protection of qualified employees doing work on electrical circuit and other methods are geared towards non-qualified employees who work nearby energized equipment.

Here are a few of the protective methods:

De-energize the circuit

Work Practices




Ground Fault Circuit Interrupters (GFCI)

Grounding (secondary protection)

If You Must Work on Energized Circuits If it has been determined that deenergizing a circuit is not feasible and the employee must work “hot”, the employer shall develop and enforce safety-related work practices to prevent electric shock or other injuries resulting from either direct or indirect electrical contacts. The specific safety-related work practices shall be consistent with the nature and extent of the associated electrical hazards.

These safety related work practices could include:

Energized Electrical Work Permit

Personal Protective Equipment

Insulated Tools

Written Safety Program

Job Briefing

Fast Fact: The most effective and fool-proof way to eliminate the risk of electrical shock or arc flash is to simply deenergize the equipment.

Understanding the Arc Flash Warning Labels

Each piece of equipment operating at 50 volts or more and not put into a deenergized state must be evaluated for arc flash and shock protection. This evaluation will determine the actual boundaries (i.e. prohibited, limited, restricted etc) and will inform the employee of what PPE must be worn. Once the evaluation is complete an Arc Flash Hazard warning label must be affixed to the equipment and readily accessible to employees who may work on the energized equipment.

The Employees Obligation Employees must follow the requirements of the Arc Flash Hazard label by wearing the proper personal protective equipment (PPE), use of insulated tools and other safety related precautions. This includes not working on or near the circuit unless you are a “qualified” worker.

Who's Qualified to work near the circuits?

A qualified person who has received training in and has demonstrated skills and knowledge in the construction and operation of electric equipment and installations and the hazards involved.

Additional requirements for qualified persons.

Qualified persons (i.e. those permitted to work on or near exposed energized parts) shall, at a minimum, be trained in and familiar with the following:

  • The skills and techniques are necessary to distinguish exposed live parts from other parts of electric equipment.
  • The skills and techniques necessary to determine the nominal voltage of exposed live parts.
  • The clearance distances specified in 1910.333(c) and the corresponding voltages to which the qualified person will be exposed.

Some of the commonly used arc rated clothing items -

Find more Arc Rated PPE at Enviro Safety Products!

Frequently Asked Questions About Arc Flash

What PPE is used for arc flash?

PPE - safety glasses or safety goggles, hearing protection (ear canal inserts), voltage rated gloves with leather protectors. Clothing - Arc-rated long-sleeve shirt and pants or arc-rated coverall, arc-rated face shield or arc flash suit hood, arc- rated jacket, parka, rainwear, or arc-rated hard hat liner.

Face protection includes face shield and/or safety glasses. Hand protection includes leather over rubber for arc flash protection. Leather work boots above 4 cal/cm².

Arc Flash PPE A comprehensive line of PPE designed to protect your workers against arc flash hazards. Face shields, protective coats, hard hats and more. Protect Workers Against a Flash

Take the proper steps to ensure your safety before taking any measurements, especially on energized equipment. Know where the arc flash boundaries are and keep these top safety measures in mind. The National Fire Protection Association ( NFPA ) recommends defining three boundaries to minimize risk of electrical injuries.

Why is arc flash so harmful?

During an estimated 10 arc flashes per hour in the United States, the NIOSH reports arc flashes can produce the greatest temperature known on the earth up to 35,500 degrees.

Who determines arc flash boundaries?

Limitations and restrictions on approaches dealing with shocks are determined in accordance with Table 1300.4c). A) a power supply and (130.4 C). (b) For DC systems where arc Flash borders have been determined through an Arc Flash Analysis or through the use of Arc Flash Category PP. (b)

What are the OSHA guidelines for arc flash safety?

The arc-flash hazards of personnel and equipment are included in 1910.135(a)(1)(v), "Safeguards for personnel protection." The requirement consists for the wearing of protective equipment (PPE) for the eyes and faces in situations where there is potential for injury.

How do you choose arc flash PPE?

The incident intensity must be measured at ca/cm2. Typically the maximum power produced with the equipment during flash events cannot exceed the calculated cal/cm2. Your arc flash PPE must include a mark with an arc thermal protective value rating of ATP.

Is arc flash an electrical hazard?

Electrical shocks and burn hazards in the workplace can cause a fire or electrical explosion. Blasts. Ark flash.

Can you get shocked from arc flash?

The risks of the shock or an arc Flash Electrical power moves in an area that causes shock. While the risks associated with arc flash versus electrical explosion occur in both cases, there is an enormous variation in fatalities in the cases.

What is the top most common caused of arc flash hazards?

Human errors are most commonly caused by arc flash. Once a worker has completed the same task without incident, they can bypass the maintenance step.

When should you use arc flash safety protection?

Employees are required to wear arc rated safety equipment and arc flash protection when they experience electrical shock or flashing.

Which level of arc flash personal protective equipment is the most protective?

PPE class 4 is currently the highest standard in conformity with the rating for arcs exceeding 40cal/m2. These categories require additional layers and typically include: AR flash suits and jackets or AR coversalls. An arc rating must be 40 kg /cm.

How do you protect someone from arc flash?

The special protective eyewear is needed for protection against arc flash. They must be non-conductive and dielectric so no exposed metal parts can be exposed.