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Electrical Protection: Arc Flash Quick Facts

by with No Comment Electrical Safety

Arc flashes are one of the most dangerous electrical hazards in industrial environments. They occur when electrical current passes through the air between ungrounded conductors or between a conductor and the ground. The resulting explosion can cause severe injury or even death. Understanding the extreme conditions generated by an arc flash can help in implementing better safety measures and mitigating these risks.

Here’s a closer look at the key dangers of arc flashes:

  • Temperature: Arc flashes can generate temperatures as high as 35,000°F—four times hotter than the surface of the sun. This intense heat is capable of vaporizing metal and igniting fires, creating life-threatening conditions in the blink of an eye.
  • Speed: Arc flashes happen in less than a second, reaching speeds of up to 700 miles per hour in milliseconds. The rapid expansion of hot gases can lead to devastating effects on nearby individuals and equipment.
  • Pressure: The explosive force of an arc flash creates a pressure wave, commonly referred to as an “arc blast.” This wave can knock a person off balance, send debris flying, and potentially cause concussions or serious internal injuries.
  • Sound: The sound of an arc flash can reach up to 140 dB, comparable to the noise produced by a jet engine or gunshot. Such intense sound levels can cause instant, irreversible hearing damage or rupture eardrums, further endangering those in the vicinity.
  • Light: An arc flash produces an intensely bright light, reaching over 1 million lux just three meters from the source. A recent test recorded 13.1 million lux—130 times brighter than direct sunlight. This extreme light intensity can cause permanent eye damage or blindness if proper eye protection is not used.
  • Prevalence: Arc flashes are common in industries involving high-voltage electrical systems, such as manufacturing, utilities, oil and gas, and construction. In these environments, workers are often exposed to the potential for arc flash incidents, making safety precautions and training essential.

Arc flashes are not just rare occurrences—they are significant and present hazards in many industries. The extreme heat, pressure, sound, and light generated by an arc flash pose substantial risks to workers. Proper training, protective equipment, and safety protocols are crucial in preventing and minimizing the devastating effects of these electrical explosions. Prioritizing safety helps to protect both workers and the integrity of critical electrical systems.

ELECTRICIAN WITH A SPARK

Electrical Protection: Types of Hazards

by with No Comment Electrical Safety

Many industries face significant electrical hazards, including construction, mining, manufacturing, oil and gas, automotive, and electrical work. Understanding the types of electrical hazards and the proper safety measures is crucial to protecting workers from potentially fatal injuries.

Electrical Shock

Electrical shock is one of the most common electrical hazards. It occurs when the human body comes into contact with an electric current. The severity of an electrical shock depends on several factors, including:

  • Amount of current: Higher current typically results in more severe injury.
  • Duration of exposure: Longer contact with electricity increases the risk of damage.
  • Path through the body: The severity varies depending on the path the current takes through the body. For example, a current passing through the heart or brain can be fatal.
  • Frequency: The type of electrical current (AC or DC) and its frequency can also affect the level of harm.

Arc Flash

An arc flash is a type of electrical explosion caused by an arc fault. It generates intense light and heat, with temperatures reaching up to 20,000°C (36,000°F)—hot enough to cause severe burns or even vaporize skin. Arc flashes are incredibly dangerous, as they can occur without warning and spread rapidly.

Arc Blast

An arc blast refers to the pressure wave created by an arc flash. This pressure wave can cause significant damage to the body, including:

  • Serious injuries to internal organs
  • Traumatic brain injuries due to the force of the blast
  • Hearing loss due to the extreme sound pressure levels

Arc blasts can produce sound levels exceeding 140 dB, which is louder than a jet engine and can result in permanent hearing damage.

Sound Blast

The sound generated by an arc blast can exceed 140 decibels—a level that is capable of causing permanent hearing loss. Prolonged exposure to such intense noise levels is highly dangerous.

Arc-Rated vs. Flame-Resistant PPE

It’s important to understand the difference between arc-rated (AR) and flame-resistant (FR) personal protective equipment (PPE).

  • Flame-resistant (FR) PPE is designed to resist ignition and self-extinguish if exposed to flame.
  • Arc-rated (AR) PPE is specifically tested to protect against the high-intensity energy released by an arc flash or arc blast.

While all arc-rated PPE is flame-resistant, not all flame-resistant PPE is arc-rated. Arc-rated gear is subjected to rigorous testing to ensure it can withstand the extreme heat and energy generated by an arc flash, offering a higher level of protection for workers in electrical environments.

Fire Fighter

AR vs FR Clothing

by with No Comment AR/FR

FLAME RESISTANCE

Made from engineered fibers that inherently resist ignition or self extinguish once source of flame is removed and inhibit fire spread. Can be washed as many times as needed, and it does not compromise FR properties. Examples: Dupont Nomex, Dual Hazard and Modacrylic

FIRE RETARDANT

Made from fabrics that are flammable and treated with flame-retardant chemicals that make it flame resistant. Flame resistant materials may also be treated to increase protection. The flame-retardant properties may diminish over time. On the tag, you will see max number of washes before it is no longer flame-retardant. Typically more cost effective. Examples: Westex Indura and Ultrasoft

ARC-RATED

Arc rated clothing measure the insulation of FR fabrics, designed to protect from the intense heat AND energy from arc flashes. Arc ratings determine how much energy the fabric can block before it can cause 2nd degree burns to the wearer. AR clothing is required when employees are near or working on exposed live parts greater than 600v.

All arc-rated clothing are flame resistant, but not all FR clothing is arc-rated.

PRIMARY FR

Protective clothing that is engineered for the primary purpose of providing protection against flame and thermal hazards.

SECONDARY FR

Protective clothing that is designed to be worn with FR clothing without negatively impacting the FR protective levels of the primary clothing. It has basic FR protection and does not ignite and continue to burn once source of flame is removed. However, It should NOT be worn next to skin, rather should be layered over proper FR clothing. Essential for multi-hazard environments.

Learn more about the dangers of burn hazards here.

Browse our Arc Rated and Flame Resistant Clothing.

Learn the difference between Arc Flashes, Arc Blasts, Flash Fire and Combustible Dust.

Arc flash

AR/FR Workwear: Arc Flash vs Flash Fire vs Combustible Dust

by with No Comment AR/FR

ARC FLASH/ARC BLAST

Arc flashes occur when an electric current passes through air between underground and grounded conductors, causing temperatures reaching up to 35000° F. Arc Blasts are waves of pressure that can reach up to 2100 PSI, enough to throw a full grown human and heavy equipment to the ground. Both are serious electrical hazards that can cause serious injuries and fatalities

Arc Flash Prone Industries:

  • Electricians
  • Electrical Engineers
  • Maintenance Techs
  • HVAC Technicians
  • Facility Managers
  • Utilities
  • Electrical Contractors
  • Linemen
  • Inspectors
  • Equipment Installers

FLASH FIRE

Short duration fires, 3 sec. or less, that can spread rapidly through a diffuse fuel, such as gas or the vapor of an ignitable liquid, without producing damaging pressure and reach up to 1900° F. They are characterized by high temperature, short duration and rapidly spreading. Flash Fires can cause severe burns, injuries, and fatalities.

Flash Fire Prone Industries:

  • Oil and Gas Industry
  • Chemical Manufacturing
  • Fossil Fuel Power Generation
  • Plastics Manufacturing
  • Tobacco Manufacturing
  • Pesticides Manufacturing

COMBUSTIBLE DUST

Fine particles (fabric, wood, metals, plastics, chemicals, food products) that can cause fire / explosion when suspended in air. These particles form a dust cloud, and if exposed to a spark or heat, and can ignite and explode. This often occurs during material processing, handling, or storage.

Combustible Dust Prone Industries:

  • Textile Mills
  • Apparel Manufacturing
  • Lumber Mills
  • Paper/Pulp Manufacturing
  • Wood Products Manufacturing
  • Grain Mills
  • Food Processing
  • Machinery Manufacturing
  • Rubber and Plastics
  • Manufacturing
  • Fabricated Metal
  • Product Manufacturing

Learn more about the dangers of burn hazards here.

Learn the difference between types of AR/FR clothing.

Browse our Arc Rated and Flame Resistant Clothing.

ELECTRICIAN

AR/FR Workwear: FR Workwear

by with No Comment AR/FRProtective Workwear

In industries with potential hazards like heat, fire, electricity, or explosives (think construction, oil and gas, firefighting), workers need protection. That’s where flame-resistant (FR) and fire-retardant (FR) clothing come in. These garments are a form of personal protective equipment (PPE) designed to keep workers safe. 

But it’s not just a suggestion – in certain industries and under certain conditions, providing and caring for FR workwear is a strict requirement from the Occupational Safety and Health Administration (OSHA). They demand that workers in specific situations wear clothing that resists burning when exposed to electric arcs and flames. And employers have to foot the bill for providing this lifesaving gear. Employers must do so when:  

  1. The employee is exposed to contact with energized circuit parts operating at more than 600 volts; 
  2. An electric arc could ignite flammable material in the work area that, in turn, could ignite the employee’s clothing; 
  3. Molten metal or electric arcs from faulted conductors in the work area could ignite the employee’s clothing, or 
  4. The incident heat energy estimate exceeds 2.0 cal/cm2 (p. 390). 

But it’s not enough to just have the right clothing – upkeep is vital too. According to OSHA, Employers are responsible for making sure FR garments are properly cleaned and maintained so they don’t lose their protective ability. 

So what exactly is FR clothing? Well, it’s clothing that stops burning as soon as the flame or electric arc is removed. It won’t melt immediately either, which helps prevent burns from residual heat transfer. There are two types: flame-resistant materials, which naturally resist flames and heat, and fire-retardant materials, which have been treated to become flame-resistant. Both offer sufficient protection. 

  • To ensure FR clothing works effectively, OSHA provides some guidelines: 
  • Choose clothing based on the worst-case exposure for the task. 
  • Make sure it fits well and provides comfort. 
  • Roll down and secure sleeve cuffs. 
  • Fully fasten all garments, including outerwear. 
  • Keep clothing free of flammable substances like oil or grease. 
  • Wear appropriate protective coverings for the neck, face, eyes, head, hands, and feet. 
  • All outerwear must be flame-resistant to maintain protection. 
  • Undergarments beneath the outerwear should either be FR or made of 100% natural fibers. 

Now, let’s talk about measuring the protectiveness of your FR clothing – the Arc Rating or Arc Thermal Protective Value. This rating tells you how much heat the fabric blocks when exposed to an electric arc. The higher the arc rating, the more protection you get against severe risks. And it’s measured against the Hazard/Risk Category (HRC) scale, with 1 being the lowest risk and 4 being the highest risk. The minimum arc rating for HRC1 is 4, HRC2 is 8, HRC3 is 25, and HRC4 is 40. 

Here’s a pro tip: Wearing multiple layers of arc-rated clothing will give you even more protection. Some workers swear by wearing 3-4 layers for maximum safety. 

It’s important to note that not all FR clothing is arc rated. To guarantee protection, invest in ARC rated clothing that meets the standards. Also, remember, FR clothing is not fire-proof. If exposed to extreme hazards or for extended periods, the fabric can still heat up or burn, causing serious injury. Avoid synthetic garments underneath FR clothing and remove yourself from hazards as quickly as possible. 

Lastly, keep in mind that FR clothing doesn’t protect against explosive forces or other hazards professionals may face at work. Proper hazard assessment, acquiring all necessary PPE and making sure all PPE functions correctly when used together is essential for complete protection. Your safety matters, so take the time and effort to protect yourself on the job. 

Learn more about the dangers of burn hazards here and browse our Arc Rated and Flame Resistant Clothing.

Read more about protective workwear like HI-VIZ and COVERALLS.

Are you more of a visual learner? Watch our expert led webinar on FR Workwear HERE.

  1. HTTPS://WWW.FROUTLET.COM/BLOG/AN-OVERVIEW-OF-OSHAS-FR-CLOTHING-STANDARDS 
  2. HTTPS://AMERISAFEGROUP.COM/A-BRIEF-OVERVIEW-OF-FLAME-RESISTANT-CLOTHING-STANDARDS-AND-PRACTICES/ 
  3. HTTPS://TYNDALEUSA.COM/FR-SAFETY-RESOURCES/TECHNICAL-LIBRARY/FREQUENTLY-ASKED-QUESTIONS/FLAME-RESISTANT-CLOTHING-BASICS-FAQS/#:~:TEXT=FLAME%20RESISTANT%20CLOTHING%20STOPS%20BURNING,AGAINST%20THE%20SKIN%20%E2%80%93%20IS%20REMOVED 
  4. HTTPS://WWW.POWERMAG.COM/FLAME-RESISTANT-CLOTHING-EVERYTHING-YOU-NEED-TO-KNOW/