Two years ago, I wrote a book called “ I Know My Shoes Are Untied. Mind Your Own Business ”. Many people assume that the title is just me being a curmudgeon, but the real story behind the title is much more interesting.
Years ago – long before I was dragged kicking and screaming into the field of worker safety – I worked as a consultant in Organisational Development to help save a dying auto plant. I wasn’t required to wear steel or compositetoed shoes, but there was one thing the safety officer insisted on: that my shoes be tied. I have never liked tying my shoes and throughout my life I have stumbled on untied shoes only a handful of times and have never once tripped. In safety terms my risk tolerance for walking around with untied shoes is extremely high, but the safety officer disagreed. One day he said to me, “La Duke, if I see you with your shoes untied one more time I will put you out of the plant.” I’m not sure he had the ability to do that, but I wasn’t going to risk my job over it. That night I went out and bought the style of shoes that required no laces. That shut him up.
What does this have to do with arc flash? Am I just giving you a glimpse into the rich tapestry that is my life? No. You see, as I walked the aisle out into production multiple times every day I walked by an induction hardener. I will explain what that means for the many of you who don’t work in manufacturing. There are several types of induction hardening, but one of the quickest and most reliable ways of hardening metal parts involves passing a part through an intense electrical field that is stronger than a bolt of lightning.
I became friends with the operator, Ron, and enjoyed talking to him about his plans for the weekend, or his grandkids that he loved. And then one day while I was preparing my daily walk to the floor I was stopped by the safety officer who said Ron was dead. I managed to stammer out “…how?” He either didn’t know or wouldn’t say, but I later learned that the electricity arced and connected with Ron’s wedding ring, sending a bolt of plasma. It’s important to note that the presence of metal itself is unlikely to have been a factor in the arc flash itself, but the extremely high temperature was enough to melt the metal on his body and molten metal on your body is no joke. The blast heated his body to 19,430°C (three and a half times the average surface temperature of the sun, which comes in at 5,505°C). Ron died almost instantly. What does that have to do with me tying my shoes? Well the safety officer was more concerned about me tying my shoes than me being in close proximity to the intense, magnetic field while wearing a metal watch, having a metal pen in my pocket, and wearing a metal belt buckle. I often think about all that metal melting into molten metal against my skin… meaning the risk of me dying from an arc flash was far more likely than dying from untied shoelaces. Only those of us who have lost family, friends, or co-workers can truly appreciate the stunned horror of someone who is in good health being there one day and dead the next.
“the blast heated his body to 19,430°C, three and a half times the average surface temperature of the sun”
What is arc flash?
I will spare you the highly complex definition of arc flash and state it simply: anywhere there is high voltage there is a fairly strong likelihood that an arc flash occurs. A finger of superheated plasma strikes out like some diabolical creature looking for someone to touch with its finger of death. Dave Johnson, Editor in Chief of Industrial Safety and Hygiene News (ISHN) reports that the number of arc flash incidents are as high
as 30,000 annually in the United States alone.
And from these incidents:
- 7,000 burn injuries per year
- 2,000 hospitalisations per year
- 400 fatalities per year
- 80% of electrical worker fatalities are due to burns, not shocks1
I think this last bullet is worth noting: More people die from arc flash incidents than they do from being electrocuted. I want you to think about that for a second. You are more likely to die from arc flash than from electrocution, and yet while most people I know have a healthy respect for electrocution and take every measure available to avoid it, too few even consider the dangers of arc flash.
Can arc flash be prevented?
Amanda Green asserts arc flash can indeed be prevented. She said: “Can arc flash be prevented? Yes. Let’s start by exploring what arc flash is. Arc flash is an electrical current that jumps from the desired path and travels through the air from one conductor to another.”2. Imagine a bolt of lightning veering off course. It has the potential to ignite clothing and burn workers. Anyone in the path of the electrical discharge or in the vicinity can be severely injured or even killed.
Factors affecting arc flash injuries
All of these are good tips, but most of us already know that we should do these things.
In fact the best protection for the average worker is clothing designed to protect one from arc flash injuries. But when should we wear this protective equipment? I don’t know about you but I’m not about to wear it to the beach.
Writing for EC&M, Arc Flash expert, James White, offers the following: “There are five primary factors that determine the severity of an injury from an electrical arc:
- Distance from the arc
- Absorption coefficient of the clothing worn
- Arc temperature
- Arc duration • Arc length3
What he is saying in effect, is that if you aren’t in an area where high voltage is present you probably don’t need to wear PPE to protect your from arc flash, but if you are in close proximity to high electrical sources you need to be on the alert.
Protection from arc flash
Writing for Nova Medical Centre’s website, Jessica Hurd offers the following tips for protecting yourself from an arc flash4:
“Arc Blast Awareness – As the Arc Flash explosion emits heat and light, there is also a pressure wave present which is the Arc Blast. An Arc Blast is a highpressure sound wave caused by a sudden arc fault. The risk of the Arc Blast is also a risk factor in the electrical field. Arc Blast can cause a person to be blown off their feet. Other injuries include loss of memory or brain function from a concussion, hearing loss and physical injuries from being blown off ladders, into walls, etc.
According to Electrical Engineering Portal, blast pressures can exceed 2,000 pounds per square foot, knocking workers off ladders or collapsing workers’ lungs. These events occur very rapidly with speeds exceeding 700 miles per hour making it possible for a worker to get out of the way.” Although the author doesn’t describe this as a tip, I think it qualifies. In my case, the safety officer should have conducted a safety talk with anyone who would traverse that aisle about the dangers of arc flash. I would have been an easy, quick solution, but not as easy as telling me to tie my shoes.
The author offers these tips:
- “De-energise – No one has ever reported having been killed or injured from an arc-flash while working on de-energised equipment. If there is no option for equipment to be deenergised, electrical workers must be “qualified”, trained, wear appropriate personal protective equipment and follow all applicable OSHA standards to minimise risk factors.” This is certainly an important tip; however, Ron couldn’t de-energise his equipment and still do the job, and it would never be de-energised except for breaks and off-hours so anyone using the main aisle was still at significant risk.
- “Lockout/Tagout – This refers to making sure that machines are turned off, locked and go through routine maintenance or service work before being able to be operated again. Always remembering to de-energise and follow established lockout/tag out procedures can save lives.” Here again, this wasn’t an option for Ron.
- “Always Wear Personal Protective Equipment (PPE) Properly –The hazards of arc flash and arc blast are very similar to the hazards faced by firefighters, which explains why their protective equipment is similar.” This is a good tip, but you have to know there is a danger before you can don the protective equipment.
“arc blast can cause a person to be blown off their feet, injuries include concussion, hearing loss and physical injuries”
Causes of arc flash incidents
While the incidents are widely believed to be random and unpredictable, there are several risk factors that increase
the likelihood of an arc flash, including:
- Improperly installed equipment
- Electrical equipment that is damaged – Dented electrical boxes – Corroded contacts – Rusted electrical enclosures
- Improper tool use – Using a screwdriver as a chisel or lever – Connecting circuits with a screwdriver, and number of stupid, jury-rigged, “temporary fixes” of machinery
- Improper maintenance or installation of equipment: – Replacing fuses with a coin – Using a wire gauge that cannot properly sustain the amount of electricity flowing hrough it – Poorly installed or worn-out insulation or exposed wiring – Cleaning components with reactive or flammable materials
- Power surges or overloading the system • Unprotected human contact with energised equipment
Amanda Green2 advises: “The most obvious and best way to prevent an arc flash is to work on de-energised equipment. If there is no current flowing through a device, there will be no arc flash. Sometimes, however, it is necessary to work on energised equipment or on equipment whose status is unknown. In these circumstances, it is important to work with your safety specialist to find the proper hand protection for working with energised circuits.”
Arc flash PPE
When you come into contact with a temperature that is hotter than the surface of the sun, there isn’t much chance that you are going to emerge
unscathed, but there is PPE that can significantly reduce the severity of your injuries and can literally be the difference between life with a minor scar, and death or crippling injury.
It bears repeating that you should never attempt maintenance or installation of equipment without controlling all hazardous energies, particularly electricity (in this case) but many people may unknowingly be working on equipment that is energised and so it is prudent to wear the appropriate PPE even if you are absolutely, unconditionally and without a doubt positive that the equipment isn’t energised. That may seem like wearing your seatbelt while parked in your car, but better safe than burned beyond recognition.
So, when working with anything with the potential of causing an arc flash, wear the following PPE.
Gloves are your first line of defence against arc flash injuries because typically your hands will be in closest proximity to the source of the flash (wires, damaged or overloaded equipment, etc.) The most important consideration in selecting gloves is whether or not they are rated for arc flash protection; this information is available from the manufacturer – don’t gamble with your life: if you aren’t sure of the glove’s rating look it up.
Another consideration when selecting gloves is the conductivity of the materials; most gloves manufactured to protect against arc flash are made of rubber, cotton or wool treated to make them more resistant to electricity, or leather. In my opinion, leather offers the best protection, and I base this solely on the fact that I have never heard of a cow being killed by an arc flash. But seriously, the greatest danger from arc flash isn’t electrocution, it is from extreme heat. Rubber gloves are not very good conductors of electricity, but the extreme heat is likely to melt them against your skin – still better than hot plasma on bare skin, but take it from a man who spent the better part of his childhood melting plastic toys it is going to hurt like… well, decorum dictates that you think of the most painful thing you can imagine and fill in the blank, but a lot. Treated gloves offer greater protection but less flexibility reducing your manual dexterity, and leather gloves offer the greatest protection but the least manual dexterity. I like leather gloves because I have never met a person whose gloves melted against his hands who said, “I may have burned my hands horribly, but at least I was dexterous.” Of course, there are standards and ratings for gloves depending on your specific purpose, but these standards and ratings are too varied and expansive to include here, so you can look them up as your situation warrants.
“gloves are your first line of defence against arc flash injuries because typically your hands will be in closest proximity to the source of the flash”
Arc flash face shields
If your hands are the body parts in closest proximity to an arc flash, your face comes a close second. An arc flash face shield can mean the difference between being devastatingly handsome like me and looking like Frankenstein’s Monster. The arc flash face shield forms a physical barrier between your face and the blast of energy. You may still get injured but these injuries are going to be far less severe than if no barrier existed.
Leather welding apron
The biggest complaint I hear about wearing a leather apron is that it is hot. Well, it isn’t 3.5 times hotter than the sun. Welders wear aprons to keep sparks from contacting their skin or clothes, and while you don’t hear much about leather aprons in the context of arc flash, seriously – what harm can it do?
Flame resistant (FR) clothing
The biggest advantage of FR clothing is that it doesn’t burst into flames or melt against your skin when it is exposed to an ignition source. A lot of people are severely injured from non FR clothing melting or catching on fire and this is completely foreseeable and preventable. When selecting FR clothing be sure to obtain the proper rating for your job, and also be mindful that laundering and normal wear of FR clothing can dramatically lower its ability to protect you, so be sure to follow the manufacturer’s recommendations for care and replacement of FR clothing.
FR hoods are a great way to protect your entire head from burns. A lot of people forget that hair is flammable, and a lot of bald people believe that their lack of hair somehow offers more protection. Either way I recommend wearing a FR hood when working on or around equipment that are at risk of producing an arc flash. Aside from the obvious burn protection, when worn with a flash face shield and other protective clothing you’ll look like a comic book superhero, and for my money it’s worth it just for that alone.
- Arc flash statistics, Dave Johnson, ISHN, 5/31/13: www.ishn.com/ articles/96001-arc-flash-statistics
- How to Choose Gloves to Protect Against Arc Flash by Amanda Green, OHS magazine 02/01/17: ohsonline. com/Articles/2017/02/01/How-toChoose-Gloves-to-Protect-AgainstArc-Flash.aspx
- The Five Most Important Factors Affecting Arc Flash Injuries by James White, EC&M 05/11/15: www.ecmweb.com/safety/arc-flash/ media-gallery/20902054/the-fivemost-important-factors-affecting-arc- flash-injuries
- How To Protect Yourself From Arc Flash Incidents: Don’t Let Your Life Flash Before Your Eyes by Jessica Hurd, Nova Medical Centers: n-o-v-a. com/blog/how-to-protect-yourselffrom-arc-flash-incidents/