Arc Flash: Identifying & Reducing Hazards in Your Electrical System

Two often overlooked steps in an Arc Flash Study are the Coordination Study & Mitigation Strategies.  Simply put, these are the steps that actually make the electrical system safer and reduce risks.  There are many reasons that companies implement an arc flash study.  They can include compliance, corporate policy or even insurance requirements.  But let’s not forget the main reason that they are required by NFPA 70E in the first place: To Create a Safer Working Environment and Reduce the Risk for Personnel Working in or Around Live Electrical Equipment. 

That is the bottom line. That is our goal: Safety and Risk Reduction.  Coordination and Mitigation actually accomplish this goal and reduce the risk.  So what exactly is coordination and mitigation?  Glad you asked.


A coordination study is a detailed engineering analysis of the electrical system which identifies areas in your system where the over-current protective devices might not open in the proper sequence.  Over-current protective devices include breakers, fuses, relays, etc. and are designed to be the last line of defense in the event that a fault occurs in the electrical system.  If there is a fault or an arc flash event in a downstream breaker panel, ideally we want the breaker closest to that panel to be the breaker that opens and clears the fault rather than an upstream breaker further away from the incident.  This accomplishes two goals: First, the fault is cleared faster.  Second, the loss of power is isolated to a smaller area.

In a system that is not coordinated the fault may pass through one or more breakers to an upstream breaker before the fault is cleared.  This takes longer to happen and creates much more heat and energy at the location of the fault placing any personnel in a dangerous situation.  In addition, the loss of power affects a larger portion of the electrical system.

It is not uncommon to have coordination issues in an electrical distribution system, especially as it ages and changes are made over time.  Case in point: a hospital in which we recently completed an arc flash study had a major coordination issue.  A problem in a 30 amp breaker far downstream from the main switchgear was causing the Main Breaker (3000 amp) to trip.  This is a major coordination problem, and as you can imagine, is not ideal for a hospital.  In performing the coordination study for this hospital, our engineers were able to recommend trip setting adjustments on the main breaker to fix the problem.  From an operational and safety standpoint this was a huge benefit for the facility.  See figure below for details.

This is a snapshot of coordination recommendations to eliminate nuisance tripping of Main Breaker. Changing the old settings to the new settings (in red) created a safer and more reliable electrical system

This is a snapshot of coordination recommendations to eliminate nuisance tripping of Main Breaker. Changing the old settings to the new settings (in red) created a safer and more reliable electrical system

It is not uncommon to find dozens of coordination issues inside an electrical system when we provide arc flash studies to our customers.  Each one of these issues, when identified and corrected, may reduce the hazard throughout the facility and protect the worker.


Mitigation involves actually reducing the incident energy inside an electrical panel.  Incident Energy represents the degree of hazard inside each electrical device and is measured in cal/cm2.  The higher the incident energy, the greater the hazard and the more intense a potential arc flash would become.  Through mitigation, we can identify the devices that contain high incident energy and explore ways to actually reduce that value.

Let’s look at an example.  In conducting a recent arc flash study we analyzed a 480V distribution panel that had an incident energy of 38.2 cal/cm2.  This level of energy requires Category IV PPE, which is hot and cumbersome to work in.  By performing a mitigation analysis, we were able to identify alternate trip settings to the breaker feeding the panel that would reduce the Incident Energy to 0.7 cal/cm2 which only requires Category I PPE. This is a huge reduction in risk and danger and reduces the arc flash boundary from 12 feet to 12 inches.

Let’s repeat that again. 

  • Incident Energy was reduced from 38.2 to 0.7
  • PPE necessary was reduced from category IV to category I.
  • Arc Flash Boundary was reduced from 144 inches to 12 inches.

Any time we are able to reduce the incident energy it creates a safer working environment, reduces risks and makes the job easier for the person doing the work.  It is not uncommon for our engineers to find multiple opportunities to reduce the incident energy in just one facility. As a matter of fact, at a recent hospital in Florida, we were able to identify over 50 areas in which we could reduce the hazards from Category III or IV down to a Category I hazard.

Bottom Line

A coordination study and mitigation strategy should always be a part of an arc flash study.  They are the only steps that can actually identify techniques and changes that will reduce the hazard levels inside your electrical system.  It is common for our engineers to identify dozens of areas inside an electrical system that can be made safer through coordination and mitigation, and many times these changes are simple settings on a breaker.

Again, arc flash studies are often implemented as a result of compliance, but let’s not forget what they are designed to do which is save lives and prevent catastrophic injury to workers.  An effective arc flash hazard survey that includes a coordination study and mitigation strategy accomplishes both.

Workplace Safety Training: Why it’s critical

Imagine this scenario: “Tom,” is a new employee in your plant’s maintenance department. As the plant supervisor, you ask “Joe,” your maintenance supervisor, to help Tom learn the job and show him the ropes. You specifically tell Joe, “Remember to show him how to de-energize the machines before he works on them.”

So Tom shadows Joe for a few weeks, helping him with several maintenance projects, including a number of machine repairs. Since he’s your maintenance supervisor, Joe always de-energizes the equipment. He ”gets it,” and he does a great job of telling Tom how important it is to de-energize the machinery before working on it.

After a few weeks on the job, Tom (who happens to be a quick study) is familiar with the plant, knows the machinery, and is sufficiently engaged and knowledgeable to handle a number of things on his own. One morning, just a few minutes before the first shift, your most important piece of equipment breaks down. Joe is on vacation, but Tom is well aware that losing this particular machine shuts down your entire assembly process, so he is on the spot to fix it. In his enthusiasm to prove himself, however, Tom forgets to de-energize the machine. He crawls between the back of the machine and the wall and removes the rear cover to expose its inner workings.

Now that the machine is open, Tom slips on his leather gloves, puts on a pair of goggles and uses a screwdriver to remove a few screws inside the machine. This allows him to reach the gear box, which he does successfully.  He notices that one of the gears – measuring 18” in circumference – is missing a couple of teeth, so he reaches in to start removing it. That’s when Phil, the machine operator for the first shift, hits the “start” button.

At that moment, Tom’s right hand has a good grip on top of the gear, his left hand is holding the bottom of the gear, and he is about to pull the entire gear toward him to remove it from its spindle. As the machine is started, the gear turns counter-clockwise. Before Tom can remove his hands, they are both caught between the defective gear and the two adjacent gears. As Tom’s hands are crushed, Phil can’t hear Tom’s screams over the motor. After a few seconds the machine jams and Phil scratches his head. He hits the “Stop” button and then hears Tom’s agonizing screams. Tom is rushed to the hospital, where doctors proceed to remove what’s left of his hands.

As is the case with any workplace injury, OSHA comes in to see what happened. Their inspectors learn that Joe trained Tom, that he showed Tom how to de-energize the machinery, and that he even emphasized how important it is to do so. They learn that there was even some discussion about using personal protective equipment, as evidenced by the fact that Tom was wearing gloves and safety glasses.

However, there is no documentation, meaning there is no evidence that your company provided formal training for any of your employees. Further, it’s clear to the OSHA inspectors that your firm doesn’t have a formal policy on de-energizing or otherwise disabling (think “lockout/tagout”) machinery before someone works on it.

The result of all this? Tom has lost both hands and is now unable to tie his shoes, much less hold a job. He will undergo countless surgeries, a lifetime of physical and occupational therapy, and his marriage and family will experience great stress. OSHA cites your company for a number of safety violations, imposing fines in the six-figures. And Tom sues your company for failing to train him adequately, which of course, results in his inability to earn a living. Based on his age at the time of the accident (31) and a lifetime of expected earnings, he is awarded several million dollars. And you’ve lost your job.

If you think this scenario is a stretch, think again. As in this fictional account, many employers equate “training” to “showing someone the ropes,” but it is far more than that. Specifically, OSHA expects that every employer will have a formal training program in place, along with formal policies and procedures related to workplace safety. OSHA also expects that every employee will be required by their employer to abide by those policies and procedures, and OSHA holds the employer accountable if the employee fails to do so.

Hopefully, this account has you thinking about your training program and whether it is adequate or not. If it is adequate, you are to be congratulated! However, if it is inadequate, you may have some work to do. As experts in workplace safety, Mitchell & Lindsey is here to help. Give us a call at (502) 682-8491 for a free consultation.

For those who doubt: Multiple cases point up the frequency of electrical hazards

When safety violations and citations are looked at separately, it’s easy to assume that they don’t happen very often. But that’s not necessarily the case.

In fact, a handful of citations announced by the Occupational Safety and Health Administration (OSHA) during a three-day period in May indicates that safety violations happen quite often, and it’s not always the scofflaws who are cited. The point is that every company – even those that think they are doing a good job in regard to workplace safety – needs to pay close attention to details.

Case in point: Suburban Propane Partners, Ft. Worth, Texas: Suburban Propane is of the nation’s leading marketers of propane gas, fuel oil, and related products and services. One would think that a company whose primary business is dealing with a highly flammable material would know that allowing electrical hazards in a propane-filled environment is a bad idea. Even so, OSHA cited Suburban Propane for using temporary electrical cords as permanent electrical wiring and for several other electrical wiring violations. Proposed fines: $114,000. OSHA News Release:

Case in point: Allied Metals, LLC, Miami, Florida: Allied Metals was cited for 17 serious safety violations, including exposing workers to hazards such as electrocution, and to amputation hazards from cutting machinery that lacked guards. Other violations included exposing workers to electric shock from improperly spliced power cords. Proposed fines: $57,600. OSHA News Release:

Case in point: Sifco Industries Inc., Cleveland, Ohio: Sifco, which makes products for the aerospace and energy industries, was cited for failing to conduct annual inspections and testing its procedures to keep machines from starting unintentionally, failing to install safety guards on presses, and failing to develop specific procedures to prevent machines from starting unintentionally during service and maintenance. This latter violation included failure to attach locking devices when workers change mechanical parts. Proposed fines: $118,400. OSHA News Release:

Case in point: Recycling Revolution, LLC, Unadilla, Georgia: Recyling Revolution is a solid waste collection and processing company. They were cited by OSHA for 14 repeated and 12 serious violations, including not establishing procedures to protect workers from accidental machine startup while performing maintenance and services. Proposed fines: $78,078. OSHA News Release:

Case in point: Alfa Laval, Inc., Broken Arrow, Oklahoma: A global provider of heat transfer, centrifugal separation and fluid handling products, Alfa Laval was cited in part because it had no procedure to prevent machines from starting during maintenance or service. Alfa Laval was severely penalized, because an OSHA inspection found dozens of serious workplace safety violations – five of which were identified in previous inspections. Proposed fines: $477,900. OSHA News Release:

In each of these cases, the employers were cited not because there was an accident, but because of their failure to take proactive steps to prevent an accident. It’s interesting to note that these citations were among nearly 30 announced by OSHA between May 18 and June 8, 2015. Several others included violations related to electrical safety, but every one reflects some degree of failure on the part of an employer. It’s also interesting to note that the companies cited were both large and small, well-known and not well known, and they are located all over the country. While OSHA reports that some of these employers are repeat violators, it’s probably safe to say that most of them did not willingly – or in some cases knowingly – violate safety procedures.

Even in the most innocent of cases, however, OSHA is very clear, so there should be no mistake: The employer is – without any shadow of a doubt – responsible for ensuring that workplace safety standards and procedures are in place. Employers have been cited even in cases where employees willfully ignored safety procedures, because of their failure to enforce those procedures.

As a CEO, facility manager or plant supervisor, you can stick your head in the sand in an attempt to avoid these issues, or you can deal with the issue proactively. Either way, you’re going to have to deal with it. I would argue that it’s better to do so on your own terms rather than OSHA’s.

Do you have questions about workplace safety? We’re experts. Call us at (502) 682-8491.