The Importance of Arc Flash Analysis
Why Do Arc Flash Analysis (aka Flash Hazard Analysis)?
At the risk of sounding overly dramatic, the answer is: because people die.
Now it's hardly news that arc flash is deadly, and there is no one working in the industry today that is not already acutely aware of the danger. Everyone's heard that arc flash explosions can burn hotter than the surface of the sun, and if you haven't, well, they can. A December '07 article in the Journal of Safety Research said, "Next to the laser, the electric arc is the hottest event on earth, with recorded temperatures as high as 35,000° F" (Kowalski-Trakofler, Barret 598). That's pretty hot, so if you didn't know, now you do.
Arc Flash happens just like ... "that."
And the flames can spew like dragon's fire.
Engineers, electricians and contractors need to know EXACTLY where the dragon might decide to breathe.
Here's an illustration of standard "safe" distance calculations.
... Clearly, someone's math was wrong ...
An Inch is NOT as Good as a Mile
"Yeah, yeah," you might be saying, "I get the point. It's hot; it's scary; it's unpredictable. Very interesting, but so what? Everyone knows arc flash is hot. That's why we have warning labels and personal protective gear (PPE). Or even better, turn the system off and don't get burned at all." Right?
Well, yes, technically that's correct. But knowing what is supposed to be done is not the same as doing it.
Studies Show It’s Not Just the “Rookies” Getting Hurt
The article mentioned above was based on extensive research done on arc flash injuries in the workplace (with particular focus on mining related electrical safety). They interviewed over 800 arc flash victims for the article. One of the project's primary discoveries was that many of the previously held beliefs about "experience" being the key to preventing injuries turned out to be unfounded. In fact, what the authors discovered was that:
In Phase One incidents [arc flash victims from a statistically viable sampling spanning 11 years], it was determined that in a substantial number of instances the worker recognized the hazard and made a decision to proceed with behavior that led to the incident. In practically every interview in Phase Two [conducted with selected industry and mining arc flash victims], the issue of making a judgment/decision to complete an assignment by taking a short-cut was mentioned even though the worker knew it was wrong to do so. (Kowalski-Trakofler, Barret 605)
So what these researches found out was that people working in the field made bad calls. They took "short-cuts" which turned out to be "judgment/decisions" that went wrong, and they got burned. They did so regardless of experience. Generally, the study determined that this was because the victims were in a hurry for one reason or another (pressure from management/customers or other factors), or because it was late in the day and they were tired. Experience is of little use when someone's in a rush or no longer thinking straight.
Another article, appearing in Power Engineer (Nov 2007), summed up this idea by saying, "You hear many stories of people who have been involved in flashover incidents and very often the age of the victim is 40-plus years old, which shows that experience is not always a solution to this problem" (Phillips, Frain 34). The point being, even if you have a seasoned crew, or even if you are the seasoned crew, mistakes happen.
"So what," you might still be saying. "Mistakes do happen. Sure fatigue or rushing is a problem. I can't control that sort of thing. Get to the point!"
Alright, with that other stuff established, I will.
What CAN Be Done to Prevent Arc Flash Injury and Death
While it's true that training, supervision and a positive safety attitude toward guidelines and regulatory practices in a workplace go a long way to preventing injury, the fact is that no amount of training or management can prevent human error.
However, there are some things completely in our control, and there are errors that can be prevented with far greater consistency. Those errors lie in the accuracy of our math, which in turn involves some other critical details.
NFPA 70E [130.3 (a) and (b)] states explicitly that that flash hazard analysis has to be done to determine energy exposure levels, protection boundaries and what, specifically, constitutes adequate PPE for any work space where arc flash can occur. There are even guidelines and tables to help electricians out. Again, this is probably not news to most people in affected industries. But what many people aren't considering at all is how accurate is the math?
Phillips and Frain point out, "NFPA 70E provided generalised tables based on the task, hazard and associated risk that can be used for the selection of PPE" (37). The operative term here is "generalised," meaning, not precise for any specific job.
Now while for many things in life generalized math is fine - like rough estimates of how much you're 401K will be worth in five years or how high the price of gas will be six months from now - for calculating boundaries where 35,000° F explosions can occur, "generalized" math is just not the kind of thing I'm all that comfortable with. Are you?
Calculating Arc Flash Analysis Correctly is Difficult to Do
Yep, it is. Even Phillips and Frain agree. On the issue of doing arc flash studies they admit, as you may already know, that "The most comprehensive approach for conducting an arc flash study is to perform calculations based on IEEE 1584." However, how often does that actually occur? They go on to say "that the more detailed IEEE calculations can be quite laborious" (37). And they are. That's why people aren't using them often across lines of Industry. "Laborious" is not a happy word. It's generally associated with great pains and considerable expense.
Can you still do this?
What's worse is that the authors of this study, as do most of us, also recognized that "the accuracy of any study is only as good as the input data [,] and system studies should always take account of variables due to changes in system configuration for example. For this reason only trained individuals should undertake arc flash calculation" (37). Given the complexity involved, it's not really a stretch of logic to agree. Someone needs to know what they're doing before they start calculating flashover figures that impact people's lives.
But what usually happens, given that so few people are actually equipped for or even capable of doing the calculations the way they are supposed to be done, is that businesses and contractors settle for the "generalised" numbers instead. Just go to the chart and reckon it's good enough.
If you're one of those people, don't feel bad. You're hardly alone. However, that doesn't mean you shouldn't do something to mend your engineering ways.
It’s Not Just Life and Limb; It’s Money Too.
We're not talking about "doing it right" money either, not money for the right materials or the right crew. We're talking about straight up liability. If you miss the radius on a protection zone by even as little as an inch and somebody gets hurt, you just put everything you've ever worked for on the line. As Phillips and Frain pointed out, "The US is a more litigious society than the UK and there are even legal textbooks written on how to pursue a damage claim brought about by electrical accidents" (34).
"Litigious" in this context means that "American's like to sue." And they do. And not only do they like to sue; their lawyers are going to college and taking fancy classes for the sole purpose of coming after you on arc flash related claims. That means the lawyers know how this stuff works too.
But you can protect yourself, not only from physical harm, but from financial harm as well. All you have to do is do accurate math - granted, the math they were calling "laborious" up there a few paragraphs ago, but hey, at least it's in your control. And even if the functions of arc flash analysis aren't really your forte, you're still the problem solving type. Do what you always do: go out and buy the tool.
Frightening Flash Hazard Tools
But that's the frightening part. One of the scariest things out there right now is the easily availability of FREE tools being distributed online. This freebie software, along with lots of other cheap software - and, frankly, even some of the so called "good stuff" - is being sold and used for flash hazard analysis with what seems like little concern for accuracy at all.
Keep in mind we're talking about 35,000° F here; this ain't flicking a match out of the matchbook at your buddy back in high school anymore. This is life and death stuff. And people are using cheap software to do these "quite laborious" tasks.
And I'm going to repeat what I said a minute ago about the NFPA 70E: while it is an excellent source for what it represents, the tables are generalized. Generalized is easier to do than "laborious" that's true, but when we are dealing with life and death, and perhaps even scarier, with drooling lawyers studying deeply in special text books on how to make you pay for any errors in your math, do you really want to run with just "generalized" arc flash analysis?
And how good do you think the calculations you can get for free on the Internet are going to be? We all know you get what you pay for. And we're not talking about free video games right now.
There is software out there today that can do the "laborious" math quickly and more easily than can the cheap stuff being pushed off on people over the Internet. In fact, arc flash computations can be pretty painless now given how user friendly and graphical some modern software has become. Painless and accurate. The right program can keep the lawyers chasing someone else's ambulance and you and your crew out of one, and it's all about accuracy.
The free and the cheap software all share one fatal flaw: they don't allow you to include every component in the system that you need to analyze.
To return to the article by Phillips and Frain again: It should always be remembered that the accuracy of any study is only as good as the input data and system studies should always take account of variables due to changes in system configuration (37).
Well, if the software you are using doesn't allow for the input of the entire system, meaning all of it not just some, then the "accuracy" of the work you are doing with that software is "only as good as the input data" that's getting entered in. If portions of a system being designed or evaluated are being left out because the software doesn't allow for anything but the major components to be factored in, well, then the "input data" isn't very good at all. That's scary considering all that's riding on the math.
How much fun do you think a lawyer could have with your bank account if he found out your "detailed arc flash analysis" skipped all the small details along the way? Hawaii anyone?
Accurate Arc Flash Analysis
So the key point of this article ultimately comes down to accuracy. Arc flash analysis is a fact of life now. You have to do it. You have to put the signs up, you have to keep the PPE on hand and you are going to be held accountable for the computations you hang your customer's and your employee's safety on.
Basically in today's environment there's three ways to go about it:
- Use generalized info from NFPA 70E.
- Use a cheap or free software program and hope it works out long term.
- Use a program (or someone with a program) capable of doing the job right.
Currently the only software program available that allows for total system input down to the last wire and watt is put out by a company called Dolphins Software. The program is called Volts, and, frankly, it's not cheap. However, it does allow for complete system input and therefore dead-on accuracy when calculating arc flash values, and it makes it very easy to "take account of variables due to changes in system configuration" as was mentioned up above.
Have a look at the Volts website yourself. You'll see what I mean about how in depth the computational capacity is and yet how easy the graphic interface is to use. I would say a monkey could use Volts, but that's probably hyperbole, so just go have a look. When you're done, go look at the other stuff out there and you'll totally understand why I brought the Dolphins Software program up.
The Bottom Line in Flash Hazard Analysis
The bottom line is; times are changing. The powers that be aren't going to let companies, contractors and engineers lean back and "reckon that'll do" any longer when it comes to arc flash analysis. Technologies are advancing every day, and equipment - industrial and in the home - becomes more complex with each advance. Modern day electricians, contractors and engineers can't be satisfied with just "generalized" any more. And if they are, well, I hope their insurance is paid up, and I hope their conscience is clear.
Other Resources You Can Use
- VOLTS (Dolphins-software.com)
This is the program I mentioned. There's a ton of good information on this site. Yes, they're selling something, but that doesn't mean they don't have important things to say. (Check out their testimonials client list! These guys don't mess around)
- Excellent Arc Flash Source - Training, Forums and more.
This is an excellent site for arc flash training and information. There are user forums covering all elements of arc flash including Saftey, IEEE 1584, NPFA 70E, PPE and numerous other categories.
- NFPA homepage
There are many, many links and articles available here, as well as links to order NFPA 70E and various other sources that you may need.
- OSHA (U.S. Department of Labor) homepage
If it's OSHA related, you can get at it here. Great online resource.
- US Department of Labor
Statistics on injuries and deaths along with other important and ever-changing information.
- Web based arc flash safety training is available.
I can't personally speak for the quality of this training, but the research I did for this project was done in academic and peer reviewed material (not all of which made it into the article itself), but several sources spoke highly of this program.
- Journal of Safety Research home
Online source for Internet access to the first article that I referenced in my piece. However, it's not free. If you have access to a college or public library Internet service, you can read the article for free through EBSCO.
- IET Power Engineer (IEEE home)
Homepage for IEEE and for the other article referenced in my piece. Again, it's not a free access site, but the work is good and frequently peer reviewed. Library or University access through EBSCO will get you to the article I referenced.
- Electric Panel Explosion
Brief NFPA account of fatal "real world" accident that was thoroughly investigated and the resultant conclusions that the investigation came up with; one of which (there are four) was that arc flash analysis needs to be properly done and details why.
Kowalski-Trakofler, Kathleen, and Edward Barrett. "Reducing Non-contact Electric Arc Injuries: An Investigation of Behavioral and Organizational Issues." Journal of Safety Research 38.5 (2007): 597-608. Academic Search Premier. EBSCO. California State University of Sacramento Lib. 25 June 2008. <www.sciencedirect.com>.
Phillips, Jim, and Mike Frain. "Fear of Flashover." Power Engineer 21.3 (2007): 34-37. Academic Search Premier. EBSCO. California State University of Sacramento Lib. 25 June 2008. http://web.ebscohost.com.