What is Fault Current?

Arc Flash, Fault Current, and OSHA

Electricity, for all its interaction with just about every aspect of today’s modern world, is still a general mystery to the layperson. While we may have a sort of idea of some of the terminology – hey, there was a band called AC/DC after all – most managers aren’t well-educated on electrical workings. This problem is made worse when that manager is in charge of safety operations. Many safety areas are intuitive; avoiding falling objects, preventing slips and falls, etc. all seem easy enough to conceptualize, but electrical current is invisible, and the numbers on a label don’t always convey the immediate potential danger of an electrical mishap.

Each day in America, OSHA reports an average of three to four deaths occur due to a work-related electricity incident. Even with improvement in safety protocols in recent decades, that’s still a large and unfortunate number of workers to be losing each year – especially when such deaths are almost universally preventable. This blog post will not only help to explain some of common workplace dangers associated with workplace electricity, but will also talk about preventative and protective measures. As arc flash incidents remain a prevalent problem, OSHA and other governing bodies continually updates their requirements, so while we’ve striven to provide the most universal and up-to-date information, always check for any stipulations or changes, especially from other work or protective organizations with local jurisdiction in your area.

Fault Current and Arc Flash Resources

To both give you an idea of the resources used and where you can find the most up to date information, here are a few of the most important reference materials when dealing with arc flash and electrical safety:
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  • National Electrical Code: This is the publication from the National Fire Protection Association which outlines various electrical standards and conditions that must be adhered to in order to prevent electrical fires and shocks.
  • NEC: The NEC is also known as NFPA 70, and the NFPA 70E is an OSHA-requested edition which specifically addresses electrical conditions and hazards in the workplace. The current edition of the NFPA 70E is from 2012, though the NFPA’s website states that a new edition is due out in 2015.


What are the dangers associated with electricity in the workplace?

A number of terms are thrown about when it comes to common workplace deaths due to electrical incidents, not the least of which are “fault current,” “arc fault,” and “arc flash/blast.” Let’s go ahead and define a few of these terms now.

Fault Current: When something goes wrong with an electrical connection or system, the resulting altered path of electricity is called the fault current. Fault currents can often be a result of short circuit conditions, in which a disrupted flow of electricity is at an imbalance (so different levels of electricity are occurring at different parts of the same system).

Bolted Fault: When a fault occurs, there are two varieties, of which a “bolted” fault is the first. A bolted fault occurs when there is a physical connection between two pieces of a system. This means that no damage has likely occurred after the fact or during normal operation, and the problem is most likely due to botched installation or maintenance efforts.

Arc Fault: Arc faults are when two differently energized pieces of a system (two wires, for example) are nearby but have no physical connection. This usually results from damage to or severing of an already existing system, and the space in between the two pieces holds the potential for an arc flash.

Arc Flash: If an arc fault contains sufficient energy, it can cause a dangerous electrical explosion, which can produce extreme temperatures and pressures. Because of this, arc flash explosions can kill or injure workers without even being close enough to physically touch or electrocute them. Arc flash incidents are especially dangerous because they can be cumulative, damaging other parts of nearby systems, and will often vaporize the conductors they originate from. This can result in the spewing of molten metal and other dangerous shrapnel-like materials.

Labeling Requirements For Arc Flash Hazards

One confusing labeling conundrum for arc flash hazards is that NFPA 70E (2012 edition) requires that any equipment with arc flash potential be labeled as such. Even so, OSHA only requires that labels on arc flash hazard equipment provide voltage and other basic electrical ratings. Their reasoning is that only qualified workers should be near the equipment and, if properly trained, they will be able to extrapolate from the numbers when a hazard exists.

The reality is, however, that “unqualified” workers may find their way to tampering with electrical equipment in a pinch, and labels should be as blunt as possible to ensure any imminent danger is clearly broadcast to your employees. OSHA recognizes this need and has a few more standards for what information should be included on electrical labels, and what equipment their standards apply to:

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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.[/sws_blockquote_endquote]

Even though it is not required, any energized equipment is a good candidate for labels containing these details. It is also worth noting that, due to the divergent requirements of the OSHA and NFPA standards, two labels are often used to ensure compliance with both. Alternatively, you can combine the information into one label as there is some overlap between the two.
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Producing Arc Flash Labels

When producing your labels, you need to ensure professionalism in both meeting detail requirements and display quality. To do this, especially if you’re going to go ahead and label all energized components, always consider using a professional label printer.

LabelTac printers (which can be found here) are great for printing out high quality and highly customizable labels to satisfy arc flash warning requirements. It is important that labels are able to withstand the daily wear and tear of your workplace, which is one of the reasons we recommend getting a hold of a brand name machine. These machines use durable vinyl labels (like the ones here) to print on and are easily transferred onto any surfaces you’ll need them on.

When designing labels, ensure messages are communicated “at a glance” as well as in depth. This generally means using simple imagery in addition to the required text details of OSHA and NFPA requirements. LabelTac and similar printers are often easily hooked up to a personal computer and used with third-party design programs making this task fairly easy. Even if you don’t have digital design skills, many printers also come with pre-made templates exactly for this purpose.

While there is always a grace period, being able to keep up with changing standards for various safety labels, including but not limited to those associated with electrical safety, is always a plus for any business. Keeping label making efforts in house is one easy way to go about this.