Contents of the Labeling for Arc Flash Hazards Webinar:
- Why Labels?
- Contents of an Effective Arc Flash Label
- What Is Needed to Make Labels?
- From Idea to Reality
Excerpt from the Labeling for Arc Flash Hazards Webinar transcript:
First, why are we talking about labels at all? What’s our goal here?
Safety through Information
In short, safety is the goal. Arc flash is a powerful and dangerous phenomenon, and by the time a flash begins, it’s too late to change what you’re doing. To be safe, workers need to be prepared — and to be prepared, they need to be informed.
Providing that information, where and when it’s needed, is a big step toward preventing accidents and minimizing the damage that they cause. The right knowledge can save lives. That’s what these labels and signs are for.
Arc flash hazard labels are also required by workplace safety laws. In the United States, OSHA will be looking for these labels.
Mark Equipment Ratings as Necessary
On the very basic end, OSHA requires electrical equipment in the workplace to be marked with “voltage, current, wattage, or other ratings as necessary.”
This starts with manufacturer labels, but it doesn’t end there. Employers are responsible to provide the information needed for the use and maintenance of the equipment.
Warn Workers of Electrical Hazards
OSHA gets more specific when it comes to hazards. Specifically, the law mandates the use of safety signs to “…warn and protect employees from hazards which could cause injury due to electric shock, burns, or failure of electric equipment parts.”
This clearly includes arc flash hazards, so labels or signs that warn workers about those hazards are necessary.
Inform Workers of Necessary PPE
Wherever a workplace hazard requires personal protective equipment (PPE), another OSHA requirement comes into play. Employers must determine what PPE is needed, provide that equipment, and communicate the necessary information to employees.
Working safely in the presence of an arc flash hazard requires PPE, so this rule also applies. For the communication part of the rule, labels are a simple and effective solution.
General Duty to Provide a Safe Workplace
Finally, there’s what OSHA calls the “General Duty Clause.” This is section 5(a)(1) of the Occupational Safety and Health Act, the law created by Congress that gave OSHA most of its powers.
The General Duty Clause says that employers have a “general duty” to provide a safe workplace. This is a guiding principle, and brings us back around to the first reason we wanted to have arc flash labels. It’s all in the interests of safety.
Contents of an Effective Arc Flash Label
All right, so you need to protect your workers, and information through labeling is a big part of that protection. What exactly needs to be on an arc flash label, for it to be effective?
This is where the National Fire Protection Association (or NFPA) comes in. Their standard for workplace electrical safety is NFPA 70E, and it describes accepted practices, based on expert opinions and industry consensus. NFPA 70E dedicates a lot of its content to the topic of arc flash safety, specifically including labels.
Obtaining the Necessary Information
Before you can print information on a label, you need to get that information from somewhere. NFPA 70E describes two methods to get that information: analysis and categories.
The Incident Energy Analysis Method
The analysis approach gives you exact details for your specific equipment in your specific installation. Using technical data for the equipment, you can calculate the expected incident energy for a possible arc flash.
Incident energy is the amount of heat (measured in calories per square centimeter) that would hit a surface at the specified working distance if an arc flash occurred. As an example, an incident energy of 1.2 calories per square centimeter is enough to cause second-degree burns — serious, but still treatable, injuries. Higher incident energy means a more powerful blast of heat, and a more destructive result.
The working distance is the distance from the equipment to a worker’s face and chest, often estimated at 18 inches. Because the energy of an arc flash spreads out as it moves away from the equipment, increasing the working distance will decrease the calculated incident energy. It’s important to specify your working distance if you use this approach.
This calculation approach gives the most detailed results, but can involve a lot of technical details and complex math. Electrical analysis software, like EasyPower, can make this approach much easier.
The PPE Category Method
The other approach is a shortcut. Instead of getting exact details for your equipment, you can read a set of tables that the NFPA has prepared. These tables assign one of four broad categories to common situations.
If your equipment and installation are covered in those tables, all you need to do is find the entry that applies, and you can use the published recommendations for your category. Each category (numbered 1 to 4) has an associated list of required PPE, along with minimum ratings for that protective gear. That’s why this approach is called the Arc Flash PPE Category method.
The tables don’t cover all situations, though, and if your installation isn’t covered, the category system simply can’t apply.
In the past, a lot of people tried to use both systems at the same time, calculating the Incident Energy and then assigning an Arc Flash PPE Category as well. This is specifically prohibited in the current edition of NFPA 70E, because the PPE Categories are based on the NFPA’s fairly conservative estimates for common situations, while the Incident Energy calculations are up to the employer’s detailed math for the exact equipment and installation being described. Mixing the two systems can cause contradictions and confusion. It also makes it difficult for a reader to check the information, or for you to update it in the future.
In general, if your project is fairly small or uses only common equipment, the category approach can save time and effort. For larger facilities or more specialized situations, analysis is probably called for.
NFPA 70E Equipment Labeling Elements
The 2018 edition of NFPA 70E, in Article 130.5(H), lists the following details as required for an arc flash label:
• the Nominal System Voltage;
• the Arc Flash Boundary; and
• at least one of the following:
o the Incident Energy and Working Distance, or the Arc Flash PPE Category, but not both;
o the Minimum Arc Rating of clothing;
o and/or a site-specific identification of required PPE.
I’ve had a lot of questions about the details of these elements and the choices that are involved, so I’ll briefly explain each part of the requirement.
Element 1 – Nominal System Voltage
First, there’s the nominal system voltage, or the “voltage class” for the equipment. This is usually the easiest detail to track down, and it serves as a quick and simple indicator for the power of a system.
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