Page 40 - Occupational Health & Safety, September 2018

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A good label should include incident energy at a working distance, information about PPE require- ments, voltage, a warning sign saying “arc flash hazard,” and a flash protection boundary.
you can do step three. One-lines can be of CAD quality with the reverse-study method, and the computer-generated software one- line could be, too.
Step three for the data collection/engineering study method is to go back into the field and apply the labels. Now, you’re done with labeling compliance. However, employees need to have training and proper PPE so they know how to work safely; workers need oversight to successfully work around hazards. Having labels with warnings on them is just one piece of the pie when it comes to a robust electrical safety program.
Mitigation of High Arc Flash Hazards
What about mitigation of high arc flash hazards identified and co- ordination of protective devices? With the reverse-study method, high arc flash hazards should be noted on ESWP forms (electrical safety work process forms) or some other kind of form. An ESWP form can note the code violations mentioned before and note high- level PPE warnings applied with the tables. An engineer can look at the form and determine whether a localized coordination study is needed to lower a setting and reduce the risk. Most all devices on site are fixed fuses or breakers; by looking in the NEC, one can determine whether a fixed trip breaker can be sized to a lower size.
With the other method (data collection/engineering study) these things are picked up when the arc flash study is completed and recommendations are made to management in a report to cor- rect these issues and apply labels later when the recommendations are implemented. Either way, the fixes mostly include retrofitting fixed trip breakers and fuses with new ones, and lowering settings on large power breakers.
Good Arc Flash Labels
With either method, a good label should include incident energy at a working distance, information about PPE requirements, volt- age, a warning sign saying “arc flash hazard,” and a flash protection boundary. Shock protection boundaries and the “shock hazard” warning sign also may be included.
Cost and Time Savings
A reverse-study means savings on cost and time. It doesn’t take as much time to just go and apply labels in one step. The potential is for compliance to increase when cost and time are reduced. If you determine to take on the arc flash hazard where you work, or go through the five-year redo process per NFPA 70E, you might just want to be done and compliant sooner than later, especially if you have a lot of scope. With the reverse-tables, the idea behind the table method is to apply labels only once and then as needed for new installations and retrofits.
Disadvantage of Reverse-Study Arc Flash Tables
There is one disadvantage to the tables—in a few spots, it can be conservative, but it shouldn’t be by much. The engineering study
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ELECTRICAL SAFETY