Arc Flash Hazard Analysis
By Steve Hudgik
Concerning arc flash hazard analysis, the Informative Annex F of NFPA 70E states:
“Hazard identification and risk assessment are analytical processes consisting of a number of discrete steps intended to ensure the hazards are properly identified and analyzed with regard to their severity and probability of their occurrence.”
According to Annex F what needs to be done is:
- Identifying and analyzing electrical hazards
- Identifying tasks to be performed
- Documenting hazards associated with each task
- Estimating the risk for each hazard/task pair
- Determining the appropriate protective measures needed to adequately reduce the level of risk
Real-world advice and insight into preventing arc flash accidents.
NFPA 70E 130.3(B)(1) requires that, for any energized electrical conductors or circuit parts with 50 volts or more, that are not in an electrically safe work condition, safety-related work practices must be determined before anyone is exposed to the electrical hazard. This is done by conducting both a shock hazard analysis and an arc flash hazard analysis.
NFPA 70E 130.5 states: “An arc flash hazard analysis shall determine the arc flash boundary, the incident energy at the working distance [the distance of the face and chest from the arc source], and the personal protective equipment that people within the arc flash boundary shall use.”
The NFPA 70E code also requires that the arc flash hazard analysis be updated whenever a major modification has been made. In addition, the arc flash hazard analysis must be reviewed at least once every five years.
One of the results of an arc flash hazard analysis is that the arc flash boundary is determined. What is the definition of the arc flash boundary? It is the distance at which the incident energy equals 5 J/cm2 (1.2 cal/cm2). The distance is defined as the distance from the face or chest, whichever is closer, to the arc source.
An arc flash hazard analysis consists of three electrical system studies:
- A short circuit study. The short circuit study checks protective device ratings within a power system and ensures they are adequate for the maximum currents that may flow during a fault condition.
- A protective device coordination study. This study is also required by section 240-12 of the NEC. A protective device coordination study analyzes the characteristics the breakers and fuses. These characteristics are plotted to identify any areas of overlap. The objective is to ensure a short circuit only affects the portion of the system where the fault occurs...
- An flash-hazard analysis. The arc flash hazard analysis provides a detailed assessment of the potential energy at each point in the system that would be released in the event of an arcing fault within the equipment.
Arc flash-hazard analysis are often performed by an engineering consultant. Another option is to use arc flash hazard analysis software and in-house engineers to do the arc flash hazard analysis.
Once the arc flash hazard analysis is complete the information is used for making arc flash labels. This provides the necessary warning information directly at the point of the hazard. DuraLabel printers are the only arc flash label printers that not only provide database software for designing, saving and printing arc flash labels, but also give you a variety of label size options. Call 1-888-326-9244 and ask about the DuraLabel arc flash labeling kits. You'll be glad you did.