A warning potential arc flash hazard label is critical to fulfilling the National Electric Code's requirement for field marking potential arc flash hazards. A proper arc flash label includes the arc flash hazard and shock hazard boundaries as well as the appropriate combined level of PPE.
Warning potential arc flash hazard labels which clearly identify equipment and components are important for elimiating confusion. In some instances, it may also be appropriate to provide labels with maintenance or cleaning proceedures.
To ensure you have a safe workplace, and that you are meeting NEC, OSHA, IEEE and NFPA* requirements, use specialized arc flash analysis software to calculate protection boundries. These include the Flash Protection Boundry, Limited Approach Boundary, Restricted Approach Boundary and the Prohibited Approach Boundary.
To improve safety and worker compliance, additional information can be included on the label including the flash hazard boundary, working distance and required PPE. When additional labeling is included, it must be assured that the information is understood by everyone required to work on the equipment. Too much information that is unclear to the workers will be ignored and can be as bad, if not worse, than no information at all. It is extremely important the labeling is as clear and accurate as possible. While it is obvious that insufficient PPE is dangerous, over-clothing workers can also increase the risk of an
arcing fault due to limited mobility and visibility.
Large equipment such as switchgear can often have different levels of incident energy due to feeder and protective device configuration. Multiple labels can also be placed on a single piece of equipment depending on the access point and proximity to the arc source for a given activity. However, it is good practice to provide a single label for the largest incident energy available. Workers should not enter the flash protection boundary to work on live parts unless they are wearing the proper PPE for the level of hazard that could occur. The specific flash protection boundary, working distance, and incident energy values should be readily accessible to all workers, either identified by an equipment mounted label, or otherwise documented and available for reference or review.
Arc Flash Boundaries
The limited, restricted and prohibited approach boundaries stated on an electrical safety warning label.
Arc Flash Protection Boundary
This boundary number on the lable dictates the nearest anyone may approach without the use of PPE. In order to determine the flash protection boundary, you need to know the available short circuit current, predicted fault duration and the voltage.
Limited Shock Approach Boundary
The shock approach boundary number on an electrical safety label may only be crossed by an "unqualified" person when they are accompanied by a "qualified" person.
Arc Flash PPE Required
Personal Protective Equipment (PPE) level is dependent on the incident energy at every point a person may perform work on energized electrical equipment. An electrical engineer or other qualified person should first perform the calculations that determine incident energy. Appropriate PPE should cover all parts of the body of the worker that may be exposed to an explosion. This could include shoes, gloves, flame resistant clothing, safety glasses, etc.
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