Re: Arc Flash Warning Labels
I would like to chip in on this topic. I feel strongly that the manufacturer of the panel should not apply the arc flash labels; rather, it should be up to the system designer/installer or the system owner/operator. Here's why:
The panel manufacturer can only identify the short circuit rating of the panel (e.g., 50kA), but would have no way of knowing how much fault current is actually available at the panel, which is the requirement for the 70E flash hazard analysis. The available short circuit current at the panel is determined by the system voltage and upstream impedance. A typical available fault current for a 240V, 50kVA transformer is around 7-8 kA. This would allow the flash protection barrier to be reduced to only 7 inches, if the program is under engineering supervision.
Also note that the arc-flash warning label is only needed if there is a possibility that the panel will be worked live, and working in an energized panel is prohibited except under a couple of limited conditions. If there will be no work in a panel in the vicinity of exposed energized conductors, then there an arc-flash warning label is not needed on that panel. So it would not typically be appropriate for a panel manufacturer to apply an arc-flash hazard warning label, when a flash hazard may not exist in that panel as it is not intended to be worked hot.
