For updated methods, see IEEE 1584-2018.įull Interactive Calculator Arc Flash Boundary Calculator - Doughty Method | DesmosĬurrent, Time, Distance: To know exactly how big a hazard you might be dealing with you need an Arc Flash Hazard Study. Change the size of the arc flash by adjusting the time and current.īased on Doughty et. Explore the importance of distance with arc flash hazards. This is an embedded interactive graph for understanding where the arc flash energy is related to distance.

If each ray (red lines) in the graphic above provides 1.2cal/cm2, the arc flash boundary would be set at the distance where only one ray goes through an area (A) within a limited amount of time (2 seconds). The intensity is inversely proportional to the distance squared. The heat radiated from this arc is what burns you, but as radiant heat decreases by the inverse square law as it travels (see image below). It’s caused by an electrical arc sustained in plasma, after the current flow has been initiated and is sustained across the conductor gap. Incident energy is a measure of radiant heat released for a given surface are. Technically: It’s the approach limit from an arc source at which the incident energy equals 1.2cal/cm2. An electrician determines the hazard from an arc flash label and sets up a zone around the work location to alert people of the safe distance.įor more information on what an arc flash hazard study includes see this, Arc Flash Study Services. Since the risk of arc flash isn’t always present the alerting methods are temporary. The boundary is just a number on the label until an electrician opens something up exposing live conductors and does a task that could potentially start an arc flash. This distance can be found on an arc flash hazard label which is applied to each piece of equipment included in an arc flash hazard study. The bigger the arc flash, the further it goes. Practically: It’s determined mostly by the size of the arc flash.

Where does the Arc Flash Boundary come from? It’s calculated as the distance from the arc source for the hazardous energy released to drop to 1.2cal/cm2.įor a more look at the some of the calculations, see this blog, What is the Arc Flash Boundary? - Arc Flash Boundary Calculation Without the right protection equipment covering your entire body, the safe distance you must be is the arc flash boundary. So still not super safe, but not life threatening.Īrc flash PPE protects against the short burst of intense radiant heat that is released from an arc up close. With an arc flash boundary that hazard is the onset of a 2 nd degree burn.

In the safety world, a boundary is an approach limit to a hazard. The largest boundary sets the approach limit and determines where a barricade should be set up to alert others. Typically, the arc flash boundary is the largest boundary, but in some cases the shock hazard limited approach boundary can be larger. For more on Arc Flash ‘Working Distance’ and Shock Approach Boundaries, see this post, Arc Flash Boundary: Working Distance & Approach Distance Explained We’ll look at how that safe distance is communicated, where it comes from, what it means, and who’s responsible for it. For everyone else that means keeping a safe distance. For electricians, this means wearing the right PPE when they get up to work. We’re going to look at the arc flash hazard. Essentially the closer you are to the arc the hotter it gets.įor someone working on or near exposed parts that have an arc flash hazard, the important thing to know is how bad it could be…this is called the ‘Incident Energy’. With electrical equipment there are two main hazards to consider, shock and arc flash.

Arc flash boundaries definitions