Arc flash calculations assume the door is open. Â This arc flash video shows why. Â Although not an extreme amount of short circuit current for this test, it is enough to create enough blast pressure from the arc flash and blow the door open. Â Do the doors blow open for every case? Â No. But it is difficult (impossible?) to determine if it will so to be conservative, it is assumed the doors are open. Â This video was from arc flash testing by Jim Phillips for IEEE 1584 to determine the behavior of the arc based on the electrode orientation.