An arc flash occurs when there is a short circuit through the air between conductors or conductors and ground, such a flash will result in numerous hazards such as: extreme temperature, explosive forces, toxic smoke and fumes, high noise levels, hot liquids, fast moving debris and very bright lights.
There is a general hazard and potential risk of human injury due to electric arcs, particularly in the case of fault arcs which may internally occur with short-circuits in electric installations. These arcs cannot be avoided totally. It is very important for the personnel mounting, repairing, maintaining or operating electrical equipment and installations to be safely protected in every situation.
Reliable tests are necessary to confirm the clothing is arc resistant and guarantees the protective level required. Test method, procedure, set-up and parameters must meet the according practical needs. The test conditions have to be selected and terminated in accordance with the relevant power network and installation ones, and the practical exposure scenarios as well. Furthermore, quantitative assessment and evaluation is necessary in testing. The calorimetric arc effects are to be measured and a calorimetric analysis of the tests has to be carried out.
New Arc Flash Standards and Requirements:
IEC 61482-1 and the identical EN 61482-1 are split into two parts, which cover the methods for testing of clothing fabrics and garments that are designed to protect against arc flashes.
IEC 61482-1-2 and the identical EN 61482-1-2, which now supersedes ENV 50354, have become known as the "Box Test".
There are two test method versions: The "material box test", which includes heat transfer measurements and Stoll curve differential analysis, and the "garment box test", which requires only a visual assessment of the garment performance.
The box-test standard defines two test conditions, namely Class 1 and Class 2:
Class 1 tests at an arc current of 4kA and arc duration of 500 ms.
Class 2 tests at an arc current of 7kA and arc duration of 500 ms.