IEC 61482 Protective clothing against thermal hazards of an electric arc
This standard has been drawn up for clothing that provides protection against the thermal effects of an electric arc. 
The clothing falls into risk class III: this means that they must be checked annually. The protection against the consequences of 'electric arc' can be tested in two ways.
- IEC 61482-1-1: The "Open Arc" method
- IEC 61482-1-2: The BOX test
With these test methods the cloth is tested and one value is obtained. In addition to the cloth both test methods also test a piece of clothing. No energy value is determined but the garment is checked after exposure to the arc for defects relating to the seams, closures and all other accessories.
How are the clothes tested?
In a box test a mannequin with sensors is placed to cause an explosion. The explosion targets the safety clothing and then assesses how much heat passes through the clothing and whether the garment is damaged as a result of the explosion. Both the cloth and the entire garment are tested. The user must be able to take off the clothing after exposure to an arc, so it is checked whether, for example the zippers and buttons still work as they should.
IEC 61482-1-1: The "Open Arc" Method
The IEC 61482-1-1: The "Open Arc" Method uses an open arc in a medium voltage range (> 1,000V) that is shot to a dummy or fabric sample wearing protective clothing. Electrodes behind the cloth and protective clothing register the heat transfer of the arc through the cloth/clothing. This can be used to determine whether a person has suffered second-degree burns.
In the first step, the fabric is exposed to different energy levels to obtain an approved arc rating. This revised testing method is now more strictly controlled and regulated than before. This may mean that previously obtained results may differ from new tests. However, the protection in the clothing is still the same as before, despite the fact that the Arc Rating sometimes has a lower value after retesting.
In step two the protective clothing is tested with the energy level that the cloth test from step 1 resulted in. A recent change added to the standard is that the tested garment may have an afterburn time of up to 5 seconds to be approved. All tests result in two different arc classifications based on the firing results and the Stoll curve. The latter is used to calculate the chance that a person will sustain a burn.
- The first result ELIM (Incident Energy Limit, cal/cm²) lets the user know how much energy the protective clothing can withstand without any risk of second degree burns. The ELIM value is the official value for arc flash classification according to the new standard and many collections have been updated with an ELIM value.
- The second result is either ATPV (Arc Thermal Performance Value, cal/cm²) or EBT (Energy Break Open Threshold, cal/cm²) and shows the user how much energy the protective clothing will withstand if there is a 50% chance of a second degree combustion. ATPV indicates the energy level required to raise the temperature behind the cloth so much that second-degree burns occur, while EBT indicates the energy level at which the cloth breaks open and can lead to a second-degree burn.
ELIM indicates the Arc Rating for the entire garment. Information such as the ATPV and EBT provide more information. Since ELIM indicates the energy value at which the chance of second-degree burns is 0%, and the ATPV/EBT is a calculation average with a 50% chance of second-degree burns, the ELIM value is usually lower than the ATPV/EBT.
The differences between ELIM and ATPV/EBT emphasize the fact that wearing multiple layers gives the best protection. For example with ARC-related undergarments an extra layer of protection can be created that can reduce or prevent burns.
IEC 61482-1-2: The BOX test
This test method was often used on its own in the past. With this method an arc is generated from one direction (the box) by a short circuit with 168 kJ (4kA (kiloampere) and 400V) for class 1 or 320kJ (7kA and 400V) for class 2. The arc does not last longer than 500ms. The heat transfer is measured and must remain below the Stoll Curve to meet the class. The Stoll Curve is a table that indicates at what temperature and time a second-degree burn occurs. It is also assessed for after-flaming, hole formation, melting and the like.
Unlike the Open Arc test there is no result scale in the clothing tests, but only two levels at which the garment is approved or not. A garment with one layer of flame retardant cloth usually passes APC 1, even a thin t-shirt or shirt cloth. To achieve APC 2, a two or three layer system or a lined garment is usually required. This makes it more difficult to adapt the protection to the risk without sacrificing comfort.
How is the protection class shown?
In the past only the BOX test was usually performed in Europe, so only the APC class 1 or 2 is often known. Some brands such as Tranemo and Portwest already show the ELIM value on newer products. Tranemo even shows the EBT value.
The APC class is shown as 1 or 2, and ELIM and EBT are shown in cal/cm2. As far as possible, we try to mention these classes for all products.