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IEC 61482
Protective Clothing Against the Thermal Hazards of an Electric Arc
The International Electrotechnical Commission (IEC) released IEC 61482, a standard that provides performance requirements and regulates test methods for protective clothing against thermal hazards of an electric arc.
This standard is of paramount importance to all arc flash PPE. The first section of the standard is separated into two parts, each outlining a test that provides different garments properties. A garment can be tested to both test methods. Which standard the garment is tested to is indicated by the standards section number as listed below:
- EN 61482-1-1 Open Arc Test Method
- EN 61482-1-2 Box Test Method
EN 61482-1-1
Open Arc Test
The Open Arc test method is used to determine the arc rating of an FR fabric. The arc rating is expressed as either Arc Thermal Performance Value (ATPV) or Energy Breakopen Threshold (EBT50) in cal/cm2 (calories of heat energy per square centimetre). It is an alternative test to ASTM F1959/F1959M for calculating an arc rating. The Stoll Curve monitors heat and energy transfer rate alongside the rate observed when the garment fabric is used as protection. The result enables a prediction of the point at which the wearer would feel pain, as supported by the Stoll curve.
As of the 2018 version of this standard, garments are also tested and given an Energy Limit Value (ELIM) which complements the ATPV and EBT values for Open arc test. Instead of calculating the incident energy, the garment can withstand before a 50% chance of an onset second-degree burn (like the ATPV test of ASTM F1959/F1959M); EN61482-1-1 calculates the energy level of exposure reached for a 0% probability of second-degree burns. For this reason, ELIM is a more conservative estimation.
EN 61482-1-2
Box Test
EN 61482-1-2, also referred to as the 'Box test' method, is conducted using a plaster box that focuses a short arc toward a rectangular-shaped test sample of the FR fabric placed in a flat configuration.
A quantitative measurement is made by means of the energy transmitted through the material. The standard specifications for this setup is a voltage of 400V, Duration 500ms and a frequency: 50 Hz or 60Hz. Garments are tested to either class 1 or class 2 or both. Electric arc intensity is stipulated as follows:
| Arc Protection Classes | Arc Rating |
|---|---|
| Class 1 | Protection against electric arc 4kA (168kJ) |
| Class 2 | Protection against electric arc 7kA (320kJ) |
The EN 61482-1-2 gives a pass or fail result. To pass this test the garment must:
- Show no evidence of melting through the inner side
- Afterflame less than or equal to 5 seconds
- No hole larger than 5mm in any direction
- All 8 value pairs in testing must be below the Stoll curve
Dependant on the results, the garment will receive either a pass or fail if it has reached or exceeded the Arc protection class rating class benchmarks.