Protective clothing against thermal hazards of electric arc
Norm: Draft IEC 61482-2 – Supersedes CLC/TS 50354:2003 (or ENV 50354)
The garment must be used in combination with other clothing that ensures protection in compliance with EN 61482-1. No undergarments, such as undershirts and underwear, which melt under arc exposure are to be worn. The garment is tested using an arc voltage of 400 V and an arc duration of 500 ms.
Class 1 protects against an arc current of 4kA with a duration of 500ms
Class 2 protects against an arc current of 7kA with a duration of 500ms.
An electric arc or blast as a result of a disruption (e.g. a short circuit) in an electric installation generates a sudden release of intense heat and light causing serious burns, blindness or even death.
This blazing bright electric discharge between two conducting electrodes
- lasts for a very short time (0.5s, 1s and rarely >1s)
- develops a very strong radiant heat (several thousands °C)
- creates high physical forces, a pressure wave and pressure shrapnel
- a splash of molten metal particles or even vaporized metal
- up to 165 db noise.
IEC 61482-2 specifies requirements applicable to materials and garments (excl. protection of head, hands and feet) for protective clothing for electrical workers against the thermal hazards of an electric arc. The requirements do not address electric shock hazards nor the effects of noise, UV emissions, pressure shrapnel or toxic influences.
This International Standard specifies performance requirements for materials and design requirements for PPE used for protection against electric arc.
Garments can only be certified for the IEC 61482-2 Standard if the fabric performance requirements meet the IEC 61482-1-1 or the IEC 61482-1-2:
• IEC 61482-1-1 is called the ‘open’ arc method. During this test, the resistance of a fabric against an electric arc will be calculated, which is called the Arc Thermal Performance Value (ATPV) and expressed in cal/cm2. The end user can select the correct fabric for his garment by ensuring the ATPV of the fabric is greater than the incident heat energy of the arc. If a Company is operating in an environment where potential electric arcs will not supersede 10 kA, a fabric with an ATPV more than 10 would be suitable for the protective garments. This method is used in the USA.
• IEC 61482-1-2 is called the box test. During this test, the fabric will be tested against an electric arc of 4 kA and 7 kA. If the fabric passes the test of 4 kA, it is certified as Class 1. If it passes the test of 7 kA, it is classified as Class 2. This method is used in Europe.
Next to the fabric performance requirements, the Standard prescribes many garment design requirements.