IEC 61482-2:2009

Live working - Protective clothing against the thermal hazards of an electric arc - Part 2: Requirements

This part of IEC 61482 is applicable to protective clothing used in work if there is an electric arc hazard. This standard specifies requirements and test methods applicable to materials and garments for protective clothing for electrical workers against the thermal hazards of an electric arc based on – relevant general properties of the textiles, tested with selected textile test methods, and – arc thermal resistance properties, such as - the arc rating of materials (ATPV or EBT50), when tested with an open electric arc under defined laboratory conditions according to IEC 61482-1-1, or the arc protection class of materials and garments (Class 1 or Class 2), when tested with a directed and constrained electric arc under defined laboratory conditions according to IEC 61482-1-2. Requirements of this standard do not address electric shock hazards.

This standard specifies requirements and test methods applicable to materials and garments for protective clothing for electrical workers against the thermal hazards of an electric arc based on Arc thermal resistance properties, such as:

• The arc rating of materials (ATPV or EBT50), when tested with an open electric arc under defined laboratory conditions according to IEC 61482-1-1, or
• The arc protection class of materials and garments (Class 1 (4 kA) or Class 2(7 kA)), when tested with a directed and constrained electric arc under defined laboratory conditions according to IEC 61482-1-2.

Terms and definitions

ATPV (arc thermal performance value)
In arc testing, the incident energy on a material or multilayer systems of materials that results in a 50% probability that sufficient heat sufficient heat transfer through the tested specimen is predicted to cause the onset of a second degree skin burn injury based on the Stoll curve, without break open.

EBT50 (break open threshold energy)
Incident energy on a fabric or material that results in a 50% probability that sufficient heat transfer through the tested specimen is predicted to cause the tested specimen to break open.

ATPV and EBT50 are expressed in kJ/m2 or kW s/m2 (cal/cm2).
Correlation 1 cal/cm2 – 41,868 kJ/m2, 1 kJ/m2 = 0,023885 cal/cm2.

Stoll curve
Curve of thermal energy and time produced from data on human tissue tolerance to heat and used to predict the onset of second degree burn injury.

Testing
The protective clothing covered by this standard shall have certain resistance properties to the thermal effects of an electric arc.
Two international test methods have been developed to provide information on the resistance of clothing to the thermal effects of electric arcs. Each method gives different information.
To be in accordance with this standard, a product shall be evaluated by using IEC 61482-1-1 or/and IEC 61482-1-2. Depending on the needs, the users will specify for one test method or the other.
Material test as well as garments test shall be performed. For garment certification both the material and garments shall fulfil the requirements.
When tested according to IEC 61482-1-1, the protective clothing made of the tested material shall be assigned a corresponding ATPV of the material. A protective clothing will demonstrate a minimum arc thermal resistance, if the ATPV is at least 167.5 kJ/m2 (4 cal/cm2). The higher is the ATPV value, the better is the thermal resistance under high incident arc energy (higher current value, longer exposure time).
When tested according to IEC 61482-1-2, the protective clothing made of the tested material shall be assigned a Class 1 or a Class 2 depending of the test conditions and the resulting arc thermal protection. A protective clothing will demonstrate a minimum arc thermal protection, if it passes the Class 1 test. A Class 2 indicates a higher arc thermal resistance.
In case that no ATPV can be determined, the EBT50 shall be determined and assigned to the tested material. The minimum EBT50 demonstrated by the material shall be at least 167.5 kJ/m2 (4 cal/cm2).