Protective clothing against the thermal hazards of an electric Arc
ProGARM produces safety garments that protect workers against the Thermals Hazards of an Electric Arc. Each garment style is carefully designed to offer the maximum protection whilst ensuring comfort and outstanding durability. As Arc Flash garments come under the requirements of Category 3 Protective Clothing, these garments are manufactured under Article 11B Quality Control Procedures.
What is an Electric Arc?
Electric Arc and the Arc Flash created is an extremely dangerous and least understood hazard of electricity. It occurs as a result of extreme discharges of voltage or electrical current from equipment including switchgear, transformers and heavy electrical equipment. The Arc generates a high level of energy for a very short span of time (up to 1 second). The intense heat can create temperatures as high as 19,000°C and it also produces electric shock, force and large quantities of thermal radiant energy.
What is the Risk?
In any situation where your employees are working with electricity, an Arc Flash can occur and as such the maximum energy of default circuits in any electrical installation must be able to be determined. The risks of an electric Arc exposure are:
- Electrocution – potentially fatal
- Extremely high levels of Radiant Heat
- 1st, 2nd or 3rd Degree burns – 3rd Degree burns cause permanent damage
IEC 61482-2:2009 Performance & Design Requirements
Performance requirements for materials and design requirements for garments, plus Marking and User Information.
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 worn by electrical workers to protect them against the thermal hazards of electric Arc based on relevant general properties of the textiles, tested with selected textile test methods, and one of the Test Methods as defined below.
IEC 61482-1-1:2009 'Open Arc' Test Method
'Open Arc' test method (ATPV test and garment test). This replaces IEC 61482-1:2002. The 'Open Arc' test method is the same as the original North American method for measuring the Arc Thermal Performance Value (ATPV), as used in ASTM F1959. Materials or assemblies are given an ATPV value, expressed in kilojoules per square metre (kJ/m2), which can be converted into the familiar cal/cm2.
IEC 61482-1-2:2007 'Box Arc' Test Method
'Box Arc' test method (Fabric classification and garment test). The ‘Box Arc’ test method is based on the original European method described in ENV 50354, with a heat transfer measurement. Materials or assemblies are classified as Class 1 (4 kA) or Class 2 (7kA). During this test, a fabric sample is exposed to an electric Arc produced by a 4kA or 7kA short circuit. In the test, the Arc does not last any longer than 500ms. The amount of heat transmitted through the sample is measured during and after the test. On the basis of the resulting data and a Stoll curve, the length of time it would take to cause the onset of second-degree burns is subsequently determined. Samples are also assessed for after-flaming, hole formation, melting, etc.
Garment Testing & Fabric Testing
It is important to note that not only the fabric should be tested for conformance to the Arc Flash Standard, but also the complete garment or garment assembly itself. The garment test is not testing for energetic value but is testing to ensure that the garment structure remains intact after the Arc exposure and that components such as zippers and buttons are still functional and do not contribute further injury to the wearer by melting or heat transfer.
Limitations of Use
With Arc protection, the environmental conditions and the risks at the working site shall be regarded. For example a test under the standard using a 4kA test current (Class 1) subjects the garment/fabric to an incident energy of 135 kJ/m2 ± 56 kJ/m2 (3.2 ± 1.2 cal/cm2) over a 500ms exposure at 18-28°C at 45-75% RH. If the working environment deviates from this temperature/humidity range the level of protection may be reduced. Exposure to higher incident energies or longer duration Arcs may result in the garment providing insufficient protection. Therefore risk assessments should be conducted prior to live working.
For full body protection, the protective clothing shall be worn in the closed state and other suitable protective equipment (e.g. helmet with protective face screen, protective gloves and footwear (boots) shall be used. No garments such as shirts, undergarments or underwear should be used which melt under Arc exposures - e.g. made of polyamide, polyester or acryl fibres. For maximum protection against Arc Flash Exposure garments should be worn as part of a layering system i.e. in conjunction with a shirt or other undergarment.
Warning: tears to Arc Flash certified garments should not be repaired by the user; a flammable (not flameproof) thread or heat reactivatable piece likely to melt would be very dangerous in the event of exposure to flame. Should there be any need to repair a garment, please contact ProGARM for details on how this is best undertaken.