Live working – Protective clothing against the thermal hazards of an electric arc – Part 1-2: Test methods – Method 2: Determination of arc protection class of material and clothing by using a constrained and directed arc (box test)
|Publication Date:||1 January 2007|
|ICS Code (Ignitability and burning behaviour of materials and products):||13.220.40|
|ICS Code (Electrical equipment for working in special conditions):||29.260|
|ICS Code (Other electrical equipment for working in special conditions):||29.260.99|
This part of IEC 61482 specifies methods to test material and garments intended for use in heat- and flame-resistant clothing for workers exposed to electric arcs. In contrast to the test methods in IEC 61482-1-11) a directed and constrained electric arc in a low voltage circuit is used to classify material and clothing in defined arc protection classes.
The test methods specified in this document are aimed at rendering a decision whether arc thermal protection is met under defined conditions. Two protection classes are tested. Protection class 1 and protection class 2 are safety requirements covering actual risk potentials due to electric fault arcs.
NOTE 1 In practice there can be higher risks. A risk analysis should clarify the actual risk.
The test methods are not directed toward measuring the arc thermal performance value (ATPV). Methods determining the ATPV are prescribed in IEC 61482-1-1.
This standard specifies tests with which it is possible to evaluate materials and protective clothing based on the use of a directed and constrained electric arc under defined laboratory conditions (box-test). A practical scenario concerning test set-up and test conditions, electrical and constructional parameters is selected.
For the tests a low voltage procedure is used. The tests can optionally be carried out in two fixed test classes, selected by the amount of prospective short circuit current:
Class 1 4 kA;
Class 2 7 kA.
The defined duration of the electric arc is 500 ms in both test classes.
NOTE 2 These conditions represent e.g. low voltage environmental conditions during an electric fault.
Materials and clothing will be tested with two methods: the material box test method and the garment box test method.
The material box test method is used to measure and find material response to an arc exposure when tested in a flat configuration. A quantitative measurement of the arc thermal performance is made by means of the energy transmitted through the material.
The garment box test method is used to test the function of the protective clothing after an arc exposure, including all the garment findings, sewing tread, fastenings and other accessories; no heat flux will be measured.
Testing refers to the thermal arc effects; it does not apply to other effects like noise, light emissions, pressure rise, hot oil, electric shock, the consequences of physical and mental shock or toxic influences.
1) IEC 61482-1, Ed.1 (2002) is currently under revision. The next edition will be numbered IEC 61482-1-1.