IEC 61482-1-1:2019

Live working - Protective clothing against the thermal hazards of an electric arc - Part 1-1: Test methods - Method 1: Determination of the arc rating (ELIM, ATPV and/or EBT) of clothing materials and of protective clothing using an open arc

IEC 61482-1-1:2019 specifies test method procedures to determine the arc rating of flame resistant clothing materials and garments or assemblies of garments intended for use in clothing for workers if there is an electric arc hazard.
An open arc under controlled laboratory conditions is used to determine the values of ELIM, ATPV or EBT of materials, garments or assemblies of garments.
NOTE 1 The user can, if he desires, classify the arc protective performance into arc rating protection levels based on ELIM, ATPV and/or EBT values which correspond best to the different hazard and risks levels that can result from the user’s risk analysis.
NOTE 2 This document is not dedicated to classifying the arc protective performance of the material and clothing into arc protection classes. Procedures determining these arc protection classes APC1 and APC2 are specified in IEC 61482 1-2, which uses a constrained arc for testing.
NOTE 3 This test method is not intended and not appropriate to evaluate whether materials or garments are flame resistant or not, as this is covered in IEC 61482-2.
Other effects than the thermal effects of an electric arc like noise, light emissions, pressure rise, hot oil, electric shock, the consequences of physical and mental shock or toxic influences are not covered by this document.
Protective clothing for work intentionally using an electric arc, e.g. arc welding, plasma torch, is not covered by this document.
This second edition cancels and replaces the first edition published in 2009. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
- addition of the Incident energy limit (ELIM) as a further arc rating performance property value;
- replacement of char length requirement in the scope by indication that Procedure A is applicable for testing of materials meeting the limited flame spread requirements of IEC 61482-2;
- clarification of the definition and the meaning of the Stoll curve;
- modification of specification of positioning of monitor sensors with respect to the electric arc as function of intended high incident energy exposure of test specimens;
- modification of specifications of monitor sensor construction;
- specification of black paint;
- elimination of calorimeters from the chest of the mannequin;
- specification for possible positioning of mannequin(s) at a height different from the centre of the electric arc and possible turning in order to adequately expose all parts of the garment or clothing which would affect performance;
- more explicit description of requirements for data acquisition system;
- preconditioning of the samples;
- modification of requirements for apparatus and arc exposure verification by bare shots;
- more explicit description of test procedures A and B, in particular the subclauses dealing with “sequence of test”, “test parameter” and “test criteria”;
- addition of determination of arc rating values of garments and/or garmet assemblies.
Key words: Protective Clothing, Thermal Hazards, Open Arc, Arc Rating

Travaux sous tension - Vêtements de protection contre les dangers thermiques d'un arc électrique - Partie 1-1: Méthodes d’essai - Méthode 1: Détermination de la valeur assignée d’arc (ELIM, ATPV et/ou EBT) des matériaux pour vêtements et des vêtements de protection utilisant un arc ouvert

IEC 61482-1-1: 2019 définit des procédures d’essai permettant de déterminer la valeur assignée d’arc des matériaux pour vêtements et des articles d’habillement ou assemblages d’articles d’habillement résistant à la flamme, destinés à être utilisés dans les vêtements pour travailleurs en cas de danger d’arc électrique.
Un arc ouvert dans des conditions de laboratoire contrôlées permet de déterminer les valeurs de l’ELIM, de l’ATPV ou de l’EBT des matériaux, articles d’habillement ou assemblages d’articles d’habillement.
NOTE 1 L’utilisateur peut, s’il le souhaite, classer les performances de protection d’arc en niveaux de protection des valeurs assignées d’arc sur la base des valeurs ELIM, ATPV et/ou EBT qui correspondent le mieux aux différents niveaux de danger et de risque, que l’analyse du risque par l'utilisateur peut produire.
NOTE 2 Le présent document n’a pas pour objet la répartition des performances de protection d’arc des matériaux et des vêtements en classes de protection d’arc. L’IEC 61482 1-2, qui utilise un arc contraint pour les essais, spécifie des procédures de détermination de ces classes de protection d’arc APC1 et APC2.
NOTE 3 Cette méthode d’essai n’est ni destinée ni appropriée à l'évaluation du caractère de résistance à la flamme ou non des matériaux ou des articles d’habillement puisque cela est couvert par l’IEC 61482-2.
Le présent document ne couvre pas les effets autres que thermiques d’un arc électrique, comme le bruit, les émissions lumineuses, l’augmentation de la pression, l’huile chaude, le choc électrique, les conséquences d’un choc physique ou mental ou des effets toxiques.
Le présent document ne couvre pas les vêtements de protection utilisés pour réaliser des travaux utilisant intentionnellement un arc électrique, par exemple un soudage à l’arc, une torche à plasma.
Cette deuxième édition annule et remplace la première édition parue en 2009. Cette édition constitue une révision technique.
Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
- ajout de la limite d’énergie incidente (ELIM – Energy Limit) comme valeur de propriété supplémentaire relative à l’application de la valeur assignée d’arc;
- remplacement dans le domaine d’application de l’exigence concernant la longueur de carbonisation par une indication de l’applicabilité de la procédure A pour l'essai des matériaux satisfaisant aux exigences concernant la propagation limitée de flamme spécifiées dans l’IEC 61482-2;
- clarification de la définition et de la signification de la courbe de Stoll;
- modification de la spécification de placement des capteurs de surveillance par rapport à l’arc électrique en fonction de l’exposition des éprouvettes d'essai à une énergie incidente élevée;
- modification des spécifications de constitution des capteurs de surveillance;
- spécification de la peinture noire;
- suppression des calorimètres de la poitrine du mannequin;
- spécification du placement possible du ou des mannequins à une hauteur différente par rapport au centre de l’arc électrique et de la rotation possible permettant une exposition appropriée de toutes les parties de l’article d’habillement ou du vêtement qui altèrent les performances;
- description plus explicite des exigences concernant le système d'acquisition de données;
- préconditionnement des échantillons;
- modification des exigences concernant la vérification de l’appareil et de l’exposition à l’arc par des tirs à blanc;
- description plus explicite des procédures d'essai A et B, notamment les paragraphes qui traitent de la «séquence d’essai», du «paramètre d'essai» et des «critères d’essai»;
- ajout de la détermination des valeurs assignées d’arc des articles d’habillement et/ou des assemblages d'articles d’habillement.
Mots clés: Vêtements de protection, dangers thermiques, arc ouvert, valeur assignée d’arc

General Information

• Status: Published
• Publication Date: 02-Jul-2019
• ICS: 13.110 - Safety of machinery
• ICS: 13.220.40 - Ignitability and burning behaviour of materials and products
• ICS: 25.040 - Industrial automation systems
• ICS: 29.020 - Electrical engineering in general
• ICS: 29.260.99 - Other electrical equipment for working in special conditions
• Technical Committee: TC 78 - Live working
• Drafting Committee: WG 15 - TC 78/WG 15
• Current Stage: PPUB - Publication issued
• Start Date: 03-Jul-2019
• Completion Date: 14-Jun-2019

Relations

• Revises: IEC 61482-1-1:2009 - Live working - Protective clothing against the thermal hazards of an electric arc - Part 1-1: Test methods - Method 1: Determination of the arc rating (ATPV or E_BT50) of flame resistant materials for clothing
• Effective Date: 05-Sep-2023

Overview

IEC 61482-1-1:2019 is an international standard developed by the International Electrotechnical Commission (IEC) focused on the testing of protective clothing against the thermal hazards posed by electric arcs. Specifically, it defines test methods using an open arc to determine the arc rating of flame-resistant clothing materials, garments, and garment assemblies intended for live working environments where electric arc hazards are present.

This standard specifies how to measure critical arc rating values such as the Incident Energy Limit (ELIM), Arc Thermal Performance Value (ATPV), and/or Breakopen Threshold (EBT) by exposing test specimens to controlled electric arc conditions in a laboratory setting. The results from these test methods assist users in assessing and selecting protective clothing to minimize thermal injury risks from electric arc flashes.

Key Topics

• Test Methods (Procedure A and B): Procedure A focuses on testing material samples using panels, while Procedure B tests actual garments or garment assemblies on mannequins. Both procedures use calibrated calorimetric sensors and controlled open arc exposure to quantify thermal resistance.

• Arc Rating Parameters:

  • ELIM (Incident Energy Limit): The maximum incident energy the protective clothing material or garment can withstand before failure.
  • ATPV (Arc Thermal Performance Value): The amount of incident energy on the fabric that results in a 50% probability of causing a second-degree burn.
  • EBT (Breakopen Threshold): The incident energy level at which the fabric or garment physically breaks open, exposing the wearer to thermal injury.

• Open Arc Test Conditions: The standard employs an open arc configuration under strict control to simulate realistic electric arc exposures while providing repeatable and reproducible results.

• Instrumentation and Calibration: Details on apparatus construction, sensor types, and calibration procedures are included to ensure accurate measurement of thermal energy transmission through clothing materials.

• Sample Preparation and Conditioning: Guidance is provided on cleaning, pre-treatment, and mounting of materials and garments before testing.

• Data Reporting: The standard outlines requirements for comprehensive test reports, including arc ratings, sensor data, test parameters, and visual inspections of tested specimens.

Applications

IEC 61482-1-1:2019 is essential for manufacturers, safety engineers, and testing laboratories involved in evaluating and certifying protective clothing designed for workers exposed to electric arc hazards, such as:

• Live electrical maintenance and repair workers
• Utility and power distribution personnel
• Industries where arc flash incidents are a documented thermal risk

By applying this standard, organizations can:

• Quantify the thermal protective performance of flame-resistant fabrics and clothing assemblies.
• Support risk assessment and hazard analysis related to electric arc exposure.
• Select appropriate arc-rated protective clothing based on ELIM, ATPV, or EBT values.
• Enhance worker safety by reducing burn injuries from electric arc incidents.

It is important to note that IEC 61482-1-1:2019 is complementary to IEC 61482-2, which covers the flame resistance properties of materials, and IEC 61482-1-2, which defines arc classification using a constrained arc test method.

Related Standards

• IEC 61482-1-2: Specifies test methods using a constrained arc for classification of arc protection classes APC1 and APC2. It complements IEC 61482-1-1 by providing additional classification schemes based on different test setups.

• IEC 61482-2: Addresses the flame resistance and performance of materials subjected to electric arc hazards, covering aspects not included in the open arc test methods of IEC 61482-1-1.

• IEEE 1584: Guides in calculating arc flash incident energy and boundary values for safety practices, often used alongside IEC protective clothing standards to assess exposure risks.

• NFPA 70E: Provides safety guidelines for electrical safety in the workplace including requirements for personal protective equipment, referencing arc rating standards such as IEC 61482 series.

By integrating IEC 61482-1-1:2019 with these related standards, stakeholders can develop a holistic electric arc hazard mitigation strategy with validated protective clothing performance, tailored to specific workplace risk profiles.

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Keywords: IEC 61482-1-1, protective clothing, electric arc, thermal hazards, arc rating, ELIM, ATPV, EBT, open arc testing, flame resistant clothing, arc flash protection, electrical safety standards, live working PPE

Standards Content (Sample)

IEC 61482-1-1 ®
Edition 2.0 2019-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Live working – Protective clothing against the thermal hazards of an electric arc –
Part 1-1: Test methods – Method 1: Determination of the arc rating (ELIM, ATPV
and/or EBT) of clothing materials and of protective clothing using an open arc

Travaux sous tension – Vêtements de protection contre les dangers thermiques
d’un arc électrique –
Partie 1-1: Méthodes d’essai – Méthode 1: Détermination de la valeur assignée
d’arc (ELIM, ATPV et/ou EBT) des matériaux pour vêtements et des vêtements de
protection utilisant un arc ouvert
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IEC 61482-1-1 ®
Edition 2.0 2019-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Live working – Protective clothing against the thermal hazards of an electric arc –

Part 1-1: Test methods – Method 1: Determination of the arc rating (ELIM, ATPV

and/or EBT) of clothing materials and of protective clothing using an open arc

Travaux sous tension – Vêtements de protection contre les dangers thermiques

d’un arc électrique –
Partie 1-1: Méthodes d’essai – Méthode 1: Détermination de la valeur assignée

d’arc (ELIM, ATPV et/ou EBT) des matériaux pour vêtements et des vêtements de

protection utilisant un arc ouvert

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 13.220.40; 29.260.99 ISBN 978-2-8322-6921-3

– 2 – IEC 61482-1-1:2019 © IEC 2019
CONTENTS
FOREWORD . 5
1 Scope . 7
2 Normative references . 7
3 Terms, definitions, symbols and units . 8
3.1 Terms and definitions . 8
3.2 Symbols and units. 13
4 Principle of test procedures A and B . 13
4.1 Procedure A – Material open arc test procedure . 13
4.2 Procedure B – Garment open arc test procedure. 14
5 Significance and use of the test procedures A and B . 14
5.1 General . 14
5.2 Procedure A – Material open arc test procedure . 15
5.3 Procedure B – Garment open arc test procedure. 15
6 Test apparatus . 15
6.1 General . 15
6.2 Calorimetric sensors . 15
6.2.1 Calorimeter construction . 15
6.2.2 Panel sensor construction. 17
6.2.3 Monitor sensor construction and positioning . 19
6.3 Panel construction . 20
6.4 Mannequin construction . 22
6.5 Arrangement of panels and monitor sensors for testing according to
Procedure A . 23
6.6 Arrangement of mannequin(s) and monitor sensors for testing according to
Procedure B . 24
6.7 Supply bus and electrodes . 28
6.7.1 General . 28
6.7.2 Structural cage arrangement . 28
6.7.3 Electrodes . 30
6.7.4 Fuse wire . 30
6.8 Electric supply . 30
6.9 Test-circuit control . 31
6.10 Data acquisition and data processing system . 31
6.10.1 General . 31
6.10.2 Data acquisition . 31
6.10.3 Signal synchronization . 32
7 Operator safety . 32
8 Specimen preparation . 33
8.1 Description of the test specimens . 33
8.1.1 Test specimens for Procedure A . 33
8.1.2 Test specimens for Procedure B . 33
8.2 Pre-treatment of test specimens by cleaning . 34
8.3 Pre-conditioning of the test specimens . 34
9 Calibration and verification . 34
9.1 Data acquisition system pre-calibration . 34
9.2 Verification of calorimeters . 34

9.3 Arc exposure and apparatus verification for the two-sensor panels and the
monitoring sensors. 35
9.3.1 Set-up of electrodes and fuse wire . 35
9.3.2 Positioning of the two-sensor panels, mannequins and monitor sensors . 35
9.3.3 Verification bare shot . 35
9.3.4 Verification bare shot test protocol . 36
10 Test apparatus care and maintenance . 36
10.1 Surface reconditioning . 36
10.2 Care of panels, mannequins and sensors . 37
10.3 Care of electrodes . 37
11 Test procedures . 37
11.1 Procedure A – testing with panels . 37
11.1.1 Test parameter and settings . 37
11.1.2 Sequence of tests with test specimens of material or material assembly . 37
11.1.3 Criteria for set of data obtained from iterative process of test shots . 38
11.2 Procedure B – testing with mannequins . 39
11.2.1 Test parameters and settings . 39
11.2.2 Single test or sequence of tests with test specimen(s) of garment or
garment assembly . 39
11.3 Air ventilation and initial temperature of sensors . 40
11.4 Specimen mounting . 40
11.4.1 Procedure A – testing with panels . 40
11.4.2 Procedure B – testing with mannequins . 40
11.5 Specimen description . 42
11.6 Test protocol . 42
12 Test results . 43
12.1 Heat calculation . 43
12.1.1 General . 43
12.1.2 Copper heat capacity . 43
12.1.3 Incident and transmitted energy . 43
12.1.4 Panel sensor response (transmitted energy (E ) comparison with Stoll
t
curve) . 44
12.1.5 Monitor sensor responses (incident energy (E )) . 45
i
12.2 Determination of arc thermal performance value (ATPV) . 46
12.3 Determination of breakopen threshold energy (EBT) . 46
12.4 Determination of the incident energy limit (ELIM) . 47
12.5 Visual inspection . 47
12.6 Arc rating . 49
12.6.1 Arc rating of a material or material assembly . 49
12.6.2 Arc rating of a garment or garment assembly . 49
13 Test report . 50
13.1 Reporting requirements common for tests according to Procedures A and B . 50
13.2 Reporting requirements specific for tests according to Procedure A . 51
13.3 Reporting requirements specific for tests according to Procedure B . 52
Annex A (informative) Logistic regression technique . 54
Annex B (informative) 95 % confidence intervals of ATPV and EBT . 56
Annex C (informative) Iterative process of test shots of Procedure A . 60
Annex D (informative) Example materials for insulating and mounting boards . 61

– 4 – IEC 61482-1-1:2019 © IEC 2019
D.1 General . 61
D.2 Materials for use as thermally insulating mounting board (6.2) . 61
D.3 Materials for use as mounting board, but not sufficiently thermally insulating
for use as insulating board (6.3) . 62
Annex E (informative) Recommended provisions for use of the test method for

accident replication and for research . 63
Bibliography . 64

Figure 1 – Example of calorimeter construction . 17
Figure 2 – Example of the panel sensor construction . 18
Figure 3 – Example of monitor sensor construction, with optional cover plate . 19
Figure 4 – Panel . 21
Figure 5 – Example of material clamping assembly of a panel . 22
Figure 6 – Arrangement of three two-sensor panels with monitoring sensors (top view)
for testing according to Procedure A . 24
Figure 7 – Relative positioning of arc electrodes and of mannequin(s) and monitor
sensors for testing according to Procedure B . 25
Figure 8 – Examples of mannequin configuration . 27
Figure 9 – Example of cage arrangement (supply bus, bus tubes and arc electrodes)
shown together with three panels for testing according to Procedure A (monitor
sensors are not shown) . 29
Figure 10 – Relative positioning of cage arrangement (supply bus, bus tubes and arc
electrodes) and of one torso mannequin and its monitor sensors for testing according

to Procedure B . 30
Figure 11 – Typical average transmitted energy curves Q (i.e. average response
t,avg
of the two sensors of same panel) for test specimens . 45
Figure B.1 – Probability density function (PDF) . 56
Figure B.2 – Cumulative density (CDF) . 57
Figure B.3 – Graph with probability, lower and upper limits . 59

Table 1 – Positioning of monitor sensors depending on incident energy exposure . 20
Table 2 – Reporting requirements and rating of visual inspection performance in case
of testing clothing material(s) according to Procedure A and garment(s) or an

assembly of garments according to Procedure B . 47
Table 3 – Visual assessment criteria in case of testing garment(s) or a garment
assembly according to Procedure B . 50
Table B.1 – Example of incident energy X and binary response Y (fulfillment of Stoll
criteria) for 21 test shots . 58

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LIVE WORKING –
PROTECTIVE CLOTHING AGAINST
THE THERMAL HAZARDS OF AN ELECTRIC ARC –

Part 1-1: Test methods –
Method 1: Determination of the arc rating (ELIM, ATPV and/or EBT)
of clothing materials and of protective clothing using an open arc

FOREWORD
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International Standard IEC 61482-1-1 has been prepared by IEC technical committee 78: Live
working.
This second edition cancels and replaces the first edition published in 2009. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
– addition of the Incident energy limit (ELIM) as a further arc rating performance property
value;
– replacement of char length requirement in the scope by indication that Procedure A is
applicable for testing of materials meeting the limited flame spread requirements of
IEC 61482-2;
– 6 – IEC 61482-1-1:2019 © IEC 2019
– clarification of the definition and the meaning of the Stoll curve;
– modification of specification of positioning of monitor sensors with respect to the electric arc
as function of intended high incident energy exposure of test specimens;
– modification of specifications of monitor sensor construction;
– specification of black paint;
– elimination of calorimeters from the chest of the mannequin;
– specification for possible positioning of mannequin(s) at a height different from the centre
of the electric arc and possible turning in order to adequately expose all parts of the garment
or clothing which would affect performance;
– more explicit description of requirements for data acquisition system;
– preconditioning of the samples;
– modification of requirements for apparatus and arc exposure verification by bare shots;
– more explicit description of test procedures A and B, in particular the subclauses dealing
with “sequence of test”, “test parameter” and “test criteria”;
– addition of determination of arc rating values of garments and/or garment assemblies.
The text of this International Standard is based on the following documents:
FDIS Report on voting
78/1256/FDIS 78/1262/RVD
Full information on the voting for the approval of this International Standard can be found in the
report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
In this standard terms defined in Clause 3 appear in italics.
A list of all parts in the IEC 61482 series, published under the general title Live working –
Protective clothing against the thermal hazards of an electric arc, can be found on the IEC
website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.

LIVE WORKING –
PROTECTIVE CLOTHING AGAINST
THE THERMAL HAZARDS OF AN ELECTRIC ARC –

Part 1-1: Test methods –
Method 1: Determination of the arc rating (ELIM, ATPV and/or EBT)
of clothing materials and of protective clothing using an open arc

1 Scope
This part of IEC 61482 specifies test method procedures to determine the arc rating of flame
resistant clothing materials and garments or assemblies of garments intended for use in clothing
for workers if there is an electric arc hazard.
An open arc under controlled laboratory conditions is used to determine the values of ELIM,
ATPV or EBT of materials, garments or assemblies of garments.
NOTE 1 The user can, if he desires, classify the arc protective performance into arc rating protection levels based
on ELIM, ATPV and/or EBT values which correspond best to the different hazard and risks levels that can result from
the user’s risk analysis.
NOTE 2 This document is not dedicated to classifying the arc protective performance of the material and clothing
into arc protection classes. Procedures determining these arc protection classes APC1 and APC2 are specified in
IEC 61482-1-2, which uses a constrained arc for testing.
NOTE 3 This test method is not intended and not appropriate to evaluate whether materials or garments are flame
resistant or not, as this is covered in IEC 61482-2.
Other effects than the thermal effects of an electric arc like noise, light emissions, pressure
rise, hot oil, electric shock, the consequences of physical and mental shock or toxic influences
are not covered by this document.
Protective clothing for work intentionally using an electric arc, e.g. arc welding, plasma torch,
is not covered by this document.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60584-1, Thermocouples – Part 1: EMF specifications and tolerances
IEC 61482-2:2018, Live working – Protective clothing against the thermal hazards of an electric
arc – Part 2: Requirements
ISO/IEC 17025:2017, General requirements for the competence of testing and calibration
laboratories
ISO/TR 11610, Protective clothing – Vocabulary
ISO 11612:2015, Protective clothing – Clothing to protect against heat and flame – Minimum
performance requirements
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3 Terms, definitions, symbols and units
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/TR 11610 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1.1
ablation
material response evidenced by formation of one or more openings in one
or several outer layers, but not in all layers of a material assembly specimen
Note 1 to entry: for the use of this document the opening is defined as follows:
a) with an opening in the layer of at least 1 600 mm in area or at least 80 mm in any planar direction,
b) with one or several individual threads across an opening not reducing the size of the opening.
3.1.2
arc duration
time duration of the arc
Note 1 to entry: Arc duration is expressed in milliseconds (ms).
3.1.3
arc energy
W
arc
electrical energy supplied to the arc and converted in the arc
Note 1 to entry: Arc energy is calculated as the sum of the instantaneous arc voltage values multiplied by the
instantaneous arc current values multiplied by the incremental time values during the arc duration.
Note 2 to entry: Arc energy is expressed in kilojoules (kJ).
3.1.4
arc gap
distance between the arc electrodes
Note 1 to entry: Arc gap is expressed in millimetres (mm).
3.1.5
arc rating
numerical value attributed to a product, that describes its protective
performance when tested in accordance with the open arc test
Note 1 to entry: The arc rating can be the arc thermal performance value (ATPV), the breakopen threshold energy
(EBT) or the incident energy limit (ELIM).
2 2
Note 2 to entry: The arc rating values are expressed in kJ/m (cal/cm ).
3.1.6
arc thermal performance value
ATPV
numerical value of incident energy attributed to a product that describes
its thermal properties of attenuating (reducing) a heat flux generated by an electric arc

Note 1 to entry: The ATPV of a material or material assembly is calculated using logistic regression analysis applied
to the data points obtained from testing a set of test specimens. It is the value of incident energy at which the heat
transfer through the test specimens is enough to reach the Stoll criteria with 50 % probability.
Note 2 to entry: The ATPV attributed to a garment or garment assembly is either equal to or lower than the ATPV of
the material or material assembly of which it is made, depending on whether the tested specimen(s) fulfil also
additional visual design and performance assessment criteria.
3.1.7
arc voltage
voltage across the arc
Note 1 to entry: Arc voltage is expressed in volts (V).
3.1.8
bare shot
electric arc event during which panels or mannequins are bare, i.e. they
are not covered by test specimens
3.1.9
breakopen
material response evidenced by the formation of an opening in the
material specimen
Note 1 to entry: For the use of this document the opening is defined as follows:
a) with a size of at least 300 mm in area or at least 25 mm in any planar direction,
b) with one or several individual threads across an opening not reducing the size of the opening.
Note 2 to entry: A material assembly specimen is considered to exhibit breakopen when all layers show formation
of one or more openings.
Note 3 to entry: Shrink-open is considered as a particular form of breakopen.
3.1.10
breakopen threshold energy
EBT
numerical value of incident energy attributed to product (material or
clothing) that describes its breakopen properties when exposed to heat energy generated by
an electric arc
Note 1 to entry: The EBT of a material or material assembly is calculated using logistic regression analysis applied
to the data points obtained from testing a set of test specimens. It is the value of incident energy at which breakopen
occurs with 50 % probability.
Note 2 to entry: The EBT attributed to a garment or garment assembly is either equal to or lower than the EBT of
the material or material assembly of which it is made, depending on whether the tested specimen(s) fulfil also
additional visual design and performance assessment criteria.
3.1.11
burning time
afterflame time
time for which a flaming of the test specimen is visible after the end of the electric arc duration
Note 1 to entry: Burning time is expressed in seconds (s).
3.1.12
calorimeter
assembly of a copper disc with attached thermocouple, used for measuring the heat energy and
incident energy
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3.1.13
calorimetric sensor
sensor
assembly of a calorimeter and a non-conductive heat resistant material, in which the calorimeter
is mounted
Note 1 to entry: The term sensor is used in this document to mean calorimetric sensor.
3.1.14
charring
material response evidenced by formation of carbonaceous residue as the result of pyrolysis or
incomplete combustion
3.1.15
dripping
material response evidenced by formation of polymer droplets that fall from the material or
garment
3.1.16
electric arc
self-maintained gas conduction for which most of the charge carriers are electrons supplied by
primary-electron emission
Note 1 to entry: During live working, the electric arc is generated by gas ionization arising from an unintentional
electrical conducting connection or breakdown between live parts or a live part and the earth path of an electrical
installation or an electrical device. During testing, the electric arc is initiated by the blowing of a fuse wire.
[SOURCE: IEC 60050-121:1998, 121-13-12, modified – Note 1 to entry has been added to refer
specifically to live working and arc testing.]
3.1.17
embrittlement
formation of a brittle residue as the result of pyrolysis or incomplete combustion
3.1.18
flame resistant
property evidenced by clothing materials which meet the limited flame
spread requirements of IEC 61482-2
3.1.19
garment
single item of clothing which may consist of single or multiple layers of materials
3.1.20
garment assembly
assembly of garments
clothing consisting of two or more garments worn together, which may individually cover
different parts of the wearer’s body and/or which may be worn fully or partially on top of each
other
Note 1 to entry: For example, garment assembly can be a combination of jacket and trousers, combination of shirt,
trousers and jacket or overcoat which have been designed in such a way as to fit together.
3.1.21
heat flux
q
thermal intensity transmitted by an electric arc indicated by the amount of
heat energy transfer per unit surface area and time

3.1.22
ignition
initiation of flaming and combustion
3.1.23
incident energy
E
i
heat energy Q resulting from an electric arc, received at a unit surface
area at a specified distance from the electric arc
3.1.24
incident energy limit
ELIM
numerical value of incident energy attributed to a product (material or
clothing), below which value all product responses are below the Stoll curve and without
breakopen
Note 1 to entry: The ELIM of a material or material assembly is calculated from data points obtained from testing a
set of test specimens, which are also used for the determination of the ATPV and/or EBT.
Note 2 to entry: The ELIM attributed to a garment or garment assembly is either equal to or lower than the ELIM of
the material or material assembly of which it is made, depending on whether the tested specimen(s) fulfil also
additional visual design and performance assessment criteria.
3.1.25
material
substances, excluding hardware, of which an item of clothing is made
3.1.26
material assembly
assembly of materials, which is representative for the build-up of layers of a garment or garment
assembly
Note 1 to entry: The arc rating of a material assembly of which an assembly of garments worn on top of each other
is made, cannot be determined from the arc rating of each material, of which the individual garments are made but
can only be determined by testing of material assembly specimens representative for the garment assembly.
3.1.27
material response
reaction of the material to an electric arc characterised by ignition, burning time (afterflame
time), breakopen, melting, dripping, shrinkage, etc.
3.1.28
melting
material response evidenced by softening and deformation
Note 1 to entry: Materials which melt are normally polymers.
3.1.29
mix zone
range of measured incident energies (the independent variable X), in
which a binary response (i.e. either the value “0” or “1”) (the dependent variable Y) is attributed
to a studied parameter of the measured material response or to a combination of several studied
parameters
Note 1 to entry: A mix zone of a data point distribution is established when the highest incident energy with binary
response “0” is greater than the lowest incident energy with binary response “1”. The mix zone of a data point
distribution is empty when the highest incident energy with a binary response “0” is lower than the lowest incident
energy with a binary response “1”.
Note 2 to entry: For the material response parameters studied for the determination of the ATPV, see 11.1.3.1
and 12.2.
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Note 3 to entry: For the material response parameters studied for the determination of the EBT, see 11.1.3.2
and 12.3.
Note 4 to entry: For the material response parameters studied for the determination of the ELIM, see 11.1.3.3
and 12.4.
3.1.30
monitor sensor
calorimetric sensor mounted on each side of the panel or mannequin, not
covered by a test specimen and used to measure incident energy at a specified distance from
the electric arc
3.1.31
open arc
electric arc between two vertically opposing electrodes intended to
provide an equal distribution of emitted energy around the centreline formed by the electrodes
and where the emitted energy is not directed by means of any physical constraints (e.g.
enclosure, wall)
[SOURCE: IEC 61482-2:2018, 3.1.13]
3.1.32
panel sensor
calorimetric sensor mounted in the panel, which, when covered by test
specimen, is used to measure energy transmitted through a test specimen
3.1.33
protective clothing
clothing which covers or replaces personal clothing, and which is designed to provide protection
against one or more hazards
[SOURCE: ISO 13688:2013, 3.5, modified – The definition has been modified to clarify by
removing the unclear term “protector”.]
3.1.34
shrinkage
material response evidenced by reduction in specimen size
3.1.35
shrink-open
material response caused by excessive shrinkage with the result that the
test specimen dislodging from the clamping and exposing the panel
Note 1 to entry: Shrink-open is considered as a particular form of breakopen.
3.1.36
Stoll curve
empirical predicted second-degree skin burn-injury model
Note 1 to entry: Stoll curve defines a relationship between the absorbed energy rate and the human skin tolerance
time.
Note 2 to entry: See Stoll, A.M. and Chianta. M.A. Method and rating system for evaluation of thermal protection.
3.1.37
test shot
electric arc event during which one or more test specimens are mounted
on the specimen support(s) of the test apparatus, with the specimen(s) covering some or all
sensors except monitor sensors and being exposed to the effects of the electric arc

3.1.38
X/R ratio
ratio of system inductive reactance to resistance
Note 1 to entry: The X/R ratio is proportional to the L/R ratio of time constant, and is, therefore, indicative of the
rate of decay of any DC offset. A large X/R ratio corresponds to a large time constant and a slow rate of decay.
3.2 Symbols and units
2 2
ATPV arc thermal performance value
kJ/m (cal/cm )
C heat capacity J/g °C
p
2 2
EBT breakopen threshold energy
kJ/m (cal/cm )
E incident energy
kJ/m
i
E transmitted energy
kJ/m
t
2 2
ELIM incident energy limit
kJ/m (cal/cm )
Q heat energy
kJ/m
q heat flux
kW/m
T temperature K
t time s
t arc initiation time s
NOTE
2 2 2 2
1 kJ/m = 1 kW·s/m = 0,1 J/cm = 0,023 9006 cal/cm
2 2 2
1 cal/cm = 41,840 kJ/m = 41,840 kW·s/m .

4 Principle of test procedures A and B
4.1 Procedure A – Material open arc test procedure
Procedure A specified in this document is used to determine the arc rating of a material or
material assembly, expressed by the value of ATPV or EBT, whichever is the lower one, or
expressed by the value of the ELIM if specified by the person requesting testing, that the arc
rating shall be expressed by the ELIM. The ATPV, EBT and ELIM are determined by comparing
the amount of heat transmitted through the specimen(s) with Stoll criteria and the possible
observation of breakopen when exposed to various levels of incident energy measured by the
monit
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