Thermal hazards due to electric fault arcing
Guide for selecting Personal protective equipment
(DGUV Information 203-077)
Information
DGUV Deutsche Gesetzliche Unfallversicherung Spitzenverband |
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Stand der Vorschrift: Juli 2021
Table of contents | Abschnitt |
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Preliminary remarks | |
Scope of application | 1 |
Definitions | 2 |
Performing the Risk Assessment | 3 |
Evaluation phases | 3.1 |
Case-by-case evaluation | 3.2 |
Procedures for selecting PPEaA | 4 |
Overview of the estimation process | 4.1 |
Estimation process for AC installations | 4.2 |
Work environment parameters | 4.2.1 |
Determination of system electric arc energy in the event of a fault | 4.2.2 |
Determining the PPEaA protection level for the work situation | 4.2.3 |
Selection of PPEaA | 4.2.4 |
Estimation process for DC installations | 4.3 |
General calculation methodology | 4.3.1 |
Rough estimation based on reference values (worst-case considerations) | 4.3.2 |
Hints for practical implementation | 5 |
Directives, Regulation, Literature | Annex 1 |
EU Directives and Regulations | A 1.1 |
Provisions, Rules and Information for occupational safety and health | A 1.2 |
Standards/VDE provisions | A 1.3 |
Literature | A 1.4 |
Standardization of PPEaA against the thermal effects of electric fault arcing | Annex 2 |
Standardization for protective clothing | A 2.1 |
Standards originating in Europe for testing protective clothing | A 2.2 |
Standards originating in America for testing protective clothing | A 2.3 |
Standardization for other types of PPEaA | A 2.4 |
Standards originating in Europe | A 2.4.1 |
Standards originating outside the EU | A 2.4.2 |
Requirements for proper selection | A 2.5 |
Parameters and risk analysis of thermal hazards to persons due to electric arcing | Annex 3 |
General Preliminary remarks | A 3.1 |
Energetic parameters for thermal hazards to persons due to electric arcing | A 3.2 |
Methods for determining Warc and Warc, prot | A 3.3 |
Work steps | A 3.4 |
Ascertain the general operating conditions | A 3.4.1 |
Calculate the short-circuit currents at the work places under study | A 3.4.2 |
Determine the short-circuit duration (arc duration) | A 3.4.3 |
Determine the expected value of electric arc energy | A 3.4.4 |
Determine the working distance | A 3.4.5 |
Determine the Arc protection level of the PPEaA | A 3.4.6 |
Consider the divergent exposure relationships | A 3.4.7 |
Using the analysis results for the Risk assessment | A 3.4.8 |
Alternative test methods | A 3.5 |
Application of the Risk matrix | Annex 4 |
General | A 4.1 |
Evaluation of the anticipated severity of injury | A 4.2 |
Evaluation of the probability of occurrence | A 4.3 |
Examples | Annex 5 |
Example 5.1: Low voltage distribution in a transformer station (Work location 1) | A 5.1 |
Example 5.2: Low voltage cable (Work location 2) | A 5.2 |
Example 5.3: House junction box (Work location 3) | A 5.3 |
Example 5.4: Electrical installation behind the house junction box (Work location 4) | A 5.4 |
Example 5.5: Removal of NH fuse-links | A 5.5 |
Example 5.6: Industrial distributor | A 5.6 |
Example 5.7: Switching on systems of older design, not tested for electric fault arcing | A 5.7 |
Example 5.8: Working on DC installations (UPS) | A 5.8 |
Working in the vicinity of a battery or directly on the battery cells (Work location 1) | A 5.8.1 |
Working in the vicinity of the inverter (DC intermediate circuit, Work location 2) | A 5.8.2 |
Example 5.9: Working on DC installations (traction network)) | A 5.9 |
Exemplary work locations for determining transmission factor kT | Annex 6 |
Coordination of PPEaA and pre-fuses | Annex 7 |
Practical rules of application for the coordinated selection of PPEaA and backup fuse | A 7.1 |
Selection matrix | A 7.2 |
Line protection fuses | A 7.3 |
Transformer protection fuses | A 7.4 |
Safe-work fuses | A 7.5 |
Minimum overcurrent factor | A 7.6 |
Permissible fuse trip times | A 7.7 |
Selection guide worksheets | Annex 8 |
Preliminary remarks
This DGUV Information brochure is intended to support employers in their selection of suitable personal protective equipment (e.g. protective clothing, head and face protection and gloves) against the thermal effects of an electric fault arc (PPEaA).
Persons working on or in the vicinity of live electrical equipment are, in principle, exposed to hazards associated with electric fault arcing. Electric arcs are rare, yet cannot be eliminated completely in the working environment, meaning that persons therein will require reliable protection. Arcing is not only induced by short circuiting, but can also occur when two current-carrying components are separated from each other (e.g. installation/removal of circuit protectors while under load).
The T-O-P principle for occupational safety should be used when evaluating thermal hazards and determining the measures to apply against electric fault arcing. This means that the use of personal measures (PPEaA) is viewed as being subordinate to technical and organizational measures. PPEaA is intended to minimize the remaining residual risk after the technical and organizational measures aimed at preventing an electric arc occurrence have been implemented. |
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Depending on the electrical network and equipment configuration, electric arcing can be extremely hazardous:
High levels of thermal energy.
Shock waves and associated fragments released by the explosive propagation of an arc flash.
High intensity electromagnetic radiation, particularly in the ultraviolet (UV) and infrared (IR) radiation bands, but also in the visible light band, which can lead to irreversible damage to the eyes and skin.
High levels of acoustic shock (blast).
Toxic gases and particles produced by melting and vaporized materials in the vicinity of the arc flash (including electrodes)
Each consequence can, by itself, endanger the health and even the life of a person in proximity of the occurrence.
The most serious personal risks are associated with the thermal effects of electric fault arcing.
The PPEaA selection process used in this DGUV Information is based on the standardized Box test method according to DIN EN 61482-1-2 (VDE 0682-306-1-2) [11].
Note |
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The procedures related to the selection of PPEaA tested in accordance with DIN EN 61482-1-1 (VDE 0682-306-1-1) [10] have already been described in NFPA 70E [14] and IEEE 1584-2018 [15]. For this reason, they are not addressed in this DGUV Information. |
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Furthermore, an overview of the PPEaA selection process is included in the ISSA (International Social Security Association) "Guideline for the selection of personal protective equipment when exposed to the thermal effects of an electric fault arc" (2nd edition 2011) [26]. |
It is recommended to perform a Risk assessment in order to evaluate the hazards associated with electric fault arcing and to facilitate subsequent PPEaA selection. In addition to the potential severity of damage, the probability of injury due to electric arcing should also be considered as part of the analysis. Section 3 of this DGUV Information describes the approaches that can be taken with respect to the thermal effects of electric arcing.
Comprehensive examples in Annex 5 as well as exemplary depictions of work locations in Annex 6 support those who apply this DGUV Information with implementation of the Risk assessment and with the calculation process. Practical rules to apply when coordinating the selection of PPEaA with pre-fused circuits (Annex 7) point the way to finding suitable PPEaA based on the fuses used or selected.