A Comprehensive Analysis of the Influence of Thermal Insulating Materials on Arc Rating Tests

The arc rating (AR) characterization process is a crucial step before conducting arc flash personal protective equipment (PPE) performance tests. Over the past decades, a substantial number of arc-rated fabrics used in arc-protective garments have been tested. Despite the positive impact of laboratory-tested arc-resistant PPE on worker safety, there is still ongoing investigation regarding the influence of various factors by laboratories and manufacturers with the highest expertise worldwide. This important issue pertains to the precise determination of the AR of materials, which directly affects PPE selection and usage procedures. Although standardized methods for determining ARs exist, significant variations have been observed when tested in different, or even the same, laboratories. Among the numerous requirements for arrangements and setups, one of the most relevant factors influencing test performance is the thermal insulation material used in calorimeter construction, as specified by international standards. Unfortunately, no previous study or technical foundation for the use of actual materials is available, even in the ASTM or IEC standards’ references. The scarcity of certain insulating materials in South America and Europe prompted a study on their actual influence on AR tests. This study consists of an innovative and brand-new investigation of the influence of thermal insulating materials characteristics on AR test results. Two periods of fabric AR tests were investigated, resulting in 207 valid results. From 2016 to 2020, 123 tests were conducted using Marinite P insulating boards, while from 2020 to 2022, 84 tests were conducted using Marinite A. Numerical simulations and analytical calculations were performed to corroborate the results. No significant variations were found between the materials used in these periods. However, test variations of up to 37% were observed in a global analysis, which aligns with current published results.