What's New with Arc Flash Standards
2015-06-10 08:45 | writer: admin
The National Fire Protection Association (NFPA) 70E Standard for Electrical Safety in the Workplace has been around since 1979. The sections related to electric arc flash were introduced back in 2000. NFPA 70E is an important standard for protecting industrial electrical workers from the very dangerous affects of electric shock and arc flash. There have been many revisions, additions, and improvements related to arc flash safety over the years, and the 2012 edition is no exception. It includes a number of changes both to better clarify the intent of various sections and to provide additional protection measures. However, even changes that are intended to help clarify can often cause initial confusion, simply because they are changes. This article will review some of the changes that have raised questions and may need explanation.
The first change of note, and potentially the most confusing, was the replacement of the terms "flame-resistant" and "FR" with the term "arc rated." The purpose of this change was to eliminate the use of flame-resistant garments that use a type of fabric labeled as flame-resistant/FR that has not been arc tested and therefore does not have an arc rating. These fabrics have been tested for flame resistance using standards that have nothing to do with arc flash protection, but because they use the term FR, they have occasionally found their way into the market.
An example of a 70E section where FR was changed to arc rated is in section 130.7(C)(6), which previously read, "Body Protection. Employees shall wear FR clothing wherever there is a possible exposure to an electric arc flash...." The revised section in the 2012 edition reads, "Employees shall wear arc-rated clothing wherever there is a possible exposure to an electric arc flash...." This change forces the fabric to have been arc tested and the garment to be labeled with an arc rating shown as either the Arc Thermal Performance Value (ATPV) or Energy of Breakopen Threshold (EBT). The confusion comes in when users do not see the term arc rated on the garment. In the end, an FR garment that has an established arc rating shown on its label meets the new requirement. The standard does not require the use of the term arc rated; it simply requires there be an arc rating for the product. This is a pretty straightforward change, but someone reading it for the first time could naturally look for the words arc rated on a label.