How do the arc-rated clothes actually protect me?
Arc Flash PPE is tested to determine its protective ability, this is called an arc rating. This testing is done on the fabric or a finished product using various different testing methods according to applicable Standards. Arc-rated clothing provides insulation that protects a worker from the thermal incident energy caused by an arc flash incident.
There are various different types of arc ratings. In North America, the most popular product options have an ATPV or EBT rating. An arc rating is reported as either ATPV or EBT, whichever is the lower value. The ELIM is a new way to evaluate the arc thermal resistance properties to select PPE with a lower risk of a worker skin burn injury. All of these values are provided in calories per square centimeter (cal/cm2).
ATPV: Arc Thermal Performance Value, the incident energy level at which there is a 50% probability of sufficient heat transfer to cause the onset of a second-degree skin burn injury.
EBT: Break-open Threshold Energy, the incident energy level at which there is a 50% probability of the formation of holes or tears in the layer closest to the skin.
ELIM: Incident Energy Limit, the highest incident energy data point without breakopen and without reaching the onset of a second-degree skin burn injury
The most common type of arc rating is the Arc Thermal Performance Value, or ATPV. Selecting PPE with an arc rating that matches or exceeds the highest level of potential thermal incident energy exposure from an arc flash incident, is critical in protecting your electrical workers. It is critical to know the incident energy potential of the equipment in your electrical environment to effectively choose the correct Arc-Rated PPE with the appropriate arc-rating.
