Arc flash

Proper arc-rated clothing

I work in a hot environment, and the protective arc-rated clothing required increases discomfort and fatigue. Are there certain choices in arc-rated clothing available that are cooler and more comfortable?

Responding is James Cliver, senior FR technologist & development engineer, Milliken, Spartanburg, SC.

Protection and comfort is a balance when you are concerned about your safety. You should not compromise the level of protection you need. However, there are some things to look for in protective arc-rated clothing.First, within the given arc-rating category required for your job safety, the weight of the fabric in the garment and hence the weight you carry around all day can affect your level of fatigue. Look for the lightest weight fabric with the protection level you need. Also, within each arc-rating category, the breathability of different fabrics varies widely. This can be measured by a standard test called “air permeability,” and your clothing supplier may already test for this, so ask about it. A fabric with higher air permeability can more easily move air through the garment, exchanging the warm, moist air around your skin with the outside air, keeping you cooler and more comfortable.

Our employees wear arc-rated clothing required for the hazards of their job. How does what they wear under their arc-rated personal protective equipment affect their protection level?

Responding is James Cliver, senior FR technologist & development engineer, Milliken, Spartanburg, SC.

First, you need to be aware that as you perform different tasks, the level of the arc flash hazard may change and the Hazard Risk Category of your arc-rated clothing must be appropriate for each task. This may require adding additional PPE. Often, people assume that extra clothing layers such as undergarments provide additional protection, and that may be the case. However, you should know if your under layers are flame-resistant, non-FR or made from fibers that melt when exposed to heat. If the layer you wear under your arc-rated clothing also is arc-rated, it can be used to increase the arc rating of the system and provide additional protection. If the under layer is a non-FR, non-melting fabric, it cannot be used to increase the arc rating, so it is important to know that the outer layer has the correct HRC level for the task. Also, the possibility of ignition of the under layer exists, which could increase the severity of skin burn in an arc flash event. A synthetic fabric that melts when heated, such as polyester or nylon, can decrease the protection to the wearer in an arc flash event, as it can melt and shrink onto the skin even if the outer protective layer is not breached.

Editor’s Note: These articles represent the independent views of the authors and should not be construed as National Safety Council endorsements.

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