What are the limitations of an arc flash rated suit?

A common misperception is that a person wearing an arc rated suit is “bullet proof” from the hazards associated with electricity. There are 3 main potential hazards when working with electricity: Electric Shock, Arc Flash and Arc Blast. An arc flash suit can protect you from an arc flash provided that the incident energy level that the suit is exposed to is equal to or less than what the suit is rated for.  All arc tested suits will come labeled with an estimated APTV level measured in calories/cm2.  Oberon recommends having a risk assessment done before working on any electrical equipment to help identify the possible risks associated with the work task to be performed.  Once this analysis is done the appropriate APTV level needed can be determined and the proper PPE selected.

This leaves two other potential electrical hazards that could potentially harm you.  The arc blast is high pressure sound wave that is caused by a sudden arc fault.  It can cause molten metal droplets to be propelled at high speeds as well as sudden expansion of air pressure that can blast out.  An arc flash suit offers some protection from these types hazards, but only in a limited capacity.  For instance, if a blast pressure wave were to be strong enough to propel a worker across a room an arc flash suit would not be able to protect the worker from the force of the wave.

The last type of electrical hazard that a worker can be exposed to is electrical shock.  Shocks are caused when contact is made by a worker with an electrical energy source.  Arc flash suits are not tested or designed to protect workers from this type of hazard.  Typically workers will wear rubber electrical gloves with leather protectors when there is a risk of electrical shock while performing their work task.

What fabric is the best for arc flash clothing?

There are three different types of arc-rated flame resistant (FR) fabrics available on the market; Treated non-inherently FR fabrics, Inherently FR fabrics and Treated Inherently FR fabrics. Treated non-inherently FR fabrics, either 100% cotton, or cotton blends, have no flame resistant properties and require a chemical treatment application to become flame resistant (FRT). Inherent fabrics are engineered to be flame resistant (IFR), and there is no chemical that needs to be added to them for their protective capabilities. Treated Inherently FR fabrics are when traditional Inherently FR fabrics are treated using a similar process to non-inherently FR fabrics, resulting in a lightweight inherently FR fabric that provides more protection. Regardless of the type of FR fabric, the material must still be arc-rated with either an Arc Thermal Performance Value (ATPV) or an Energy Break-open Threshold (EBT).

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.

How do I pre-use inspect my arc flash suit?

The NFPA 70E Standard requires that all arc flash PPE is pre-use inspected. Refer to Oberon’s resource section of the website for literature resources including User Guides and Storage, Use, Care & Maintenance files. While inspecting your arc flash suit if you identify a problem do not use the product until the issue has been repaired, cleaned or replaced. When pre-use inspecting your Oberon arc flash suit you should inspect each item one at a time.

Can Arc Flash PPE be shared between workers?

No, due to personal hygiene and the risk of spreading infectious disease. Please see our white paper in the resource section of our website for more details. In summary, hard non-porous surfaces can be effectively disinfected, such as the arc flash hood visor, hard hat and other plastic components. However, we do not believe that fabrics can be safely shared between workers due to the ineffectiveness of disinfectant sprays or wipes on a porous surface. In the new Coronavirus world, we feel the most effective way to keep workers safe and healthy is for all arc flash PPE to be individually assigned.