Frequently Asked Questions
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 is the shelf life of an arc flash suit?
This is a challenging topic to consider as many variables must be considered when determining when an arc flash suit needs to be replaced. Things like the age of a suit, frequency of use, laundering care, and the environment your suit is stored in can all play roles in how long it will last. Oberon recommends a pre and post inspection after every use of your arc flash suit. The diagram below lists out some common things to look for when doing your evaluation.
In the end, the final determination on when to replace your suit should be a part of your established electrical safety program. Please contact your local Oberon Company representative if further assistance is needed.
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.
How do I size my workers for an arc flash suit?
Refer to Oberon’s Sizing Guide section of the website. Alternatively, an Oberon Representative can help arrange for an arc flash suit sizing kit to be provided for your workers to use. The proper garment size will ensure electrical workers are protected, comfortable and productive. Arc flash suit sizes should be selected to be loose fitting over top of the worker’s uniform or everyday clothing. When sharing arc flash suits be certain to ensure every possible electrical worker has a comfortable size available to wear.
Oberon arc flash suits are sold in alphabet sizes from Small up to 5XL. All Oberon garments are available in regular (standard height), tall, extra tall or short vertical measurements. The arc flash suit size must be adequate to completely cover the workers body, not showing the underlayers in any area.
Does Oberon offer a long coat type arc flash suit?
No, Oberon has been a strong advocate against the use of this type of arc flash suit for the past 20 years. Long Coat with leggings style arc flash suits are a protection concern for workers! If a worker doesn’t kneel or squat with their legs together a large opening is created at the bottom. Furthermore, thermal incident energy can deflect and chimney up inside the long coat. Arc flash suits should be a Hood with either a Coat & Bib-Overall or Coverall. If you have a long coat style arc flash suit it should be replaced.
I know the voltage, what arc flash suit should I get?
Voltage does dot determine the arc flash hazard. Knowing the voltage is only one piece of determining Arc Flash PPE. The electrode orientation, available fault current (amps), the working distance between the worker and the equipment, the clearing time of the circuit protection device, the spacing between conductors or from a conductor to ground, the number of phases, whether the conductors are in an enclosure, and the equipment configuration must all be considered when determining the potential severity of an arc flash hazard. NFPA 70E provides two methods for the selection of arc flash PPE as part of an overarching requirement to complete an arc flash risk assessment. The two selection methods are;
- Incident energy analysis method. Often referred to as an “arc flash study”, requires engineering calculations to determine the potential thermal incident energy in the event of an arc flash. Arc flash PPE is then selected so the arc rating (protection) matches or exceeds the calculated incident energy. Both the thermal incident energy and protective arc ratings are calculated as calories per square centimeter (cal/cm2).
- Arc flash PPE category method. Otherwise known as the “table method”, involves a simplified approach using the tables from within the Standard to determine a category number from 1-4 and corresponding arc flash PPE minimum requirements. The table method requires validation of the parameters used in the creation of the categories, otherwise the user is forced into using the incident energy analysis method. Refer to Oberon’s catalog on page #5 for arc flash PPE category product information.
Either, but not both, arc flash PPE selection methods can be used on the same piece of equipment. The engineering calculations used in the incident energy analysis method cannot be used to specify an arc flash PPE category. Keep both methods separate and document your decision making processes within your company’s Electrical Safety Program.
The bottom line is that you can’t rely on voltage alone to figure out what arc flash PPE you need. NFPA 70E requires the employer to complete an arc flash risk assessment. If additional protective measures are required, arc flash PPE can be applied as a control to mitigate the risk of an arc flash. Refer to the latest edition of the NFPA 70E Standard to learn more about the requirements for an arc flash risk assessment.
Are Oberon TCG™ fabrics lighter weight than fire resistant treated cotton?
Yes, absolutely. For example, an Oberon TCG40™ garment, which is constructed of Oberon’s proprietary Inherently/Permanently Flame Resistant (IFR) fabric (a fabric specifically designed for the Arc Flash marketplace) and which has an arc rating of 46 cal/cm2, has a fabric weight of 10.9 ounces per square yard. A comparable chemically flame retardant treated (FRT) cotton product, with a similar arc rating, would weigh nearly twice as much. Additionally, Inherently FR garment is less bulky and more comfortable to wear. Garments manufactured with Inherently Flame Resistant fabrics like Oberon TCG™ Series and its LAN™ Series are permanently flame resistant. Unlike some FRT cotton fabrics, you cannot impact the flame resistant characteristic with washing. Really, the only benefit to an FRT cotton product is the low price. For the infrequent user, an FRT cotton garment can be a good solution. But for the industrial electrician, who will be using the garments frequently, the superior comfort and durability offered by an Inherently Flame resistant garment makes it the preferred choice. Oberon does offer a low cost FRT Cotton product (CAT™ Series) in addition to our IFR products (Good-Better-Best).
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.