Arc Flash PPE Category - Safety Compliance Explained

By R.W. Hurst, The Electricity Forum

Arc Flash PPE Category

Electrical explosions pose a significant risk to electrical workers, and proper personal protective equipment (PPE) is essential to safeguard them from these hazards. This article delves into the categories of arc flash PPE, detailing the types of protective gear required, and answering key questions about arc flash PPE categories, including how to determine them, the necessary PPE for each category, and specific requirements for various categories.

Understanding the arc flash ppe category is crucial for ensuring the safety of electrical workers. By conducting a thorough risk assessment and selecting the appropriate PPE based on the incident energy levels, employers can significantly reduce the risk of injury from electrical explosions. From Category 1, with its minimum arc rating of 4 cal/cm², to Category 4, requiring a minimum arc rating of 40 cal/cm², each level of protection is designed to address specific hazards and provide the necessary safeguards for those working in potentially dangerous environments. Investing in the right arc-rated PPE is not just about compliance; it's about protecting lives and ensuring that every worker goes home safely.

How to Determine Arc Flash PPE Category?

Determining the appropriate arc flash PPE category involves assessing the incident energy levels present during potential electrical explosions. Incident energy is the amount of energy impressed on a surface, typically measured in calories per square centimeter (cal/cm²). The higher the incident energy, the more protective the PPE must be. The categories of arc flash PPE categories range from Category 1 to Category 4, each corresponding to a specific range of incident energy:

Category 1: Minimum arc rating of 4 cal/cm²
Category 2: Arc rating greater than 4 cal/cm² but less than 8 cal/cm²
Category 3: Arc rating greater than 8 cal/cm² but less than 25 cal/cm²
Category 4: Arc rating greater than 25 cal/cm² but less than 40 cal/cm²

To determine the PPE category, a comprehensive risk assessment must be conducted. This involves calculating the potential incident energy levels at various points in the electrical system and selecting PPE with an arc rating that meets or exceeds these levels.

What PPE is Used for Arc-Rated Category?

For each arc-rated category, specific PPE is required to ensure adequate protection against hazards. The PPE for each category includes:

Category 1: Requires a minimum arc rating of 4 cal/cm². This includes a long sleeve shirt and pants made of arc-rated fabric, rubber insulating gloves with leather protectors, and an arc face shield.
Category 2: Requires an arc rating greater than 4 cal/cm² but less than 8 cal/cm². This category typically includes an arc-rated flash suit jacket, long sleeve shirt and pants, rubber insulating gloves with leather protectors, and an arc face shield.
Category 3: Requires an arc rating greater than 8 cal/cm² but less than 25 cal/cm². PPE for this category includes an arc-rated flash suit jacket and pants, an suit hood, rubber insulating gloves with leather protectors, and additional arc-rated PPE as necessary.
Category 4: Requires a minimum arc rating of 40 cal/cm². This includes a complete arc-rated flash suit, consisting of a suit hood or AR face shield, a flash suit jacket and pants, rubber insulating gloves with leather protectors, and other protective equipment as needed.

Does a PPE Category 1 Require an Arc Shield?

Yes, PPE Category 1 does require an arc shield. Despite being the lowest category, it is still essential to protect the face and eyes from potential hazards. An arc face shield provides this protection, ensuring that the wearer is shielded from the thermal effects of electrical explosions. In addition to the arc face shield, Category 1 PPE includes a long sleeve shirt and pants with a minimum arc rating of 4 cal/cm², rubber insulating gloves with leather protectors, and other basic protective gear.

What is PPE Category 3?

PPE Category 3 is designed for environments where the incident energy is greater than 8 cal/cm² but less than 25 cal/cm². The PPE required for this category includes:

Arc-Rated Flash Suit Jacket and Pants: These garments provide a higher level of protection, with a minimum arc rating of 25 cal/cm².
AF Suit Hood or AR Face Shield: This equipment protects the head, face, and neck from the intense heat and light produced by an explosion.
Rubber Insulating Gloves with Leather Protectors: These gloves protect the hands from electrical shock and AF hazards.
Additional Arc-Rated PPE: Depending on the specific risks present, additional arc-rated PPE may be required to provide comprehensive protection.

Examples of PPE could include a hard hat, face shield, flame resistant neck protection, ear protectors, flame retardant (FR) suit, insulated rubber insulating gloves with leather protectors, and insulated leather footwear. Ar clothing must meet the requirements as shown in the latest edition of 70E. PPE, sufficient for protection against the potential electrical flash, is required for every part of the body. The selection of the required thermal arc rated ppe depends on the incident heat energy level at the point of work.

The common distance used for most of the low voltage incident energy measurement research and testing is at 18 inches from the arcing fault source. So what energy does a body part experience that is closer to the arc fault than 18 inches? The closer to the arcing fault, the higher the incident energy and blast hazard. This means that when the flash protection analysis results are calculated at 18 inches from the arc fault source, the incident energy and blast energy at the point of the arc fault are considerably greater. Said in another way, even if the body has sufficient PPE for an 18" working distance, severe injury can result for any part of the body closer than 18" to the source of the arc.

Advances in AF kits have definitely improved the arc-flash clothing options available to workers. It was not all that long ago – the 1980s – that the choice of flash protection was extremely limited, and few employers even had a policy on flash clothing. Today there are a dozen or so brand names of Arc Flash PPE, with some brands providing different fabrics ranging from five to 13 ounces per square yard fabric weight. These fabrics are available in an array of colors, weaves, and textures. As with all safety equipment, arc kit is of no use to anyone unless it is being used at the time of an electrical explosion.

Definitions Arc Thermal Performance Value (ATPV): This value is presented in calories per square centimeter and represents the maximum capability for arc-flash protection of a particular garment. This rating also applies to fabrics. However, a garment made from more than one layer of arc-flash-rated fabric will have calories per square centimetre rating greater than the sum of the ATPV ratings of the original fabrics. The calories per square centimeter rating of most arc-flash protective suits, coveralls, and coats is commonly sewn into the fabric in large letters on the outside of the garment. Flame Resistant (FR): “Flame resistant” can describe a fabric naturally resistant to burning but also can represent a material with special treatment applied to the fabric.

Occasionally, the letters FR are used to represent “flame retardant.” This can lead to some confusion because a flame-retardant treated fabric is flame resistant, but a flame-resistant fabric is not necessarily flame retardant. Flame Retardant: This term could be used to describe a fabric made up of a flammable fabric treated in such a way that it will provide arc-flash protection.

Fabric Weight: This is usually represented in one of two ways: ounces per square yard or grams per square meter. Both of these values essentially refer to the thickness of the fabric. The more ounces per square yard, the more material exists in the same square yard of fabric.

Heat Attenuation Factor (HAF): This is the amount of heat blocked by the fabric. Even though a fabric may be 100 per cent flame resistant, that does not mean it will block all of the heat to which it is exposed. An HAF of 85 percent means that it will block 85 percent of the heat the fabric encounters. This applies to a short burst of heat – typically less than one second. In the event of prolonged heat exposure, the HAF would be much lower.

Calories per Centimeter Squared: This is a number identifying the amount of energy that can be delivered to a point at a particular distance from an explosion. Once this value is known, the ATPV rating of the required for work at that distance from the potential flash hazard is also known.

Energy Break-Open Threshold (EBT): Primarily, this addresses the physical strength of the fabric with respect to thermal energy and at what value the fabric will fail.

Personal Protective Equipment: This term is primarily used to describe all PPE used by personnel to protect personnel. This includes fall protection, confined space, electrical hazards, minimum arc rating, etc.

Hazard Risk Category (HRC): This is a rating of exposure levels for particular types of equipment. The values range from zero to four, with a zero HRC with a zero HRC not requiring any ATPV-rated. The minimum ATPV rating for Arc Flash PPE Category One through Four are as follows:

Category One: five calories per square centimeter
Category Two: eight calories per square centimeter
Category Three: 25 calories per square centimeter
Category Four: 40 calories per square centimeter

EF PARTNER MEDIA

Product Showcases