Personal Protective Equipment (PPE) is the last line of defense against injuries. When it comes to arc flash, PPE is typically needed to protect a worker from electric shock and burns.
NFPA 70E requires appropriate PPE to be worn when a worker is inside one of the protective boundaries around electrical equipment. Specifically, workers within the Restricted Approach Boundary need PPE that protects them from electric shock, and workers within the Arc Flash Boundary need PPE that protects them from arc flash burns. These two requirements are independent, so workers may need one kind of PPE or the other, or they may need both.
When an employee is working within the restricted approach boundary, the worker shall wear PPE in accordance with 130.4. When an employee is working within the arc flash boundary, he or she shall wear protective clothing and other PPE in accordance with 130.5. All parts of the body inside the arc flash boundary shall be protected.
Arc Flash PPE Elements
PPE for arc flash includes arc-rated (AR) clothing. AR clothing has been tested against exposure to an electric arc, and its AR rating (expressed as a number) represents the amount of incident energy that the clothing is able to block or absorb. Older PPE may be marked as flame-resistant (FR), which is not the same. All arc-rated equipment is also flame-resistant, but not all flame-resistant equipment is also arc-rated.
Elements of AR clothing include shirts and pants, coveralls, face shields, hoods, and balaclavas. More extreme hazards may require the use of full flash suits, worn as an outer layer over other protective clothing. Other PPE typically required when there is a risk of arc flash include safety goggles, hearing protection, hard hats, leather gloves, and leather footwear.
None of the clothing worn next to a worker's skin should include meltable materials, such as nylon or acetate. If these materials are exposed to the extreme heat of an arc flash, they can melt onto a worker's skin and stick there, causing extreme burns. Natural fibers (such as cotton) are the best choice for these underlayers.
The PPE recommendations included in NFPA 70E are mostly focused on protecting workers from electric shock and burns. The standard also considers the extremely loud burst of sound (in its requirement for hearing protection). However, additional protection may be needed to keep workers safe from other kinds of injury. Arc flashes can cause powerful blasts of pressure, scatter shrapnel, or knock workers down or into other equipment.
Determining Appropriate PPE Levels
Wearing too little PPE can expose a worker to lethal injuries. On the other hand, highly protective PPE can be bulky and uncomfortable. Over-protection can restrict a worker's vision and movement, increasing the chance of an accident as well as increasing work time and difficulty. It's easy for a worker to "forget" to wear equipment that is difficult to put on and take off, especially when it seems excessive.
NFPA 70E includes two methods that can be used to find the right amount of PPE for a given task on a given set of equipment:
- Incident Energy Analysis - the expected incident energy of an arc flash is calculated for each piece of equipment, according to its actual installation. The incident energy is then used to determine how much protection a worker would need.
- Arc Flash PPE Categories - each piece of equipment is found on a set of tables in the standard. The tables assign one of four categories to the equipment, with each category requiring a specific set of PPE and having a minimum arc rating for the clothing to be worn.
The PPE tables provided in NFPA 70E are valid only for a limited range equipment and installations. Where the equipment or installation does not match one of the tables' entries, the analysis method is needed. Whichever method is used to decide on the appropriate level of PPE, that information needs to be posted on the equipment with an informative arc flash label.