An arc flash is a dangerous situation in which an electrical current leaves its intended path and leaps through the air from one conducting source to another, or even sometimes the ground. Many times the transfer of electrical energy resembles and arc, hence the term arc flash. However, it is important to never underestimate the power behind an arc flash. An arc flash can vaporize metals, plastics, and even flesh. Many times arc flashes cause irreversible damage and harm to people and surrounding objects. In fact, most people injured in arc flash situations often never return to the same quality of life due to severe injury stemming from heat and burns. The heat of an arc flash has been calculated to be near 35,000 degrees Fahrenheit which is four times as hot as the sun’s surface!
What Causes an Arc Flash?
There are many possible contributors towards an arc flash, which makes it difficult to really fully stop one from occurring. Some common culprits that may add towards the probability of an arc flash include dust, condensation, corrosion, material failure, faulty construction, dropping a tool, or simply accidental touching.
National Fire Protection Association (NFPA) Boundaries
In an attempt to help protect employees and visitors from electrically charged equipment possible of creating arch flashes, certain safety boundaries have been put into place by the NFPA. The boundary resembles a target and in the middle is the energized equipment, and then there are four outer rings around the center with each ring labeled and specified for safety. The first ring, closest to the center (energized equipment) is called the prohibited approach boundary, then the next ring further out is called the restricted approach boundary, the next ring is called the limited approach boundary, and the furthest ring out from the center is called the flash protection boundary. Let’s quickly describe each boundary.
- Prohibited Approach: Being within this boundary during an arc flash would cause the same damage as making contact with the actual live part.
- Restricted Approach: Being within this boundary possesses an increased risk for shock.
- Limited Approach: This boundary still possesses a shock hazard.
- Flash Protection Boundary: If within this boundary the possibility for heat related 2nd degree burns is likely. However, most injuries from this boundary are usually curable.
How to Stay Safe
The NFPA 70E provides many helpful guidelines to keep safe when working around areas that pose electrical hazards. One common method used to help provide protection from dangerous electrical currents is the use of Personal Protective Equipment or simply PPE. PPE consists of clothing materials and protective equipment that can be worn on top of regular clothing that can provide protection against extreme levels of heat or brightness associated with hazards such as arc flashes. Common PPE equipment includes eye and face protection, gloves for hand protection, coverall suits and fire resistant pants for body protection, and hoods for further face and neck protection.
Never Underestimate the Hazard of an Arc Flash
The danger of an arc flash is very real; many arc flash situations cause irreversible damage or are even fatal. All employees who work around potential arc flashes or electrical hazards should be provided personal protective equipment to help protect them from the possibility of electrical currents. Furthermore, staff should also be trained on the safety boundaries associated with electrical protection to create the safest environment possible for everyone.
- Arc Flash Boundaries
- NFPA 70E Update Overview
- Arc Flash: Common Beliefs Debunked
- Arc Flash PPE
- Arc Flash Accident Video
- What is Fault Current?