Arc flash is one of the hazards faced by people who work with power lines, electrical panels, installations, and other equipment. Let’s deal with the causes of its occurrence, danger, and ways to avoid it. An arc flash is an electrical explosion that can occur while an electrical current is jumping from one conductor to another or to the ground. An arc flash PPE is a protective gear for the workers during this time.
The arc flash can produce a blast of heat and light that can cause serious injury or even death to anyone nearby.
Arc flashes can be caused by a variety of factors, including equipment failure, incorrect installation, human error, and environmental conditions. They can occur in any industry that uses electricity, including power generation and distribution, manufacturing, construction, and transportation.
Arc flash PPE (Personal Protective Equipment) refers to the protective clothing, equipment, and gear worn by workers who may be exposed to arc flashes. Arc flashes occur when electrical energy is released from an electrical arc, which can cause an explosion, intense heat, and flying debris.
What Is The Scientific Definition Of Arc Flash?
Arc flash is a leakage of electricity from conductors of electric current to objects that are not conductors in normal mode (e.g., tool, the metal case of equipment). Also, an arc flash can occur in case of an accidental connection of the phase and neutral conductor or conductors of different phases to each other.
Arc flash looks like a flash with sparks and light. At the same time, a large amount of heat is released, which can melt metal parts, and they can fly around.
The arc flash lasts a fraction of a second and stops in two cases. The first is when protection is triggered. The second is when the conductor is destroyed, and because of this, the conductivity of the area where the arc occurred (airspace) becomes too low for the further flow of electric current.
What Can Cause Arc Flash?
To protect the body from this type of accident, you must use the arc flash PPE.
Typically, arc flash occurs for the following reasons:
- Wear and tear on equipment;
- Ingress of dust;
- Damaged insulation;
- Entry of animals (for example, snakes or rodents);
- Tools falling on conductors;
- The human factor, etc.
After an accident, circuit breakers, contactors, and other equipment may fail and require expensive repairs.
The Impact Of An Arc Flash On A Person
Arc flash injuries are inevitable if a person is in the area of its effect and is not protected in any way. As a rule, there are arc flash burns, injuries from flying debris and metal, acoustic injuries, and eye damage. Fatalities are possible.
According to the level of danger, NFPA 70 E defines the boundaries of approach to electrical equipment:
- Flash Protection: includes a risk of second-degree burns due to high temperatures.
- Limited: there is a risk of a shock hazard.
- Restricted: there is a risk of shock. This arc flash ppe can protect your body.
- Prohibited (inner boundary): equates to making contact with the live part.
To determine the safe distance, the voltage class of the equipment should be taken into account. Thus, household appliances belong to low-voltage electrical installations, so their exposed conductive parts can cause injury if touched. But exposed conductive parts of installations above 2kV can strike at a distance of 39 mm.
How To Prevent Industrial Injury?
First, the enterprise must be equipped with means of arc protection. It reduces the time of disconnection of the arc to a minimum. This reduces the risk of personal injury, fire, etc.
In addition, regular diagnostics should be performed to identify outdated equipment. It should be upgraded or replaced. Also, technicians must detect insulation violations.
For their part, employees must follow safety techniques such as wearing arc-flash clothes and arc-flash PPE.
There are 4 arc flash categories of PPE that differ by the arc rating (measured in cal/cm²).
The basic set of clothes usually includes these items (all arc-rated):
- Long-sleeve shirt, pants, or full body coverall;
- Face shield or suit hood;
- Hard hat;
- Jacket, parka, rainwear, high-visibility appareling
- Ear protectors;
- Safety glasses;
- Heavy duty leather made gloves;
- Full-covered leather footwear.
The minimum arc rating for Category 1 is 4 cal/cm², Category 2 — 8 cal/cm², Category 3 — 25 cal/cm², and Category 4 — 40 cal/cm².
Wrapping It Up
Arc flash study specialists help figure out how to protect equipment and keep the staff safe by wearing arc flash PPE. They conduct arc flash training, where they explain the peculiarities of working with different types of equipment and provide detailed instructions. Usually, such training increases the level of safety at work and reduces the risk of injuries.