What’s an arc flash?
An arc flash is an electrical explosion that can happen along with energized equipment such as an air conditioner, conveyor, or even a lightbulb.
When electrons move on a conductor back and forth – like on a wire – a small area outside of that conductor is energized. Voltage can push those electrons of the conductive surface and on the atoms in the air. By their electric charge, these atoms become ions.
The air around us is good insulation to prevent those ions from triggering an explosion, but still, arc flash can occur. If another conductor enters this energized area, a wrench, moisture in the air, dust build-up or a worker’s hand, the electrons will travel to that new path.
As the electrons are moving between conductors, an arc occurs. We see this every day on a smaller scale when switching on a lightbulb. However, on a larger scale, the arc between two conductors generates very intense heat.
Electric arcs can reach nearly 20,000 degrees Celsius, a temperature four times hotter than the sun!
According to the voltage of the machine, workers located at more than 7 meters, equivalent to the length of two cars, are still at risk of suffering second-degree burns.
Superior Glove has produced a video that illustrates what is an arc flash, with an interesting perspective regarding hand protection.
HOW TO PROTECT YOURSELF AGAINST ARC FLASH?
The only foolproof way to eliminate the risk of an arc flash is to de-energize the equipment through lockout and tag out procedures.
Here are some steps to implement in order to ensure the safety of the work teams when working on energized equipment:
- Provide a safety program with defined responsibilities.
- Calculate the arc flash risk level.
- Use appropriate personal protective equipment (PPE) for all workers.
- Train workers on arc flash hazards.
- Use the appropriate tools to work safely.
- Implement equipment lockout/tag out procedures.
Also, if your teams must work with energized equipment, the Canadian standard CSA Z462 used since January 2009, as well as the American standard NFPA 2112, will help you define the approach limits designed to protect employees.
APPROACH LIMITS
Safe distance
It’s the farthest distance from the energy source. If an arc flash is produced, this limit is the distance where the employee won’t be affected.
Limited approach
This is the minimal distance where unqualified personnel can safely access. No unskilled person can get past this boundary toward the energized equipment. Qualified people must use the appropriate personal protective equipment and be trained to perform the required work before crossing this limit.
Restricted approach
This boundary can only be crossed by qualified personnel wearing the appropriate personal protective equipment. The qualified workers must also possess an approved plan signed off for the work to be carried out.
Prohibited approach
Only qualified personnel wearing the appropriate PPE can cross the threshold of the prohibited approach boundary. Workers also need specific training to work on energized equipment, a detailed plan justifying the necessity of performing this work as well as a risk assessment to cross that limit.
SELECTING WORK EQUIPMENT: PROTECTING YOUR HANDS!
To intervene on energized equipment, workers require protection. The human body is vulnerable to an arc flash, and the following information found in this article concerning gloves is also applicable to any other personal protective equipment.
When selecting gloves designed for arc flash protection, we need to look at the glove’s ATPV (Arc Thermal Performance Value). The ATPV represents the incident energy rate with a 50% chance of causing second-degree burns. For example, with a glove having an ATPV value of 8.2 cal/cm² you have a fifty percent chance of suffering from a second-degree burn caused by an 8.2 cal/cm² arc flash. Therefore, the higher the ATPV rate, the more protective the glove.
Dexterity® Protective Gloves Against Arc Flash
Dexterity gloves feature a Kevlar®/Protex® yarn blend for impressive heat and cut resistance.
Scientifically engineered to be flame resistant, these gloves offer a Category 3 rating and an APTV rating of 25 cal/cm², as well as ANSI Level 5 cut protection to protect workers from electrical arcing and cut hazards.
The flexible and comfortable neoprene palm is flame resistant and offers an exceptional grip without hindering dexterity, making this glove perfect for mining and oil and gas industries where arc flash protection is essential.
These gloves are also compatible with touchscreens and are latex-free.
Characteristics
- Thermal protection rated up to 260°C (500°F)
- Arc tested to Level 3 with an arc thermal performance value of 25 cal/cm2
- High flame retardant properties and good oil resistance
- Non-slip flame resistant neoprene palm
- Compatible with touch screens
