- When Is Arc Flash Personal Protective Equipment Required?
- NFPA Arc Flash Boundary
- Limited Approach Boundary
- Restricted Approach Boundary
- Prohibited Approach Boundary
- Arc Flash PPE Categories
- Choosing the Right PPE
- Training for Arc Flash Protection
- Storing Arc Flash PPE
Imagine working near exposed energized electrical conductors or circuit parts and suddenly before you have time to try and catch the tool you dropped, you’re faced with a blinding flash, an incredible wave of heat, a deafening noise, and are thrown across the room.
Arc flashes have been known to reach temperatures of up to 35,000° F. That’s four times hotter than the sun! That deafening noise was 140dB and can result in permanent hearing loss. That bright flash was probably recorded at 1 million lux, enough to do permanent eye damage. Every year, there can be as many as 30,000 arc flash incidents that result in 7,000 burn injuries, 2,000 hospitalizations due to serious injury, and 400 deaths.
Arc flashes happen so fast that employees have zero time to react. For that reason, it’s important to implement a safety program that focuses on minimizing the risk of arc flash events and reducing the risk of injuries. One of the most effective options employers can do to protect employees from these dangerous situations is to ensure that all employees working near arc flash hazards wear the appropriate arc rated personal protective equipment. This means using flame retardant clothing, using rubber insulated tools, and having a number of other different types of specialty equipment on hand.
When Is Arc Flash Personal Protective Equipment Required?
NFPA 70E specifically states, “Employees shall wear arc rated clothing wherever there is a possible exposure to an electrical arc flash above the threshold incident energy for a second-degree burn (1.2 cal/cm2).” This often requires an arc flash risk assessment for calculating the potential incident energy of a piece of electrical equipment. Once that has been determined, then the employer can proceed with picking out the arc flash clothing that either meets the threshold limit or exceeds it.
Now, the most effective way to keep people safe from arc flashes is to make sure they don’t enter an area without taking the right precautions. The NFPA has laid out specific arc flash boundaries in their 70E standard for this exact reason. It uses distance and the energy potential of the arc flash hazard to determine the category of arc rated clothing required.
Following the National Fire Protection Association 70E standard is not optional. It must be referenced to determine what type of PPE to wear and when to wear it while working around electrical equipment.
NFPA Arc Flash Boundary
The arc flash boundary is the distance at which an arc flash is dangerous should one occur. Specifically, this boundary is defined as the distance where a person in the area may be exposed to 1.2 cal/cm2 of energy for 0.1 seconds. This energy threshold and duration of time are enough to result in second degree burns if any skin is exposed at the time of the incident.
Incident energy is calculated by looking at the voltage and the total fault exposure levels. If an arc flash occurred while a worker was within a specific arc flash boundary, it’s possible for the electricity to pass through that person, resulting in extreme burns and even death depending on how much incident energy they were exposed to. Anyone who needs to go within an arc flash boundary needs to wear the level of personal protective equipment required based on the voltage of the machine being worked on.
Limited Approach Boundary
The limited approach boundary should only be crossed by those who are trained and qualified, and only in situations where someone needs to perform a specific task within that area. People should never walk through this area just for convenience, even if they are trained on working with electrical equipment.
Ideally there should be either a physical boundary or at least a visual boundary such as floor marking tape or a safety sign. The 70E standard specifically states that any barricades cannot be put any closer than this limited approach boundary.
Restricted Approach Boundary
Entering a restricted approach boundary area is even more dangerous because it’s closer to the source of danger. Any individuals tasked with working within this boundary will need a higher level of PPE and use insulated tools in order to stay fully protected against arc flash hazards. They will also need specialized training for shock prevention to make sure they don’t cause an arc flash event themselves.
Lastly, before entering a restricted approach boundary area, the individual must get written approval for their task. This plan must cover the appropriate requirements to make sure the employee keeps all body parts out of the prohibited approach boundary.
Prohibited Approach Boundary
The prohibited approach boundary, or inner boundary, refers to any area that must be treated as if the person was coming into direct contact with the electrified part of the machine. As with the other boundaries, only those who have had the proper training should enter, and approval of the plan must be received before anyone even approach these areas.
Arc Flash PPE Categories
Personal protective equipment for arc flash safety is broken up into a total of four categories. Level 1 contains the least PPE, while level 4 contains the most. These categories match up to the level of risk involved in a given situation. For example, if someone is working with low-voltage wiring that is not likely to create an arc flash, they will not need extensive PPE. If someone is working on a high-voltage machine where there is a serious risk of an arc flash, category four arc flash rated clothing is likely going to be needed.
PPE Category 1
The first category of arc rated, and fire-resistant PPE is necessary for energy levels up 4 cal/cm2. All the following items of PPE must have a minimum arc rating of 4 cal/cm2 to protect employees with this arc flash hazard level.
- Arc-rated long-sleeved shirt and pants or a coverall
- A hard hat with arc-rated face shield
- Hearing protection
- Safety goggles or glasses
- Leather gloves or rubber insulating gloves and leather protectors
- Leather footwear
PPE Category 2
The minimum arc rating for category 2 arc flash PPE is 8 cal/cm2. Category 2 is quite similar to category 1, but with two more additions:
- An arc-rated balaclava
- An arc-rated jacket
PPE Category 3
Category 3 requires a significant jump up in protection. It's for any areas where the energy level is up to 25 cal/cm2. Category 3 requires multiple layers of fire-resistant clothing including cotton undergarments. In addition to the items listed in category 2, employees should wear:
- An arc flash suit jacket
- Arc flash suit pants
- An arc flash suit hood
PPE Category 4
This is the highest level of arc flash personal protective equipment. It’s used for any situation that has energy levels above 25 cal/cm2. These are some of the most dangerous areas where an arc flash could easily kill people in a fraction of a second. At category 4, the employees will need to wear all the same type of PPE as in category 3, except it should be rated at 40 cal/cm2.
Choosing the Right PPE
Determining when arc flash PPE is required and which category of PPE is necessary is not always as straightforward as many would like. There are guidelines available from NFPA as part of the 70E standards that help employers and employees determine exactly what is required.
However, when employees need to act quickly to respond to or prevent an emergency situation it can be difficult to quickly make a decision. A good rule of thumb for this type of urgent response is to use the highest category of personal protective equipment that could be required. With that being said, it’s much better to wear a category 4 set of PPE when only a category 2 would be needed.
Training for Arc Flash Protection
There is quite a bit of training that goes into being able to perform dangerous work such as this. In addition to becoming proficient at the actual work that needs to be done, employers should also provide employees with training on the proper use of arc flash personal protective equipment.
PPE cannot keep employees safe if they are not wearing it properly. Remember, an arc flash can create a blast that can throw an employee across the room and cause them to lose consciousness. Wearing PPE properly can mean the difference between minor injuries and a fatal accident.
Employers must offer electrical safety training and regular review sessions to all employees who work with electrical equipment. Providing a supportive environment around arc flash hazards will help cement the company’s safety culture for the better. Employees will become more engaged and motivated to do their jobs well and do them in a way that protects themselves and their co-workers.
Storing Arc Flash PPE
While some jobs require people to wear arc flash personal protective equipment on a regular basis, that is often not the case. In many facilities, this type of PPE will only be needed a couple times per year, or even less. When this is the case, it is important to ensure the equipment is stored in a way that is safe, yet accessible.
One of the first things to keep in mind when storing arc flash PPE is accessibility. In the event of an emergency, designated employees should be able to find and put on the PPE very quickly. Placing the PPE in a storage closet that is marked with a label on the outside can be a very effective option.
In addition to accessibility, it is important to keep this type of equipment safe. If the equipment gets a hole or tear in it, the safety of the person wearing it will be compromised. With this in mind, employers are responsible for inspecting the PPE on a regular basis to ensure there are no problems. If a hole or other issue is found, it needs to either be properly patched or replaced.
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