Let this destroyed face shield be your reminder to always wear your PPE.
Your face will thank you.

In the age of facial recognition (and in any age), it is good to protect your face so it remains recognizable. Driver’s license photos are bad enough without making it worse.

An arc flash can change your looks quickly. In the event an arc flash occurs, it is better to destroy the arc-rated face shield than your face. The “slightly used” face shield in the photo (yes, that’s me) is a not-so-subtle reminder of the kind of damage an arc flash can wreak.

NFPA 70E requirements

Requirements for face and head protection are found in various locations in NFPA 70E Standard for Electrical Safety in the Workplace. For selecting arc-rated protection, including the face shield or arc-rated hood, Section 130.5(F), Arc Flash PPE, lists two methods that include either performing an incident energy analysis or using the PPE category method.

When an incident energy analysis is performed, equations from IEEE 1584 are used to calculate the prospective incident energy in calories per square centimeter (cal/cm²) at a specific working distance. The arc flash boundary is also calculated. That’s the distance from a prospective arc flash source where the incident energy is 1.2 cal/cm².

The face protection must have an arc rating suitable for the arc flash exposure according to NFPA 70E 130.7(10)(c), Face Protection. How do you verify the arc rating is “suitable”? The calculated incident energy at the equipment location is compared to the arc rating of the protection—in this case, the face shield. Table 130.5(G), Selection of Arc-Rated Clothing, lists arc-rated face shields and arc-rated balaclavas or arc flash suit hoods for incident energy exposures equal to 1.2 cal/cm² up to and including 12 cal/cm². Above 12 cal/cm², only an arc-rated arc flash suit hood can be used.

If the PPE category method is selected, tables 130.7(C)(15(a) and (b) are used to determine an arc flash PPE category based on the equipment and specific parameters of maximum fault current, clearing time and minimum working distance. PPE categories range from one to four, with four being the most severe. Table 130.7(C)(15)(c), Personal Protective Equipment, is then used for selecting PPE based on the category. For arc flash PPE categories 1 and 2, an arc-rated face shield is required, although a full arc flash hood is also permitted. If a face shield is used, an arc-rated balaclava is also required for Category 2 or when the back of the head is inside the arc flash boundary as stated in Note b of Table 130.5(G).

In the blink of an eye

I have seen this story play out too many times. An electrical worker at a job site is wearing arc-rated PPE. Once the job is completed, they pack it up and store it in the truck. Getting ready to drive away, they suddenly remember one last task and head back inside to take care of it. 

Boom! An arc flash occurs. Their gear is sitting in the truck—this was only going to take a moment. With a burned face (and maybe more), they now get to spend time in the emergency room and begin a slow recovery—if they are one of the lucky ones.

It can happen to me

In the earlier years of arc flash, I was conducting testing in a high-power lab and recording a lot of video.

Once a test was set up and ready, I would have the lab technician count backwards from three, like we are about to launch. From the safety of the control room, when he reached one, I turned my head away and put my hands over my ears. It was very loud and the ultraviolet (UV) light was blinding—literally, as I found out the hard way.

During one test, I was focusing the camera to capture the arc flash, except this time, the lab tech forgot to count backwards. Boom! Without warning, I was looking right at the arc flash when it happened. In stunned silence, I could not see. I always imagined it would be completely black, but instead it was a very bright purple. I could only see on the periphery, so fumbling my way back to the chair I sat down to find out if this would go away. Although it took some time, my eyesight eventually returned with no lasting damage. Quite a personal example of the importance of UV filtering for face protection.

NFPA 70E states the first priority in the hierarchy of risk controls is to eliminate the hazard. Although live working should be a last resort, if an arc flash does occur, it is better to destroy the face shield than harm your face.

Jim Phillips