You already knew that arc flash releases hot gas and radiant energy up to 4 times the temperature of the sun, right? Let's ponder that for a minute. When arc flash happens, the ambient temperatures can reach 35,000° Fahrenheit. And the arc blast, or pressure wave, is just as intense. Think about that the next time you burn your mouth on a slice of hot, bubbly pizza and see your life flash before your eyes. Poor thing. You know something? Arc flash is much, much worse.
Knowing the dangers of arc flash is the only way you can be sure you aren't putting yourself into the line of fire. See, it's not enough to kinda know about this stuff. Being aware of how to avoid injury or death is the difference between making happy hour on Friday and lying in an emergency room.
Did you know an arc flash can happen in many different ways?
- Spikes in voltage
- Touching test probe to wrong surface
- Worn connections
- Gaps in insulation
- Improperly installed parts
- Dust or corrosion
- Unsafe work procedures
- Mishandling tools and wires
- Negligent preventative maintenance
- Not checking for loose termination
- Not testing stored energy
- Improper electrical equipment or system design
- Improper modification
Here’s a breakdown of the types of eye protection you can choose from:
Glasses: Safety glasses should have frames made from metal or plastic and lenses must be impact-resistant. They’ll protect your eyes from things that could bruise, pierce or damage your eyes. Keep in mind there are gaps around the glasses that debris can enter, but sealed or foam-backed eyewear is available.
Goggles: Wear these when you need tight-fitting protection that will completely cover your eyes, eye sockets and the area surrounding the eye. Typically, goggles are necessary when working with dust, splashes, vapors, splashes or need when you need protection from impact.
Faceshields: These usually extend from eyebrows to below the chin and across the worker’s entire face and may be polarized for glare protection. These protect against nuisance dust and chemical splash. Faceshields must be used in conjunction with safety glasses or goggles, never on their own.
Side shields: These offer added protection on safety glasses when there is a hazard from flying objects that could go under or around the eyewear.
Eye protection should be impact resistant, UV resistant and provide coverage over the entire eye. Workers should wear eyewear like goggles or safety glasses that offer protection from dust, impact, UV and infrared radiation and irritation from fumes. The best type of protection in these cases would be foam-backed eye protection, because they provide coverage and protection to the entire eye area.
When selecting PPE to Protect Eyes & Face against an Arc Flash, what is the most important selection criteria?
Of course the arc protection level is the most important criteria, i.e. the arc rating (ATPV) as per ASTM F2178 or the arc protection class as per GS-ET-29. However, typically the higher the protection level, the lower the luminous transmittance also called Visible Light Transmission (VLT). Considering the usually poor illumination inside switching cabinets and several other typical electrician workplaces also this VLT is a deciding safety factor. Due to bad visual conditions mistakes may happen – finally even causing an arc flash accident. Note that products with a VLT between 50% and 75% (VLT Class 1) already may need additional illumination. Products with a VLT of less than 50% are supposed to be "very dark". Those products only should be used, when extreme high protection is required and provided by a particular product. For the same reason the field of view, i.e. the peripheral area one can see without moving the head, is important, e.g. when a switching hood is required.