Since an Arc Flash accident occurred at your workplace recently during an open panel electrical inspection, the safety officer has been conducting safety trainings for the employees. You read a previous article titled “What Is An Arc Flash?” to educate yourself on Arc Flashes and the hazards associated with them when they occur. The safety officer recently formed a team to search for solutions that could minimize or reduce the risk of an Arc Flash from occurring again during an inspection. You joined the team and are ready to work on the project.
As a review, an Arc Flash is an energy discharge of light and heat that forms when a fault occurs in an electrical circuit. The arcing results in a tremendous amount of energy being released as current flowing through ionized air. Hazards associated with an Arc Flash are flying molten shrapnel, extreme temperatures, sudden air expansion causing blast pressure waves and hearing loss; all leading to severe injuries or even death
During a team meeting, the safety officer presented the National Fire Protection Association (NFPA) publication titled 2018 Edition NFPA 70E which puts forth new and revised regulations to protect workers from hazards that can cause injury or death. See a past article on these new regulations that describe a “Hierarchy of Controls” for establishing safe working procedures. The team reviewed the Hierarchy of Controls which is implemented in a sequential progression starting with the following:
1. Elimination of the Risk
3. Engineering Controls
5. Administrative Controls
6. Personal Protective Equipment
Most electrical equipment must be inspected under “full load” to obtain accurate infrared and ultrasound data; therefore, de-energizing the equipment and elimination of the hazard is not possible for these inspections. The safety officer moved to the next level in the hierarchy – substitution. Can the hazard be replaced with something that does not produce a hazard but still enable inspections to be performed on fully loaded electrical assets? You immediately remember reading an article explaining the utility of Electrical Maintenance Safety Devices.
You being to share knowledge about EMSDs, what types of EMSDs are available and, why companies are adopting these devices:
* Electrical Maintenance Safety Devices [EMSDs]
EMSDs maintain an energized compartment’s closed and guarded condition during an inspection process thereby reducing the hazards for the inspector. Some EMSDs add efficiency and safety to the inspection process while others provide continuous monitoring to detect problems earlier. Examples of EMSDs are Infrared Inspection Windows, Ultrasonic Inspection Ports and Detectors, Online Monitoring Systems and Intelligent Asset Tags.
* Why are Companies Adopting EMSDs?
Electrical systems have become more complex and as such, companies recognize the need for more frequent inspections to find faults before the system fails completely causing a costly downtime. EMSDs also minimize the hazards associated with electrical inspections such that these inspections can be performed more frequently and efficiently.
After you explain what EMSDs are and why companies are adopting them, your team determines the next step would be to perform a Criticality Assessment of every asset to determine what types of EMSDs would be required for inspections. The team has more work to do to ensure that the risk of another Arc Flash at the workplace is mitigated.
Unfortunately, there was an accident at your workplace a few days ago and several team members were injured. You heard the safety office declare that the accident was an Arc Flash. After viewing the remnants of this accident, you wanted to learn more about an Arc Flash. Let’s research the anatomy of an Arc Flash.
An Arc Flash is an energy discharge of light and heat that forms when a fault occurs in an electrical circuit. The arcing results in a tremendous amount of energy being released as current flowing through ionized air. An Arc Blast, separate from an Arc Flash, is a supersonic shockwave produced when the uncontrolled arc vaporizes the metal conductors. The terms are used interchangeably however, they really are different entities.
As an arc develops and gets hotter, the electrical resistance decreases and draws more and more current until some part of the system melts, trips or evaporates. When an uncontrolled arc develops and forms at high voltages, the Arc Flash can produce deafening noise, super heated shrapnel, supersonic concussive forces, intense high energy radiation and temperatures that far exceed the temperature of the Sun.
An Arc Flash also produces a cloud of plasma and ionized particles and if inhaled, the ionized gas causes severe burns to the airways and lungs. The charged particles may also be attracted to metallic objects nearby such as jewelry, belt buckles, keys and eyeglass frames resulting in severe burns.
Hazards of an Arc Flash/Blast
1. Shrapnel – Arc Flash/Blasts spray droplets of molten metal at speeds that exceed 700 MPH that can easily penetrate standard Personal Protective Equipment (PPE).
2. Extreme Temperatures – Arcs produce some of the highest temperatures recorded on earth; up to 35,000° F which is three times the temperature of the Sun.
3. Sudden Air Expansion – All known materials are vaporized at this temperature. The rate of expansion is comparable to a pea sized piece of copper expanding to the size of a boxcar. Blast pressure waves have thrown workers across the room.
4. Fatal Burns – Fatal burns can occur even when the worker is several feet away from the arc. Clothing can ignite from 10 feet away unless proper PPE is used.
5. Hearing Loss – An Arc Blast can have a sound magnitude of 140 dB two feet from the arc and can cause permanent hearing loss.
The National Fire Protection Association (NFPA) published the 2018 Edition NFPA 70E putting forth new and revised regulations to protect workers from hazards that can cause injury or death. See a past article on these new regulations that describe a “Hierarchy of Controls” for establishing safe working procedures.
An Arc Flash or Arc Blast is an extremely dangerous event that can cause injury or death to workers and damage to electrical assets and structures. Understanding the anatomy of an Arc Flash or Arc Blast can raise the awareness of workers in hazardous environments. Recognizing the hazards associated with an Arc Flash or Arc Blast helps workers understand why the use of PPE is critical when working with energized electrical equipment. Regulations, like the 2018 Edition NFPA 70 E, are created to protect workers
If I had a dollar for every time I got asked to provide a blanket statement or certificate that IR windows are Arc Resistant or Arc Tested, I would have been able to retire already. Seriously.
Unfortunately, I end up having to make a long explanation about how this is impossible to do. Why? Simply put, there is no standard test protocol that has been developed, neither in North America (UL, IEEE, CSA or ANSI) nor Europe (IEC), that would provide a means of performing a standardized test on just an IR window. Rather, the standards that exist are for testing complete switchgear assemblies for Arc Resistance. These tests are destructive in nature – an intentional bolted fault condition is created at a predetermined test voltage, available fault current magnitude and time duration. The IR Window is not in the current path of the fault; but, it will see the extreme pressures and temperatures created when the fault is initiated. The switchgear is what passes or fails the test. If that switchgear happens to have IR windows fitted in it and still passes the test, it gives that switchgear OEM the ability to sell the equipment with those particular IR windows fitted as an option to their client base. It does NOT mean that those IR windows are not Arc Resistant certified or Arc Tested for all applications with all OEMs.
The best analogy is the automotive vehicle crash test. Acme Air Bags is selected by Generous Motors to supply the front air bags. Generous Motors successfully crash tests their vehicle and it is certified by the National Highway Traffic Safety Administration – the body that created the test standard and overseas the testing. Despite this successful test, Acme cannot make blanket statements that his product meets NHTSA standards and will work in any and every car make/model. Similarly, IR Window manufacturers cannot make blanket statements about IR window Arc Ratings just because they did not cause one switchgear OEM’s destructive test to fail.
So, why do customers continue to ask for this type of blanket statement or certificate? Frankly, it is because of the marketing statements made by some in the industry that lead them to believe that such documentation exists. This includes statements like:
* “Arc Flash Testing, IEC 62271-200 (KEMA) to 5kV, 63kA for 30 cycles at 60 Hz”
* “Torture TestedTM to the highest arc blast test ratings”
* “IEEE C37.20.7: 63kA for 30 cycles at 60 Hz Arc tested at KEMA”
* “Maintains panel arc test ratings up to 63 kA when properly installed.”
* “Arc flash tested against a 50KA short circuit for 1 second at 11KV”
I can’t decide which of these statements makes me cringe the most. I am flabbergasted that someone was able to trademark the phrase “Torture Tested” as this is the absolute worst kind of marketing-
speak. But the statement that the product, “Maintains panel arc test ratings up to 63 kA when properly installed,” is probably the most egregious overreach as it clearly indicates you can use this product anywhere without any risk of invalidating your switchgear arc resistant ratings. The other statements are less blatantly misleading but should be at least marked with an asterisk and a note that explains that these tests are related to switchgear tests and standards, not window tests and standards which don’t even really exist.
One further item of note – neither IEEE nor IEC issue any kind of certificates of compliance. The International Electrotechnical Commission (IEC) is a standards organization that writes and updates standards for all electrical, electronic and related technologies. Electrical equipment outside of North America is usually designed to meet IEC standards. Independent testing labs are the entities that actually perform the tests and can issue reports and certificates of IEC standard’s compliance. IEC 61439 is the standard for Low voltage switchgear (<1KV) while IEC 62271 includes sub documents relating to Medium and High voltage switchgear (>1KV up to 52KV). IEC 62271-200 specifically has test standards for Arc Testing of switchgear and is often cited by IR window manufacturers. IRISS has had switchgear tested to IEC 62271-200 successfully with several of our IR window products installed.
IEEE is the Institute of Electrical and Electronic Engineers and has a Standards Association (IEEE-SA) that develops global standards for industries and technology. One of the committees within IEEE-SA is the IEEE Switchgear Committee that develops and updates the C37 series of standards for Low and High voltage equipment. IEEE C37.20.2 has requirements for static load and impact testing of viewing panes which includes IR windows (these are actually window tests) while IEEE C37.20.7 has test requirements for arc resistance testing of switchgear which may have windows fitted.
So, as a buyer of IR windows, what should you do? You just did it – educate yourself about what these standards mean and, more importantly, what they don’t mean.