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The Dangers of Arc Flash in a Data Center and How to Avoid It

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shock hazardA well-planned and well-managed data center anticipates potential hazards and works to minimize their risk. Additionally, by anticipating potential hazards, a data center can have appropriate response plans in case a potential hazard becomes reality.  At times, the level of preparation and planning can feel like overkill.  After all, what are the odds that the majority of these hazards or disasters will actually happen?  Probably very slim.  But, what happens if they happen to your data center.  It is far better to plan ahead then try to play catch up because playing catch up when disaster strikes usually means a disaster will be more expensive, damage more property, and possibly injure more people.  Arc flash is one potential hazard a data center may face.  But, it is not an unlikely, far-fetched hazard, it is very real.  Arc flash injuries are one of the most common on-the-job electrical injuries and can be incredibly harmful and even fatal.

A data center cannot simply turn off electricity to mission-critical servers if they need to be accessed or serviced.  Doing so would lead to downtime, frustrated clients, and lost revenue.  To understand why arc flash is concerning, it is important to have a clear picture of what arc flash is and how it can happen in a data center.  Consulting-Specifying Engineer elaborates on what arc-flash is and why it is such a significant hazard, “An arc flash is the result of an electric current passing through air as the result of conductor failure, equipment failure, or the accidental connection between voltage sources such as dropping a tool across buses in distribution equipment. The flash is immediate but the resultant release of energy can cause severe injury, and possibly death. There is a potential for a tremendous amount of heat to be released, which can result in overpressures, as well as flying debris. The energy released can cause temperatures exceeding 35,000 F, which can vaporize steel, copper, and aluminum. Inhaling these vaporized metals could be fatal. Injuries or fatalities could occur if personnel are in the area in front of an arc flash, which could send projectiles such as parts of metal buses away from the blast. Also, molten metal can cause significant burns, and the sudden air pressure increase can knock personnel off their feet. Each year, more than 2,000 people are treated in burn centers for injuries from arc flash incidents.”

What is truly frightening about an arc flash (as if it was not frightening enough already), is that an arc flash can set off a chain of harmful and dangerous events.  When an arc flash occurs in a data center, there is a significant amount of electricity around.  As the arc flash is happening, it can melt and even vaporize conductive material and with enough energy, can lead to an arc blast.  An arc blast is the result of the expansion of metal as it vaporizes.  An arc blast can cause additional injury and equipment damage as well as downtime.

Arc Flash Protective Gloves
Arc Flash Protective Gloves – Image via: OSHA

There are many things that can lead to arc flash.  Often, arc flash is the result of human error.  Additionally, if certain items such as tools or other items are stored on top of components, it can lead to an arc flash.  And, lack of preventative maintenance is a common reason arc flash occurs.  Preventative maintenance and visual inspections are one of the easiest things any data center personnel can do to prevent a myriad of problems, arc flash included.  Another reason arc flash can occur is if equipment was not installed properly.

As you can see, arc flash is highly preventable with proper planning, installation of equipment, and consistent maintenance.  It is important to take every precaution to prevent arc flash.  Not only because you can prevent the risk of equipment damage and downtime, but because there are certain safety standards put in place by OSHA (Occupational Safety and Health Administration) for individuals who work with electrical equipment.  If you do not take proper precautions, you could by liable for on-the-job injuries that could have been prevented.  To remain OSHA compliant, you must have a proper safety program with defined responsibilities in place.  Your personnel must wear personal protective equipment (PPE).   Additionally, personnel must be trained on the hazards of arc flash and how to use appropriate tools to create a safe working environment.  All equipment should be properly labeled with warnings.  And, it is important that you calculate the degree of arc flash hazard.

Image via: OSHA

Many data centers think that if they simply install equipment the correct way and complete preventative maintenance, that they are doing enough to prevent arc flash.  It is important that a data center does not skip the arc flash analysis.  Calculating your degree of arc flash hazard is essentially a risk assessment that will provide you with the information you need to know whether or not you are doing enough or need to improve to prevent arc flash.  TechTarget explains why arc flash hazard assessments are best left to special expert contractors, “But there is no substitute for a formal arc-flash analysis. It’s not a simple job, but if it’s done right — especially for a new electrical design — it might identify ways to mitigate arc-flash hazards and identify work that could be done without either a shutdown or a hazard suit…A thorough arc-flash analysis requires a comprehensive short-circuit study first. While this is a standard requirement of the electrical design process, an arc-flash analysis must evaluate the electrical design from a different perspective to mitigate arc-flash hazards. A breaker coordination study must also be done with the same goal in mind, even though it may have been done before. Breaker coordination ensures that the breaker nearest the fault condition trips first. If done with arc flash in mind, a breaker coordination study could help you select different circuit breakers or fuses than might normally have been chosen.”

Once the degree of arc flash hazard has been assessed, a data center can begin to implement arc flash risk mitigation measures.


Arc Flash Risk Mitigation Measures:


–   Complete assessment of data center facility and all of its electrical equipment. By completing a comprehensive assessment of data center equipment and, in particular, the electrical system, you can begin to identify potential hazards or problems within your system.


–   Documentation of assessment in one place, where all past and future assessments can be maintained for reference. Make any notes about the condition of the equipment, as well as when it was last maintained so that proper maintenance is never neglected.


–   Implementation of protective devices to prevent arc flash. After assessments have been made, if protective devices, such as arc-resistant switchgear or other equipment, can be installed to prevent arc-flash.  Electrical Contractor explains how arc-resistant switchgear works, “Arc-resistant switchgear is designed to redirect arc energy up and out of the equipment through ducts/vents outdoors away from equipment operators. The system is designed with vent flaps that will open under the pressure of an arcing fault and redirect the super heated gases and arc flash energy up and out of the equipment, away from personnel.”


–   All equipment must be properly labeled with any necessary diagrams or safety warnings provided in plain sight.


–   Only qualified, trained personnel should work on electrical conductors or other electrical equipment.


–   Implementation of defined protection boundaries according to NFPA 70E guidelines.


–   Use of protective safety equipment because it minimizes arc flash exposure should an incident occur.


–   Grounding is another option to reduce the risk of arc flash, as Schneider Electric outlines, “The method of system grounding can have an impact on arc-flash hazards.  High-resistance grounded (HRG) systems are not new, but recently they have been promoted as an arc-flash mitigation means.  The idea is that HRG systems inherently limit the energy delivered to a ground fault by limiting the available fault current to just a few amperes, providing a great deal of protection.”


Implementing proper arc flash risk mitigation measures is an important thing for any data center to do.  Not only does it significantly reduce the risk of damage to equipment and the likelihood of downtime occurring but it also dramatically reduces the risk of injury to personnel.  OSHA has strict guidelines in place for a reason – to protect worker safety through reasonable safety expectations.  If you do not comply with NFPA 70E guidelines for arc flash protection, you can be cited by OSHA.  Protect your facility, your equipment, your customers, and your personnel from the hazards of arc-flash by calculating your risk of an arc-flash occurring and by implementing proper risk mitigation measures.






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