Session 4 Lewis McCormick Paper FINAL

Session Four: Using Infrared Windows to Reduce the Risk of Arc Flash During Live Thermographic Inspections

2013 Arc Flash Conference IDC Technologies 1

Session Four:

Using Infrared Windows to Reduce the Risk of Arc Flash During Live Thermographic Inspections

Author: Martin Robinson

CEO, IRISS Group

Presented by: Lewis McCormick

Abstract Electrical accidents happen daily, According to the Electrical Safety Foundation, Int'l, 2,000 workers each year in the United States are admitted to burn centers for treatment of severe arc flash burns. While the threat of shock and electrocution from inadvertent contact with energized parts has long been recognized, arc flash and arc blast hazards have only recently been incorporated into the electrical safety standards. There are steps that companies and individuals can take to reduce the occurrence of these accidents and protect everybody concerned from the physical, financial, and statutory consequences related to this type of accident. In the United States the National Fire Protection Association (NFPA) provides a reference for facilities to meet the requirements of electrical workplace safety in its regulation 70E, and outlines the best practices for setting up and maintaining an Electrical Preventative Maintenance (EPM) program in its regulation 70B. One major disadvantage of IR cameras is that they are based on digital camera technology and require a direct-line-of-site to record an accurate image (known as direct temperature measurement), i.e. they can only measure what they can see. In most cases IR surveys are hampered by cabinet designs that obscure the target components being imaged and thermographers are put at risk by having to open cabinets or doors in an attempt to gain access to the internal components that they wish to Inspect.

Introduction NFPA regards systematic and regular thermographic electrical inspections to be a critical part of an EPM program stating that these (thermographic) inspections have uncovered a multitude of potentially dangerous situations. Proper diagnosis and remedial action of these situations have also helped to prevent numerous major losses They can reduce typical visual examinations and tedious manual inspections and are especially effective in long-range detection situations. It goes on to endorse thermographic electrical inspection as relatively inexpensive to use considering the savings often realized by preventing equipment damage and business interruptions (and is)



considered a useful tool to evaluate previous repair work and proof test new electrical installations and new equipment still under warranty. The NFPA 70B standard prescribes routine infrared inspections of energized electrical systems should be performed annually prior to shut down. More frequent infrared inspections, for example, quarterly or semiannually, should be performed where warranted by loss experience, installation of new electrical equipment, or changes in environmental, operational, or load conditions. The standard is also very specific about performing inspections with equipment operating and requires that infrared surveys should be performed during periods of maximum possible loading but not less than 40 percent of rated load of the electrical equipment being inspected. In instances where IR Windows or viewing panes are not available, equipment enclosures should be opened for a view of components whenever possible... since it is not possible for infrared imagers to calculate internal temperatures through standard panel covers or standard materials used in visual inspection panes (i.e. tempered glass or Plexiglas) as these materials are non-transmissive in the infrared spectrum. This unfortunately this requirement goes against NFPA 70E and OSHA who state very plainly that electrical equipment should be de-energized prior to opening

NFPA 70E Originally chartered in 1976 and first released in 1979, the 70E standard is intended for use by employers, employees, and OSHA. Its purpose was to assist OSHA in preparing a set of consensus standards to be used as a basis for evaluating electrical safety in the workplace. Through its nine revisions over roughly 40 years, the NFPA 70E Standard has made an indelible mark on safe work-practices throughout the US and throughout the world, although its greatest impact has only been recognized since the 2000 revisions which included clarification of PPE (personal protective equipment) requirements. Basic compliance with the 2012 edition of NFPA 70E is actually established with a five-step process, which includes an arc flash analysis. The five steps are:

1. Develop and audit on a regularly scheduled basis an electrical safe work practice policy.

2. Conduct an electrical system study to determine the present degree of arc flash hazards and apply associated equipment labeling.

3. Ensure adequate supplies of personal protective equipment (PPE) and proper tools for electrical workers.

4. Conduct regularly scheduled safety training and audits for all electrical workers.

5. Maintain all electrical distribution system equipment and components per manufacturers recommendations.

Hierarchy of Control At the heart of NFPA 70E and OSHA initiatives is the hierarchy of control. Put simply, this concept attempts to control or mitigate risk wherever possible. In



order of preference, the Hierarchy of Control seeks to mitigate risks by taking the following measures in the following order and as determined by the risk assessment:

1. Elimination; the job is redesigned so as to remove the hazard. However, the alternative method should not lead to a less acceptable product or less effective process. If hazard elimination is not successful or practical, the next control measure is:

2. Substitution; replacing the material or process with a less hazardous

one. If hazard substitution is not successful or practical, the next control measure is:

3. Engineering controls; installing or using additional machinery such as

local exhaust ventilation to control the risk. Separating the hazard from operators by methods such as enclosing or guarding dangerous items of machinery. If this method is not effective, the next control measure is:

4. Administrative procedures or safe work practices; an example of

this is to reduce the time the worker is exposed to the hazard. It could also include the provision of training and the performance of risk assessments. Only after all the previous measures have been tried and found to be ineffective in controlling the risks should Personal Protective Equipment be considered.

5. Personal Protective Equipment (PPE);

this is the last control measure to be considered. If chosen, PPE should be selected and fitted to the person who uses it. Workers must be trained in the function and limitation of each item of PPE. PPE may be used as a temporary control measure until other alternatives are installed.

In most cases a combination of engineering controls, administrative procedures and PPE are chosen to effectively control the risks. Where PPE is the main control method it should be (where practical) used in conjunction with another method such as; PPE and safe work practices. In short, the best way to reduce risk is to eliminate it. This is why NFPA 70E and OSHA state very plainly that electrical equipment should be de-energized prior to opening. Realizing that this is not always possible for troubleshooting, inspecting or in situations where shutting down is not viable or poses a risk, there is an allowance made for PPE to be used as a last resort similar to the least preferred method in the hierarchy of control.

NFPA70B



The 70B document also prescribes temperature benchmarking and references the NETA benchmarks as seen in Table 1. The InterNational Electrical Testing Association (NETA) is an organization that serves the electrical testing industry by offering accreditation of third-party electrical testing firms, certifying electrical testing technicians, producing of American National Standards, hosting PowerTest - Electrical Maintenance and Safety Conference, and publishing NETA World technical journal. The NETA table compares temperatures to normal (as determined by a qualified technician) and prescribes a corrective action based on those deviations from normal. It is important to remember that temperature (T) and differential temperatures (T) measurements. The normal temperature is calculated by a qualified technician and will take into consideration many areas of the operation such as load, duty cycles, manufacturers recommendations, risk of failure, age of equipment, historical data relating to failures of similar equipments, etc RCM practices are very useful when determining what an equipments normal operating temperatures and parameters are. Of course, when thermographers and electricians open electrical panels to perform thermographic inspections per NFPA 70B guidelines and insurance requirements, they increase the risk of allowing one of these triggers to occur. NFPA 70E rates the removal of bolted panels on energized electrical equipment to be in the highest hazard/risk category. Consequently, NFPA 70E standards for electrical safety must be adhered to.

Before conducting any maintenance task we must ensure that if possible we eliminate any risks to the maintenance engineers or operators; Personal Protective Equipment (PPE) should always be a last resort. IR Windows eliminate the risks associated with live inspections as they allow an IR Camera direct line of site access to live electrical components without opening an electrical enclosure. As such they provide an excellent means of accessing electrical equipment efficiently and safely as a second qualified person is not

T Range Interpretation Prescriptive Action

1C (1.8F) to

3C (5.4F)

Indicates Possible Deficiency

warrant investigation

4C (7.2F) to

15C (27F) Indicates Deficiency

repairs should be made as time permits

16C (28.8F) and above

Indicates Major Deficiency

repairs should be made immediately

Table 1: NETA benchmarks for temperature and corrective action



required to open and unbolt enclosures and the triggers of arc flash are not introduced as the panels remain closed.

Infrared (IR) Windows IR windows incorporate a specialty lens (typically made of a polymer or crystal) which allow the infrared wavelengths to transmit through the optic, ultimately to be captured and interpreted by an infrared imager or camera. Infrared windows can be installed in the covers or doors of electrical distribution equipment such as switchgear, transformers, MCCs, PDU panels and motor termination boxes to name a few. Because IR windows allow thermographers to perform thermographic inspections while leaving the panel covers and doors closed, thermographers are not exposed to energized conductors and circuit parts. In NFPA terms, the electrical cabinet remains enclosed and the energized conductors and circuit parts are maintained in a guarded condition. The state of the inside of the cabinet, therefore, is not changed and the hazard/risk level is the same as if the thermographer was simply looking through a fixed visual viewing pane or taking a reading from a meter. Ultimately, by utilizing this closed-panel inspection process, companies will eliminate 99% of arc flash triggers during an infrared electrical inspection. Or as stated in NFPA 70E: Under normal operating conditions, enclosed energized equipment that has been properly installed and maintained is not likely to pose an arc flash hazard. Which is why the scope of the PPE requirements in 70E are restricted to electrical safety-related work practices and procedures for employees who are exposed to an electrical hazard Workers who are using enclosed and guarded equipment which is properly operated, properly installed, and properly maintained are not exposed to an electrical hazard and are therefore not required (per 70E) to utilize elevated levels of PPE. However, in the event that the purpose of the inspection is to troubleshoot a suspected fault which could cause an arc flash, then employers and thermographers would be prudent to take all applicable precautions including the use of appropriate PPE, because in most cases closed doors do not provide enough protection to eliminate the need for PPE for instances where the state of the equipment is known to readily change

SUMMARY It is significant that the standards value thermographic electrical inspections as a critical part of an EPM program. IR windows have now provided a way for



companies to comply with the recommendations for inspection processes, while complying with the mandates for arc flash avoidance. IR windows are not a protective device and no IR window on the market is as structurally sound as the steel which is so easily ripped apart in un-vented blast. They are intended to maintain a separation between thermographer and energized components and thereby eliminate the increased risk of the thermographer or other workers triggering an arc flash. Infrared windows offer companies and thermographers a safer, more efficient way to perform an inspection while maintaining an enclosed and guarded condition for the energized conductors and circuit parts, while preserving a steady-state inside the cabinet. This closed-panel inspection process will eliminate the increased level of risk associated with open-panel inspections, and eliminates the requirement for elevated levels of PPE. An article in insights magazine by Joseph Weigel states that Schneider Electrics North American Operating Division can attest first hand to the benefits of an effective EPM. Since 2003, the company has seen its medical incident rate drop by 72 percent in its North American facilities. That translates to a savings of approximately $10 million in workers compensation savings for the 2010 calendar year. Complying with the NFPA standard practices and utilizing technologies such as IR windows allow companies to really show how much they value their workforce by maintaining a safe working environment, this has additional spin-offs in increased employee morale and reduced absenteeism, by providing the tools, training and maintenance programs to reduce the chances of injury in their workplace. Thats a reputation for which any company would delight in.

References

NFPA 70 - National Electrical Code (NEC), 2011 Edition

NFPA 70E - Handbook for Electrical Safety in the Workplace, 2012 Edition

NFPA 70B - Recommended Practice for Electrical Equipment Maintenance, 2013 Edition

IEEE 902-1998 Guide for Maintenance, Operation and Safety of Industrial and Commercial Power Systems

ANSI/NETA MTS-2007 - Standard for Maintenance Testing Specifications for Electrical Power Distribution Equipment and Systems

ANSI Z10-2005 - Occupational Health and Safety Management Systems

ISO 14001: 2004 - Environmental Management System

OHSAS-18001-2007 - Occupational Safety and Health Management Systems Requirements

ILO-OSH 2001 - Guidelines on Occupational Safety and Health Management Systems

CSA Z1000-2006 - Occupational Safety and Health Management



Insights Article-2010 Joseph Weigel Avoid Devastating Electrical Arc Flash Accidents

Documents

Session 4 Lewis McCormick Paper FINAL