Electrical Safety Myths and Facts

Transcription

1 Electrical Safety Myths and Facts Copyright Material IEEE Paper No. ESW James R. White Senior Member IEEE Shermco Industries, Inc.2425 E. Pioneer Drive Irving, Texas Abstract This paper reviews some of the more common electrical safety myths and misconceptions field electrical workers often have. Many of these misconceptions continue in spite of training and education. Some are handed down from worker to worker, similar to tribal knowledge. The real danger from these misconceptions is that they impede the truth and cause electrical workers to misjudge hazards and risks. Index Terms Myths, misconceptions, electrical safety, electrical shock, equipment grounding, NFPA 70E, OSHA. I. INTRODUCTION In speaking with electrical workers over the years, it is apparent that some well-educated and smart people have long-held, and virtually unshakable, myths and misconceptions concerning electricity. Since a large percentage of the field electrical work force have learned their trade on the job, they will often have holes in their knowledge base, causing misunderstandings and possible unsafe attitudes towards electricity and electrical work. This paper reviews some of the more common myths and misconceptions electrical workers may have concerning electricity and electrical safety. Readers are encouraged to use all or parts of the presentation as considered necessary to enlighten field workers and possibly prevent accidents that may be caused by them. II. NFPA 70E: THE BOOK NO ONE READS Almost true. It seems that very few take the time to read NFPA 70E Chapter 2, Safety-Related Maintenance Requirements (1). The sad thing is, Chapter 1, which everyone uses, has considerably less value if the requirements in Chapter 2 are not met. Electrical system equipment must be properly engineered, properly installed and properly maintained in order for the requirements in Chapter 1 to be met. Chapter 2 provides the bare minimum requirements. Chapter 2, Section 205 has such requirements as: Single-Line Diagram. A single-line diagram, where provided for the electrical system, shall be maintained in a legible condition and shall be kept current General Maintenance Requirements. Electrical equipment shall be maintained in accordance with manufacturers instructions or industry consensus standards to reduce the risk of failure and the subsequent exposure of employees to electrical hazards Overcurrent Protective Devices. Overcurrent protective devices shall be maintained in accordance with the manufacturers instructions or industry consensus standards. Maintenance, tests, and inspections shall be documented. Even though not mandatory, the annexes provide additional information on the reasoning behind some of the more difficult sections in NFPA 70E and much more detail. III. THE GRENADE THEORY The incident energy is so high you can t even walk into the powerhouse without PPE. Another common misconception is You need arc flash PPE to just walk through a room with operating electrical equipment. I ve received phone calls from engineers saying I don t care about electrical safety because I don t think it s necessary to wear arc-rated PPE whenever a worker is near energized equipment. Their viewpoint is that it is a possibility that the equipment could fail. Could it fail? Certainly. The risk, however, is very small and, even though it should not be ignored, it does not create the need for arc-rated PPE, unless you are interacting with the equipment in a manner that could cause failure. Reference NFPA 70E Section 130.7, Informational Note No. 2, It is the collective experience of the Technical Committee on Electrical Safety in the Workplace that normal operation of enclosed electrical equipment, operating at 600 volts or less, that has been properly installed and maintained by qualified persons is not likely to expose the employee to an electrical hazard. Electrical equipment rated under 600 volts that has been properly installed in accordance with the NEC and all related codes and standards and has been properly maintained does not present an electrical arc flash hazard, unless it is operated in a manner that could cause failure. Reference NFPA 70E Section 100, definition of an Arc Flash Hazard, which states, A dangerous condition associated with the possible release of energy caused by an electric arc. Informational Note No. 1: An arc flash hazard may exist when energized electrical conductors or circuit parts are exposed or when they are within equipment in a guarded or enclosed condition, provided a person is interacting with the 1

2 equipment in such a manner that could cause an electric arc. Under normal operating conditions, enclosed energized equipment that has been properly installed and maintained is not likely to pose an arc flash hazard. Informational Note No. 2: See Table 130.7(C)(15)(a) and Table 130.7(C)(15)(b) for examples of activities that could pose an arc flash hazard. The types of activities specified in NFPA 70E Table 130.7(C)(15)(a) are inserting and removing (racking) circuit breakers and inserting and removing MCC buckets. Both of these tasks involve making and breaking load bearing electrical contacts without the benefit of arc extinguishers. IV. THE GRANDFATHER EXCEPTION Everyone wants to be exempted from something. Being grandfathered in is a great idea! Often heard is the statement, We are exempt from 70E, we were built before the standard was written or We follow the 2004 (or some earlier) edition of NFPA 70E. The problem is, there is no such exemption. NFPA 70E is not like the NEC, where once the facility is constructed under the current codes and standards it does not require updating, unless the facility undergoes a major renovation. NFPA 70E is a safe work practice standard, which continually evolves. Reference NFPA 70E page 1, where it states,.it was issued by the Standards Council on August 11, 2011, with an effective date of August 31, 2011, and supersedes all previous editions. Once the revised edition of NFPA 70E is issued, previous editions are no longer effective. The NEC contains the same language, but has a different meaning. With the NEC, since it is a code that is enforceable, it supersedes the previous edition, but is not retroactive. It is one of the differences between a code and a safe work practice. V. QUALIFIED BY EXPERIENCE As with many myths and misconceptions, this one has an element of truth. Heard mostly from long-time (read that as older) electrical workers, they believe their years of experience count for something. Well, actually for everything. The problem is, OSHA and NFPA 70E don t agree with that concept. The idea that 15, 20 or even 30 years of field experience makes a worker qualified is exposed as a falsehood by the statistics. In a paper presented at the 2004 IEEE/IAS Electrical Safety Workshop (2), it was revealed that the workers most often injured were laborers with less than two years of experience and maintenance personnel and supervisors with more than ten years of experience. Figure 1 is a slide from that presentation. Figure 1 Workers Involved in Most Accidents OSHA defines a qualified person in 29CFR , which states, One who has received training in and has demonstrated skills and knowledge in the construction and operation of electric equipment and installations and the hazards involved. There are two parts to satisfy, technical skills and knowledge and safety skills and knowledge. Both must be demonstrated. Whereas the technical skills portion may be accomplished through apprenticeships, degrees and field experience the safety side must be accomplished through training and a demonstration of those skills. NFPA 70E has a similar definition for a qualified person, One who has skills and knowledge related to the construction and operation of the electrical equipment and installations and has received safety training to recognize and avoid the hazards involved. Both OSHA and NFPA 70E further define what constitutes a qualified person in OSHA regulation 29CFR and.333(c)(2) and NFPA 70E Section 110.2(D). A degree, license, job position or permit in no way qualifies an electrical worker in OSHA s eyes. Note that both OSHA and NFPA 70E require specific safety skills and knowledge in order to be considered a qualified person. Being qualified is a two-part requirement technical skills and knowledge and safety skills and knowledge. VI. ONLY PEOPLE WITH ELECTRICIAN IN THEIR TITLES NEED TRAINING OSHA does not look at a job title to determine whether they require electrical safety training; they look at whether they are exposed to electrical hazards. Table S-4 in 29CFR specifically calls out electricians and welders, but also carries the statement that anyone who is exposed to the hazard will also require training. The level of training will depend on their job tasks and risks to the hazards. Specifically, OSHA states, The training requirements contained in this section apply to employees who face a risk of electric shock that is not reduced to a safe level by the electrical installation requirements of through Note: Employees in occupations listed in Table S-4 face such a risk and are required to be trained. Other employees who also may reasonably be expected to face comparable risk of injury due to electric shock or other electrical hazards must also be trained. 2

3 Workers who most probably require qualified person training include HVAC technicians, I&C technicians, multicraft employees; anyone who is exposed to voltages above 50V. VII. HOSPITALS KNOW EXACTLY WHAT TO DO FOR ELECTRICAL SHOCK VICTIMS Probably not. Emergency rooms physicians see hundreds, if not thousands of cases each year from vehicle accidents, domestic disputes, gang activity and home accidents that result in broken bones, cuts, lacerations, contusions, concussions, gun shots, and other types of non-electrical injuries. Electrical shock victims are not nearly as common, so when one arrives in the ER, the attending physician may need some help. Dr. A.G. Soto has recommended a onepage (front and back) form (3) to both gather important information concerning the accident and victim (if possible) and to provide some basic information on electrical shock effects and how to manage them. VIII. USE CONTRACTORS FOR ALL HAZARDOUS WORK This is true up to a point. Certainly, if you don t have the in-house expertise, contracting work out is a viable alternative. However, contracting work out does not absolve your company of liability should an accident occur. OSHA s Multi-Employer Worksite Policy CPL Rev ensures that in all cases the Host employer (equipment or facility owner) will be held at least partially responsible. This policy, in effect since 1999, allows OSHA to split responsibility for an accident in four roles: Controlling employer Exposing employer Correcting employer Creating employer. OSHA will determine if your company should be assigned one of these roles, then determine if you fulfilled your responsibilities for that role. Citations follow soon after. NFPA 70E also contains requirements regarding both the Host and contracting employers in Section Section 110.1(C) requires the pre-job planning meeting be documented. IX. I VE GOT EVERYTHING LABELED Figure 2 shows a typical arc flash hazard warning label as required by the NEC Section (4). The label in Figure 2 actually has more information than that required by , as it only is required to warn against the arc flash hazard. [Type a quote from the Figure 2 Typical Arc Flash Hazard Warning Label The wording in the NEC is mirrored in NFPA 70E Section 130.5(C), Equipment Labeling. Electrical equipment such as switchboards, panelboards, industrial control panels, meter socket enclosures, and motor control centers that are in other than dwelling units and are likely to require examination, adjustments, servicing or maintenance while energized shall be field marked with a label. In addition, NFPA 70E also requires the following information not required by the NEC: containing all the following information: (1) At least one of the following: a. Available incident energy and the corresponding working distance. b. Minimum arc rating of clothing. c. Required level of PPE. d. Highest Hazard/Risk Category (HRC) for the equipment. (2) Nominal system voltage (3) Arc flash boundary NFPA 70E requires this additional information because it is clear that electrical workers are not able to determine appropriate PPE requirements as mandated by 29CFR This is most often due to the information not being readily available. For those who appreciate exceptions, there is an exception for this requirement in NFPA 70E, Exception: Labels applied prior to September 30, 2011 are acceptable if they contain the available incident energy or required level of PPE. The method of calculating and data to support the information for the label shall be documented. X. OSHA WON T COME AFTER ME In general, OSHA does not pursue individuals; they fine companies. However, if you are responsible for someone s death, through a decision or policy you implemented, that can all change. The information in Table 1 is from the OSHA website: 3

4 Criminal Referrals Table 1 Referrals or Significant Aid to Prosecutors Addressing OSHA-Related Matters These actions include referrals under Title 29 of the United States Code, Section 666(e), for employee deaths caused by willful conduct violating an OSHA standard, obstruction of justice, state and local investigations and prosecutions, and fraud related to other OSHA matters, such as training verification. Ten to 14 cases a year may not seem like a large number, especially compared to the thousands of cases OSHA prosecutes. That is, unless you happen to be one of those being charged. Note also that these criminal referrals also include obstruction of justice and fraud, such as altering training records. Oh, now I see why I should have been spending that money to train my people. Too late! disregarded as harmless, but also should be used to instruct new electrical workers as to the real hazards of their jobs. Also note that this is for hand-to-foot contact and other types of contact could have a lower body resistance, allowing more current to flow through the body. XIII. LOW-VOLTAGE MEANS LOW ARC FLASH HAZARDS I wish I had a nickel for every time I ve heard, It s just low voltage or It s just 208V, 480V or some other voltage. The fact of the matter is, the arc flash hazard can exist even as low as 208V; it just requires a large short circuit source. At 480V there is more than enough voltage to push current through the arc (7). Figure 3 is from the infamous TEST NUMBER 4 (8) conducted at a fuse manufacturer. In that test the line-side of a 480V 30A circuit breaker was shorted to ground, simulating a phase-to-ground short circuit. There was 22,000A available short circuit current with an operating time of 6 cycles. The incident energy was estimated at 5.8 cal/cm 2. It s amazing what 5.8 cal/cm 2 will do to a person! XI. OSHA ENFORCES NFPA 70E OSHA cannot enforce anything but Federal regulations. That confines them to writing citations for violating 29CFR1910 (General Industry) or 29CFR1926 (Construction) regulations. In a letter of interpretation (5), OSHA states, Industry consensus standards, such as NFPA 70E, can be used by employers as guides to making the assessments and equipment selections required by the standard. Similarly, in OSHA enforcement actions, they can be used as evidence of whether the employer acted reasonably. Federal courts have found that NFPA 70E is standard industry practice. OSHA may not be able to enforce NFPA 70E, but they can certainly use it against you. XII. IF YOU TOUCH A 20A CIRCUIT BREAKER, YOU LL HAVE 20A FLOW THROUGH YOUR BODY I actually heard a foreman telling a group of apprentices this while I was at a job site. Maybe he knew better and was trying to scare them into complying with safety rules, or maybe he didn t know the truth. This is similar to a safety instructor I once heard tell students that 3mA of current directly across a person s heart would kill them. Statements such as these may achieve the desired effect initially, but once the person who hears such misinformation gets the truth, credibility is gone forever. Only the current allowed by OHM s Law would flow through a person. That current is dictated by the voltage divided by the resistance of the body. That resistance is generally recognized to be about 1,000Ω (6) for the average man. There are factors that will tend to modify that value up or down, such as bone mass, walking surface, shoe material, wet environment, etc., but is a fair number to begin with. At 120V and having 1,000Ω resistance in the circuit, current flow would be limited to a maximum of 120mA. This value of current could certainly be lethal and should not be >225 0 C/437 0 F Figure 3 Test Number Four Results XIV. ONE SIZE FITS ALL PROTECTION At more than one facility I ve heard safety managers state that they bought 100 cal/cm 2 arc-rated flash suits and that was all they would allow their workers to use! This must be from the more is better philosophy of protection. Referencing 29CFR , OSHA states, Employees working in areas where there are potential electrical hazards shall be provided with, and shall use, electrical protective equipment that is appropriate for the specific parts of the body to be protected and for the work to be performed. Wearing too much protection can be as hazardous as too little, if it interferes with performing the task. The other aspect is that of the arc blast hazard. Yes, a person can be protected from the thermal hazard, but at those levels there s a good chance the arc blast hazard will be a greater hazard than the thermal hazard. NFPA 70E Section 130.7(A) Informational Note No. 1 states, The PPE 4

5 requirements of are intended to protect a person from arc flash and shock hazards. While some situations could result in burns to the skin, even with the protection selected, burn injury should be reduced and survivable. Due to the explosive effect of some arc events, physical trauma injuries could occur. The PPE requirements of do not address protection against physical trauma other than exposure to the thermal effects of an arc flash. At this time we are not able to accurately estimate the arc blast hazard. This means that when working on or near energized electrical equipment that has a high short circuit available current extra caution is required. XV. THE GROUND WIRE DOESN T REALLY DO ANYTHING It is surprising how many electricians believe this is true. I have found electricians using the ground wire as another energized conductor, as neutral and, in numerous instances, just cutting it off. This results in fires, injuries and fatalities. Proper grounding and bonding, as required by the National Electrical Code is critical to worker safety, but people continue to cut ground pins off or use cords that have broken ground pins, disconnect grounds or ignore grounding requirements, all to their harm. XVI. CONCLUSIONS Information is one extremely important part of electrical safety. Misinformation can undue years of work and damage credibility to the point that nothing that is said further will correct the problem. Workers exposed to electrical hazards must have accurate information in order to make acceptable and safe decisions when working in the field. One of the most important aspects of NFPA 70E is that it requires an electrical system to be properly engineered, installed and maintained. If these three requirements are not met in accordance with NFPA 70E Chapter 2, the requirements of Chapter 1 would very difficult to apply. Chapter 2, and to a lesser degree Chapter 3, are critical to maintaining a safe work environment as mandated by OSHA 5(a)(1), General Duty Clause. XVII. REFERENCES 1. NFPA 70E, Standard for Electrical Safety in the Workplace, 2012 edition, Chapters 1 and 2 2. Kowalski-Trakofler, Ph.D. Kathleen, Non-Contact Electric Arc-Induced Injuries in the Mining Industry; a Multi-Disciplinary Approach, 2004 IEEE/IAS Electrical Safety Workshop 3. Soto, A.G. MD., Electrical Injuries Management, 2004 IEEE/IAS Electrical Safety Workshop 4. NFPA 70, National Electrical Code, 2011 edition. Pg Letter of Interpretation, OSHA, General Duty Clause (5)(A)(1) Citations on Multi-Employer Worksites; NFPA 70E Electrical Safety Requirements and Personal Protective Equipment, ANSI/IEEE, Guide for Safety in AC Substation Grounding, Std , pg Lee, Ralph H., The Other Electrical Hazard, Electrical Arc Blast Burns, IEEE Transactions on Industry Applications, volume I-A-18, No. 3, May/June Ray Jones, PE, Danny Liggett, Mary Capelli- Schellpfeffer MD, Terry Macalady PE, Lynn Saunders PE, Robert Downey PE, Bruce McClung PE, Arthur Smith PE, Shahid Jamil PE, Vincent Saporita PE, Staged Tests Increase Awareness Of Arc-Flash Hazards In Electrical Equipment, 1997 IEEE PCIC Conference, Paper PCIC-97-xx XVIII. VITA James White is the Training Director for Shermco Industries, Inc. located in Irving, Texas. He is a Senior member of the IEEE, the recipient of the 2011 IEEE/PCIC Electrical Safety Excellence Award, the 2008 IEEE Electrical Safety Workshop Chairman, Alternate international Electrical Testing Association (NETA) representative on NFPA 70E, Primary representative on NFPA 70B, and is the NETA representative to ASTM F18. James is also a certified Level IV Senior Substation Technician with NETA, an inspector member of IAEI and serves on the NETA Safety and Training Committees. James is the author of Electrical Safety, A Practical Guide to OSHA and NFPA 70E and Significant Changes to NFPA 70E 2012 Edition both published by American Technical Publishers. 5