After reading the Forensic Casebook article in the December 2007 issue, I believe the author, Mr. Palmer, is incorrect on several statements.
NFPA 70E clearly states that workers must first lockout/tagout (LOTO) equipment or systems — and the equipment or system is not considered de-energized until a test for no-voltage is completed. The author seems to have this task reversed.
NFPA 70E also states while conducting the test for no-voltage, the worker must assume all equipment or systems are energized and use the appropriate personal protective equipment (PPE), such as FR clothing, rubber insulating gloves with leather protectors, face shield, hard hat, etc.?Mr. Palmer implies the victim did not need to wear PPE while conducting the test for no-voltage because he assumed the equipment or system was locked out and tagged out.
Any properly trained or qualified electrical worker knows that a “TIE” circuit breaker compartment could contain six energized ports or stabs, not three. Such a worker would know that unless both “buses” were isolated, the ports or stabs would be energized. The author excuses the victim's actions by stating that he may have assumed he was in a different CB compartment.
Anyone authorized or qualified to use voltage testing instruments, especially high-voltage detectors or meters, knows that these pieces of equipment typically do not indicate or detect voltage less than 1,000V. Also, most meters (except the new automatic reading kind) do not literally indicate the magnitude — this is interpreted by the user when selecting the appropriate range and again interpreted while reading the display. If the victim had performed the required and standard practice of testing the instrument to prove it is indicating properly before and after conducting the test on the equipment or system, he would have realized the meter was in fact working properly. Mr. Palmer ignores the test before and after, leading readers to believe meters display?more than they actually display. He also excuses the improper use of the “squawk box” detector.
The author also ignores another dangerous task performed by the victim. Workers should never use a low-voltage meter rated up to 600/1,000V on a medium- or high-voltage system, unless they have proven without a doubt that a medium or high voltage is not present.
My final comment is regarding the application of ground cables (temporary protective grounds). For many years, I have questioned the benefit versus risk of using temporary protective grounds. This case affirms my belief that more workers are killed applying or failing to remove temporary protective grounds than workers are saved by these cables. Salisbury and A. B. Chance have had available videotapes and information proving that unless workers use “equipotential grounding” techniques (which the victim was not preparing to perform), the temporary protective grounds will not prevent electrocution.
I believe the workers involved in this incident were not adequately trained or qualified to perform the required tasks. I also believe this article does not address the root causes of this event. Consequently, it will happen again and again, especially if we accept the author's findings.
— John Kaldon, president, Broad Run Consultants, Ltd., Coatesville, Pa.
Author's reply: Thank you for your thoughtful and well-considered discussion regarding my article. As with most electrical accidents, there is a range of contributing factors that leads to the initiation of such events and the severity of resultant damage. Because of constraints on time and space, as well as to preserve the anonymity of the interested parties, it was impractical to include every detail of the incident. The primary objective of my article was to alert electricians that they must be aware of the limitations of their test equipment, and alert manufacturers of test equipment of the potential dire consequences of cutting very simple corners.
While I chose (in the limited space of my article) to focus on the confusion related to the meter output and the perceptions of the victim, you are correct to observe that safety procedures exist that, had they been followed precisely, would likely have prevented or reduced the severity of the injuries sustained. By focusing on some of the unique circumstances of this particular incident, it's certainly not my intent to imply that the victim bore no responsibility. In nearly every electrical accident, some measure of responsibility lies with the controlling electrician. Nevertheless, the manufacturers who choose to ignore industry practices and safety standards must be held accountable for their decisions that result in a catastrophic loss or injury.
In the subject incident, the victim had received communication that the relevant portions of the switchgear had been previously locked out and tagged out by other personnel. He was verifying the status and applying safety grounds as a follow-up to the LOTO procedure. As you indicate, NFPA 70E does require that for the application of safety grounds, appropriate PPE should be worn, including a multilayer flash suit. His choice to apply the ground without the appropriate PPE is explained (but certainly not excused) by his belief that the equipment was de-energized. His confusion about which cubicle he was working in is not uncommon when manufacturers and owners do not clearly label the equipment and provide appropriate warnings (see “Forensic Casebook” on page 14 of the January 2006 issue).
In commenting what “anyone qualified knows,” the assumption is made that in the urgency of the moment one may logically assess the information to come to a proper conclusion. One of the key principles of human factors is that ambiguity should not rely on reasoning for resolution. The manufacturer's failure to provide clear labeling on the display is not excused by the operator's failure to reason through the possible meanings of information provided on the display.
Your observation about the hazards of the application of protective grounds is interesting and deserves serious consideration for future amendments to the codes and standards. Of course, it would be unfair to hold a victim to account for not following a practice that has not yet won industry consensus. I would certainly encourage you to continue pursuing that line of inquiry.
I recognize certain safety procedures were bypassed and that those actions contributed to the accident. In the article, I highlighted other issues that also contributed to the accident. It is certainly my hope that the article is a reminder of the importance of following safety protocols, while making the reader aware of specific issues related to test equipment about which they may not have previously been aware. Thank you for your interest.
— John Palmer, Ph.D., P.E., C.F.E.I., manager, electrical engineering and fire investigation, Knott Laboratory, LLC, Centennial, Colo.
In “The Case of the Misleading Meter,” I find it interesting that Mr. Palmer states, “Upon further investigation, I also uncovered that the victim had followed training requirements as outlined in NFPA and OSHA standards…” However, he appears to overlook the following requirement in OSHA 1910.333(b)(2)(iv)(B):
“A qualified person shall use test equipment to test the circuit elements and electrical parts of equipment to which employees will be exposed and shall verify that the circuit elements and equipment parts are de-energized. The test shall also determine if any energized condition exists as a result of inadvertently induced voltage or unrelated voltage backfeed, even though specific parts of the circuit have been de-energized and presumed to be safe. If the circuit to be tested is more than 600V nominal, the test equipment shall be checked for proper operation immediately after this test.”
No mention is made of the electrician (victim) proving the proper operation of the test instrument. Had the instrument been properly tested, it should have at least raised the awareness in the electrician's mind that further investigation was warranted before proceeding to apply a temporary grounding conductor.
— C. Mark McClung, electrical specialist, Dow Chemical Co., Charleston, W. Va.
Author's reply: The cited passage of OSHA, which is similar to the wording in NFPA 70E, requires that the circuit elements be tested to verify that the circuit is de-energized, which is what the victim did. OSHA and NFPA also require that “the test equipment shall be checked for proper operation immediately after the test.” While this is frequently interpreted to mean that the equipment should be tested on a known source, there is some ambiguity in the wording because a known source is not always readily available at the location where the equipment is being used. I am unaware, specifically, whether any action was taken by the victim to check for proper operation, but your observation that such a test may have raised his awareness of the hazard that was present certainly seems correct, if the method of checking for proper operation was specifically to apply the instrument to a known source. Nevertheless, there is no question of whether or not the equipment was functioning properly, only that the meaning of the output was unclear, so checking for proper operation by a means other than a known source would not have necessarily prevented the situation.
— John Palmer, Ph.D., P.E., C.F.E.I., manager, electrical engineering and fire investigation, Knott Laboratory, LLC, Centennial, Colo.