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The Case of the Misleading Meter

Dec 1, 2007 12:00 PM, By John A. Palmer, Ph.D., P.E., C.F.E.I., Knott Laboratory, LLC

In my mind, the biggest problem was that the high-voltage meter he used did not have any labeling or other marking on the display indicating that the displayed units were in kilovolts, although a small sticker on top of the unit (not visible during use) did state that the display was in fact showing kilovolts. In my opinion, if the meter in question had included a clear indication of the units associated with the displayed value, the victim could have easily seen and understood that the terminal to which he was about to connect the ground cable was indeed energized.

Although lockout/tagout (LOTO) procedures were under way at the time of the incident, they would not have de-energized the terminal Electrician A contacted. In placing a safety ground to avoid the potential for inadvertent energization of the portions of the system being worked on, Electrician A was implementing steps associated with LOTO. Furthermore, by using the three different voltage-sensing devices, he was exercising reasonable prudence to ensure safety in his activities. Therefore, I asserted that Electrician A believed the terminal to be de-energized because he misinterpreted the reading of the high-voltage meter.

Upon further investigation, I also uncovered that the victim had followed training requirements as outlined in NFPA and OSHA standards, and was qualified to perform the work he had been assigned. He had presumed the parts to be energized until he had verified the system had been de-energized, as required by OSHA and NESC. Similarly, he was wearing gloves and goggles, but did not have the arc flash personal protective equipment (PPE) that would have been prescribed for work on energized equipment — because he believed he had already verified it to be de-energized.

The lesson

In this case, it is unreasonable to argue that the nature of the equipment speaks for itself because someone taking measurements should automatically know what he is measuring. The fact is that there are a number of different measurements an electrician might be making. For example, a high-voltage power system can have measurements of voltage (or kV), current, wattage, reactive power, or electric field intensity. An electrician may also have an interest in knowing temperatures of specific components, rotational speed of electric motors, resistance, inductance, or capacitance. On any given day, an electrician may use several of a wide array of different meters. This is the very reason it's standard practice to indicate units on the display of the meter, thus avoiding any potential ambiguity in the interpretation of results.

Ultimately, I concluded that the victim's reliance on safety protocols and procedures was trumped by a defect in his high-voltage meter, which could have been fixed with a very simple modification to the equipment design. The resultant lawsuit settled for an undisclosed amount before the case went to trial.

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Palmer, Ph.D., P.E., C.F.E.I., is manager of electrical engineering and fire investigations at Knott Laboratory, LLC, Centennial, Colo.

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