Performing proper calculations to determine the magnitude and duration of touch voltages in the event of a ground fault is paramount for the protection of persons against electric shock. The analysis of magnitudes and durations of touch voltages in cable installations can provide electrical professionals with a better understanding of the requirements of Art. 250 of the NEC regarding the protection against electric shock. Such analysis disproves a common misconception held among many electrical professionals that providing an installation with a proper ground electrode is a sufficient condition to eliminate electric shocks in the event of a fault. In reality, even in correctly designed and erected installations, the risk of electric shock does exist, and its magnitude can be quantified through the study of touch voltages.
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