A probabilistic approach to safety design: the two-element environment

The immediate electrical surroundings of the hospitalized patient are comprised of elements which may or may not be powered by electricity. Four electrical "operators"--G, E, T, and C--indicate respectively the status of the grounding of elements, the electrical leakage of elements, the electrical contact of one element with another, and the electrical contact of the patient with the elements. The operators are considered as mutually stochastically independent indicator random variables. The operators are utilized to formulate the probability of electrical danger in a basic environment of 2 elements. Grounding concepts of electrical safety are questioned as the operators, when supplied with probabilities, demonstrate a range of situations over which an ungrounding strategy may provide more safety than one of grounding. The probablisitic model calls for the collection and analysis of electrical data from which estimates of probabilities may be obtained and with which electrical models may be refined.