Biomedical Inspections

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Electrical Safety Inspections: - The origins of the Standardized Electrical Leakage Tests goes back to the early days of electrical equipment in the Operating Room. It was found that while a single device such as an electrocardiograph, exhaustively tested by itself and found to be “safe”, when used in combination with say a motor-driven aspirator; by itself also tested to be “safe”, the combination of the two could prove to be lethal. When this was researched, it was found that each piece of equipment “leaked” a minute amount of electricity, which, because the patient was thoroughly grounded and especially vulnerable due to the sub-coetaneous operation, added up to become a dangerous dose of electrical current. Underwriter’s Laboratories pioneered the study of this matter and wrote Standards limiting the maximum amount of ‘Electrical Leakage’ that should or could be allowed for Medical Equipment under various situations. Today almost all cord-connected equipment use a third wire cord and plug to “drain” any “leakage” safely to ground. There remain however, two concerns that are especially important in a medical environment where multiple devices may be used in relation to a particular patient. First – since the third wire is part of a flexible cord and subjected to wear and tear – what if the third wire alone fractured? In this case all of the “leaked” electricity might now seek a path through the patient and there would be no appearance of any problem since the remaining two wires would still activate the machine. The second concern follows the first: In such a case, how much would the maximum allowable “leakage” be? The answer was to specify a maximum allowable amount of current (usually less than 100µ amperes) for various classes of Medical Equipment, and to require that all cord-connected Patient Equipment and Outlets be inspected regularly to assure correct polarity and that multiple bad cords was a statistical impossibility. This is the reason that Electrical Safety Inspections have become institutionalized.