Many electrical safety tests are performed under single fault conditions such that a means for protection against electric shock has been removed. In the case of patient leakage current with mains on applied parts, a hazard is actually introduced.


Even under normal condition, the equipment under test cannot be regarded as safe, since the supplementary protection may have been compromised by the test arrangement. For these reasons no equipment under test should be touched whilst tests are being undertaken, as parts of the equipment may be hazardous live. For similar reasons, tests should be conducted on suitable non-conductive surfaces and conductive objects should be kept well clear of the equipment.


The potential hazard is exacerbated by the use of automatic testers when running in automatic or semi-automatic modes since hazardous voltages may appear on the equipment under test at any time without any warning. Where it is not possible to remove equipment to a workshop facility for testing, particular care must be taken to ensure that there is no possibility of any other persons coming into contact with the equipment under test.


Many categories of medical electrical equipment can produce outputs for treatment purposes that, if applied incorrectly to a person can prove fatal, or at least cause serious injuries. Examples of these categories include surgical diathermy machines, nerve and muscle stimulators, short-wave therapy units and defibrillators. Persons who have not had specific training on such equipment sufficient to enable them to avoid the hazards should not be allowed to perform electrical safety testing on it.


The tests applied in the course of routine safety testing can cause damage to equipment if carried out incorrectly or inappropriately. Such damage may lead directly or indirectly to patient injuries or death if the equipment is put back into service in this condition. It is clear that only maintenance personnel who are sufficiently trained to avoid such occurrences arising should carry out electrical safety testing of medical equipment.




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