7.1 When to test
As discussed at paragraphs under 5.6 above, user organisations should design and implement electrical safety inspection and test regimes on the basis of risk assessments.
In practice, most user organisations have found it necessary to carry out electrical inspection and safety testing on medical electrical equipment on the following occasions.
- On newly acquired equipment prior to being accepted for use
- During routine planned preventative maintenance.
- After repairs have been carried out on equipment.
A patient should never be connected to a piece of equipment that has not been checked.
The testing regime used in the case of acceptance testing will be slightly different to that used on other occasions particularly as regards checks on the condition of packaging, presence of relevant documentation and accessories. However, it is useful to use the acceptance testing procedure to lay down baseline data for comparison when the equipment is tested on future scheduled services and after repairs.
7.2 Example inspection and test protocol
Annex 3 contains a test record sheet that is used to record inspection and test results produced by a simple electrical safety protocol. It is not intended to be in any way prescriptive, but is included here simply to illustrate many of the important features of an effective protocol.
Details of the equipment under test are recorded at the top of the form including the device serial number and a plant number ascribed by the user organisation. This ensures that the record can be linked to the particular item of equipment. The class and type/s of the equipment under test are also recorded here to ensure that appropriate test limits are applied.
The details of the test equipment used are also recorded at the top of the form together with the calibration date. This information is important for traceability since test results can only be proved to be accurate if it can be demonstrated that the test equipment was in calibration.
The visual inspection checklist provides a record that the relevant parts of the equipment have been inspected. This is very important since, in practice, the visual inspection is likely to flag up problems far more often than the electrical safety tests themselves. It is also important that a record of visual inspection is kept. Where user organisations use electronic means to record data downloaded from electrical safety testers, it is important to add information on visual inspection to the record.
The electrical safety tests that are used in this particular protocol are few in number and are the same tests, derived from IEC60601-1, that were selected for HEI 95. The earth continuity test is obviously important for all class I equipment. The insulation test is intended to look at the insulation between the mains part and the earth of the equipment under test, and may be regarded as a pre-test to verify that it is safe to apply mains power in order to measure leakage currents.
Earth leakage current here is only measured under normal condition (NC). Note that "normal" and "reverse" here mean that the leakage current is measured with L1 and L2 the right way round and the wrong way round. Both of these conditions are defined as "normal condition". This test will not usually produce as high a reading as if the test is conducted with under single fault condition, neutral open circuit. However, in most cases, if there is no problem with earth leakage current under normal condition, there is unlikely to be one under the single fault condition.
Enclosure leakage and patient leakage currents are both recommended under this protocol to measured under single fault condition, earth open circuit (EOC). The rationale behind this is that any problems are likely to be evident under this condition and it is not improbable that the fault condition may arise when the equipment is in use.
At the foot of the form, it is recorded whether the equipment has passed or failed in the light of the visual inspection and the electrical safety test results. The date of the test and the identity of the person who performed the test must also be recorded.
The comments field below the table is a useful feature of any recording system. It allows any observations to be recorded, for example, of peculiarities of the equipment under test or concerns about test results. The record should be referred to by the person performing the next test and inspection on the equipment prior to carrying out the inspection and test.