The underlying principal for frequency of testing is that the duty holder (i.e. the person with the equipment "within their control") with the advice of the test company and or competent person, when necessary must assess the need for testing the equipment against the following:
The environment – Equipment in a benign environment is likely to suffer less damage than equipment in an arduous environment.
The users – If users report damage promptly hazards will be avoided. Conversely, if equipment is likely to receive unreported abuse, more frequent inspection & testing is required.
The equipment construction – The safety of Class 1 equipment is dependent upon a connection with earth. Class 2 equipment is not dependent upon a fixed earth.
The equipment type – Appliances that are hand-held are more likely to be damaged than fixed appliances.
Re-test frequency can be as long as 4 years and as little as 3 months and sometimes before use (hire equipment) the overwhelming majority of business's and organisations base there test regime on an annual test (depending on equipment requirements) as the most practical and safe approach to there testing program.
The following table provides guidance on the initial frequencies of inspection & testing as per the Code of Practice for In-Service Inspection and Testing of Electrical Equipment and our own experience. However, the frequency must depend upon the factors listed above and should be kept under constant review.
Equipment Class types
Electrical appliances are differentiated by a series of IEC protection classes. In PAT Testing it is essential for the person PAT Testing to know the difference in classes and therefore what checks must be completed before declaring the item electrically safe.
Class I - Single insulated wiring, which requires an earth connection. There is no symbol for a Class I product so if a rating plate has no symbol on it then it is usually Class I.
Class II - Double insulated wiring, therefore no need for an earth lead. Class II is indicated by double box.
Class III - These are appliances that are supplied at a low voltage (usually called Safety Extra Low Voltage) which must be less than 50V. These appliances are supplied with a transformer supply that is also marked.
Class 0 - Non-earthed metal appliance with two core cable. Sales of these items have been banned since 1975.