The aim of test and tagging is to determine if the appliance is electrically safe for personal use. The appliance undergoes a visual inspection for defects such as damage or missing components and a number of electrical tests to measure earth continuity, insulation resistance and polarity.
Because there is a document published on this topic by a reputable source, regulatory bodies that enforce State and Federal Occupational Health and Workplace Safety Acts and Electrical Safety Acts and Regulations within Australia and New Zealand, may list or encourage the use of this Standard as a minimum requirement.
Test and Tagging is sometimes referred to as PAT Testing.. This terminology was first used in the United Kingdom A Portable Appliance Test or PAT, is a process by which electrical appliances are routinely checked to see whether they are safe. The term PAT - Portable Appliance Tester - more accurately describes the actual test equipment used by technicians (not the appliance being tested) as it is generally hand held and/or portable.
In the United Kingdom, the law requires is that the appliances are safe (as far as is reasonably practicable). Guidance from the Institution of Electrical Engineers (IEE) and the Health and Safety Executive (HSE) suggest initial intervals for combined inspection and testing that range from three months (for construction equipment) to five years for inspection and never for testing (certain types of appliance in schools, hotels, offices and shops).
However the original United Kingdom term PAT (Portable Appliance Testing), is somewhat misleading as test and tagging can involve inspection and testing of fixed appliances, such as wall mounted air-conditioners that are not "hard wired" etc. Possibly a more accurate term for the whole process is In-service Inspection & Testing of Electrical Equipment.
For specific information about In-service Inspection & Testing of Electrical Equipment in the UK ,please refer to the Wikipedia page Portable Appliance Testing.
''“A Competent Person is one who the Responsible Person ensures has the necessary practical and theoretical skills, acquired through training, qualification, experience or a combination of these, to correctly undertake the tasks prescribed by this Standard.”
The Standard also notes a Competent Person is not required to be a registered or licensed electrical practitioner (ie electrician). However local Legislations, Industry Standards and/or Codes of Practice may have different requirements and therefore the better practice should be adopted.
Because there is a document published on inspection and testing of electrical equipment by a reputable source, regulatory bodies that enforce State and Federal Occupational Health and Workplace Safety Acts and Electrical Safety Acts and Regulations within Australia and New Zealand, may list or encourage the use of the Standard AS/NZS 3760:2003 In-service inspection and testing of electrical equipment as a minimum requirement.
The Standard also specifies procedures for Residual Current Devices / Safety Switches.
The Standard notes a number of exemptions including;
1.1.1 This Standard does not apply to electrical equipment (such as suspended light fittings), at a height of 2.5m or greater above the ground, floor or platform, where there is not a reasonable chance of a person touching the equipment and, at the same time, coming into contact with earth or any conducting medium which may be in electrical contact with earth or through which a circuit may be completed to earth.
1.1.2 This Standard does not apply to equipment which would need to be dismantled to perform the inspection and tests specified in this Standard.
NOTE If, for some reason outside the scope of this Standard, equipment must be dismantled to verify safety, this action must be performed by a technically qualified person.
1.1.3 Functional checks are not considered part of a safety evaluation and therefore not included in this Standard.
1.1.4 This Standard only applies to equipment in-service at a place of work or public place, or offered for hire.
NOTE For example, this Standard does not apply to demonstration stock in retail or wholesale outlets.
1.1.5 This Standard does not apply to fixed or stationary equipment connected to wiring that forms part of the electrical installation and falls within the scope of AS/NZS 3000.
1.1.6 This Standard does not apply to equipment whose nature is that of a medical device as defined in AS/NZS 3551.
Examples of common electrical appliances that would require testing;
An anomaly exists between the treatment of new equipment depending on whether it is entering into service in Australia or New Zealand.
Experience has shown that greater than 90% of defects are detectable by visual inspection. Typically this relates to damaged plugs/sockets, flexible supply lead, especially at flex point where lead enters plug/socket.
The tests an appliance is required to undergo will depend on the type of appliance, it's electrical Class and subject to a risk assessment by the technician. ie it may not be safe to perform a leakage current test which powers up the appliance, such as a grinder, if it can not be secured to a bench; an insulation resistance test may be a safe option.
The equipment shall have a measured resistance of the protective earth circuit, or the earthing conductor of an extension cord or appliance cord set, which does not exceed 1Ω.
Testing is performed using an ohmmeter or PAT tester;
The choice of which test(s) to use is at the operator's discretion as there is merit in each test for given situations, however the "routine test" is seldom used by competent persons as it simply replicates existing conditions for the (240V/10A) appliance and therefore the results are regarded as being of little test value.
Alternatively, measure insulation resistance values do not exceed 1MΩ for Class I and Class II appliances at 500 V d.c. or alternatively, to avoid the equipment apparently failing the test because the metal oxide varistors (MOVs), or electro-magnetic interference (EMI) suppression has triggered, for equipment containing voltage limiting devices such as MOVs, or EMI suppression, at 250 V d.c.
Leakage Current testing is performed using a PAT by applying a nominal voltage to the live conductors (active and neutral) of an appliance, and placing 0 volt reference on the earthed parts of a Class I appliance or the external metal parts of a Class II appliance;
Insulation Resistance testing is performed using an ohmmeter or portable appliance tester by applying a nominal voltage to the live conductors (active and neutral) of an appliance, and placing 0 volt reference on the earthed parts of a Class I appliance or the external metal parts of a Class II appliance;
A deficiency of the Insulation Resistance (500V/250V d.c) test is that the d.c voltage will not activate electromagnetic switches or internal relays etc that are common in many modern power tools, computers, TVs etc and therefore it can only test the appliance up to that point. Appliances with these components / design should be tested used the leakage current test.
In addition to this, many technicians also test;
Best Practice is to test the RCD under 1/2, 1X and 5X rated tripping current, each at both the 0 degree and 180 degree phases.
Where in-service inspection or testing identifies equipment which fails to comply with the inspection and/or testing criteria, the equipment shall be appropriately labeled to indicate that the equipment requires remedial action and warn against further use, and withdrawn from service. The choice of remedial action, disposal or other corrective action shall be determined by the owner or the person responsible for the safety of the site.
Most tags are applied approximately one hand span away from the plug end of the flexible supply cord to avoid handling damage and stress point loosening.
The tag can be applied to the body of an appliance if needed.
The Standard notes:
2.5.1 Where records of test and inspection are kept, the following should be recorded:
- (a) A register of all equipment;
- (b) A record of formal inspection and tests;
- (c) A repair register;
- (d) A record of all faulty equipment showing details of services or corrective actions.
NOTE 1 Electrical and/or occupational health and safety regulators may require documentation to be kept in some or all cases.
NOTE 2 Where organizations perform voluntary additional inspections and tests, records of such should be kept.
2.5.2 Where records are kept, they should be retained for seven years, or such period as required by the specific regulations.
2.5.3 Where a risk assessment has been performed in accordance with Clause 2.1.1, all documentation shall be retained for seven years or such period as may be required by the relevant Regulator.