AS/NZ 3760 : 2003
The AS/NZ 3760 : 2003 is document written by Australia and New Zealand Standards that specifies the procedures and criteria for the in-service safety inspection and testing of electrical equipment which is designed for connection by a flexible cord. It also applies to cord extension sets, portable outlet devices, portable residual current devices.
This standard outlines the testing procedures for Class I (earthed) appliances and Class II (double insulated) appliances
Tests that should be performed are as follows:
1. Visual Inspection
The most important test is a Visual Inspection of the device, especially its leads. Cords should be firmly anchored in plugs, connections made solidly with no frayed ends. Copper terminals should be clean and not pitted.
There should be no sign of heat or melting of plugs. Leads should be visually inspected for their entire length to ensure that there are no cuts, cracks or breaks. This test alone represents 80% of the testing process.
A Polarity test is done on leads, power boards, etc, and is functional check that Active, Neutral and especially Earth are not incorrectly wired.
3. Insulation Resistance
This test is important on appliances which come in contact with water such as pumps, cleaning and cooking appliances etc, but must be performed on all items. This will reveal if there are any hairline cracks or cuts in the lead which will result in a low insulation resistance. The resistance is measured at 500V or 250V with appliances with MOVs (surge protectors) between active and neutral to earth.
No less than 1M ohm resistance should be measured form live parts to exposed metal.
4. Earth Resistance
This test will ensure that a class I appliance has a low resistance earth connected to any external metal
No greater than 1 ohm resistance should be measured from the earthing conductor to external metal.
5. Current Leakage
This test will test if any current is leaking out of the circuit. Kirchhoff's current laws states that the current input is equal to the current on the out put. in appliance terms the current flowing through the active pin should equal to current flowing through the neutral pin. if it does not that the current is leaking some where else. This is normal due to a fault in the appliance.
This test must be performed on all appliances that must be energized to be switched on. That means that a leakage test must be performed if there is any electronic switching in the appliance (there is no way to know if there is electronic switching in a device so it is recommended that a leaking test is performed when possible.)
No more that 5mA in class I or 1mA in class II appliances should be measured
6. The Tag Itself
A tag will be applied to the plug end of the appliance lead. It will clearly state the date of the test or date it is due to be retested, and who tested it or company that tested, at a minimum. But is recommend that all these things are recorded.
Even though there is no mention to record keeping in the standard A complete test record should be completed. Including:
The frequency of inspection is outlined in Section 2.1 of the standard. There are recommendations in Table 4 but retest periods can be varied subject to a risk assessment. This table sets out testing and inspection intervals for various types of equipment from 3 months (for equipment that is high use, high risk, or hire equipment) to up to 5 years (for equipment that is not open to abuse, flexing of cords, etc).