For Australia/New Zealand, check that your power system complies with AS/NZS 3260:1993, Appendix 3, DC Component from AC Equipment
basically this limits the dc component of the input current to 5 mA or less, with the goal to reduce corrosion at earthing electrodes. Many power supplies use small internal overhead power supplies and it has been very common to operate these 1/2 wave rectifier mode. These will fail the 5 mA limit. Very many power supply manufacturers are unaware of this unique requirement. The test itself can be a bear since the permitted value is so small relative to the mains ac currents. However---"If it is evident from the design of the equipment that there will be no dc component, e.g. equipment provided with full-wave mains power supply or a mains isolating transformer, this test is not conducted". Bob
