Lead Tests:

Most testers will incorporate some test designed to check extension or IEC leads. These tests will include most of the above as well as continuity and polarity checks. In the case of two core leads, test them as a class 2 appliance. Lead lengths should not exceed the following:

1.25mm leads 12 metres

1.5mm leads 15 metres

2.5mm leads 25 metres

ANY lead exceeding those those lengths should be used in conjunction with an RCD rated at 30mA Very long leads will probably fail the 0.1ohm limit for the earth test due to the resistance of the lead so some simple arithmetic will be required.

The photo below shows how a very short IEC lead can be used to cause the test set to "SEE" an extension lead as an IEC lead. If the length of the extension lead is known, then the table below the photo can be used to calculate the expected resistance of the lead under test. If necessary this technique can be used in the absence of one of the special adapters often sold specifically for testing extension leads.

CAUTION: Throughout the testing procedure it is important not to touch the appliance. High voltages are used and care must be exercised. There does not appear to be any statutory definition of a competent person. However for practical purposes a person may be considered to be competent if that person is

“in possession of the necessary theoretical knowledge and practical experience considered appropriate for that person to assess the safety criteria for a particular situation”.

This manual has attempted, whilst avoiding all the "bells and whistles" to provide the information required to carry out the formal visual inspection of electrical appliances so as to assess their safety. As has been stated earlier internal faults may not be evident by a purely visual check. Therefore if there is any reason to suspect the condition of an appliance, or if any appliance has been the subject of a repair, then that appliance should be made the subject of a full electronic test carried out by a suitably trained person using a purpose built Portable Appliance Tester.

There is a wide range of these instruments available from most electrical wholesalers. Although there are some very sophisticated (and expensive) models available, simpler versions are usually perfectly adequate, come with complete instructions and require no interpretation of results sometimes required from the professional range. Most have their own set of instructions regarding how to download test results to a PC. Therefore no attempt has been made to include this aspect of the work, as it would not be practical to adequately cover all types of test instrument and software combination out there.

IMPORTANT: Before checking cables , plugs etc. always check that equipment is unplugged. Also be aware that even when unplugged voltage may still remain, particularly when dealing with some types of equipment. (eg UPS devices or appliances containing capacitors)