Moveable objects and a commitment to safety

Health and safety plays a vital part in office life. In large buildings and businesses, its importance is magnified by the vast number of people who work within – or for – them. Due to the potentially fatal consequences of poorly maintained or damaged electrical equipment, keeping on top of this type of equipment’s functionality is a key priority for landlords, building owners and senior managers everywhere.

PAT testing, or portable appliance testing, is an important part of any health and safety policy. With figures from the Health and Safety Executive stating that 25 per cent of all reportable electrical accidents involve portable appliances, it is important that proper measures are in place to keep workers safe.

Employer responsibility
The Electricity at Work Regulations (1989) place a legal responsibility on employers, as well as employees and self-employed persons, to comply with the provisions of the regulations, and to take reasonable and practicable steps to ensure that no danger results from the use of portable equipment, this includes everything from kettles to photocopiers. This requires putting a systematic and regular programme of maintenance, inspection and testing in place.

The level of inspection and testing needed for portable equipment depends upon the risk of the appliance becoming faulty, which in turn depends upon the type of appliance, the nature of its use and the environment in which it is used.

So, what, exactly, does PAT testing involve, who should do it and how should it be managed on an ongoing basis?

Qualified professionals
Needless to say, the potentially dangerous nature of electrical equipment means that tests on portable appliances cannot be done by anyone other than a competent electrical professional. PAT testing is something that many ECA members are qualified to do as a matter of course; and are competent to do.

When an inspection is carried out, the equipment being inspected is checked for signs of visible damage or malfunction. A thorough review is made of the equipment itself, its connecting lead and plug. If the check reveals signs of damage, poor electrical standards, inadequate or temporary repairs to the equipment, lead or plug, it should be withdrawn from use and clearly labelled to indicate that it must not be used. This also applies to extension leads and associated plugs and sockets. Any equipment so labelled should be recorded on a log sheet.

A contractor qualified in PAT Testing will use the correct test equipment; this is of the utmost importance, as the safety of the equipment can only be ensured if the appropriate range of tests has been carried out. It is likely that the contractor will have instruments that undertake a series of tests on portable equipment, and where a large number of tests are to be carried out, the use of such instruments would seem the most sensible option considering the saving in time – and potential cost to an organisation – that could be made.

These tests should not be considered as definitive, however. Some items of equipment may, for one reason or another, require certain additional tests which must be assessed, by a competent person, at the time of testing. These include flash testing, ground bond testing and insulation resistance testing.

Flash testing
Flash testing evaluates whether the electric insulation section of an electric equipment or part is strong enough to cope with the working voltage. Flash testing is also called dielectric withstand test or hipot test.

Much equipment available today contains electronic components susceptible to damage when subjected to high voltages. Dielectric or flash testing should, therefore, only be carried out when the equipment has been extensively repaired and then only after the manufacturer has been consulted.

The earthing systems test performs a measurement of resistance to determine that the equipment remains safe in the event of internal live conductors touching the external case of the device under test. This test ensures that the earth or ground conductor can carry sufficient current to cause the supply protective fuse in the plug top, or protective device (e.g. circuit breaker), to blow before the case rises to a hazardous voltage.

Insulation resistance
The insulation resistance test involves applying a voltage – specifically a highly regulated, stabilised DC voltage – across a dielectric, measuring the amount of current flowing through that dielectric, and then calculating (using Ohm’s Law) a resistance measurement. Items of equipment that, from a visual check, appear to be acceptable but subsequently fail this test require further investigation.

It is important to remember that all electrical equipment deteriorates with age, so the use of a portable appliance tester, which has a pre-set value of insulation resistance acceptable for testing a new appliance, may be unduly onerous for an older item of equipment. A typical example of this is the table top type of cooker, which although not typically associated with office work, can be present in many employee kitchens so that they can bring in their own food for lunch etc. This can have a value of insulation resistance lower than the pre-set level and may therefore be deemed to have failed the test.

Frequency of testing
Organisations should determine the intervals between both inspection and testing by assessing the risk, i.e. the likelihood of danger arising. This will vary with the type of equipment, usage, as well as the nature of the environment in which it is used. Also, the age of the equipment and previous test results need to be considered. The frequency of inspection can be determined by experience and will generally be more frequent than testing.

More demanding conditions will mean that more frequent inspection and testing is needed, while less onerous conditions – and good inspection and test results – can lead to a reduced frequency.

IT equipment
Many organisations do not realise that PAT testing should also be undertaken on IT equipment. However, many items of equipment typically found in the modern office environment contain electronic components that may be damaged if connected to a portable appliance tester, so great care must be exercised when dealing with this equipment; another reason for calling in a professional with PAT Testing qualifications.

Your electrical contractor will know that most IT equipment is sensitive to changes in voltage levels applied to it, and that such equipment contains circuitry to minimise the effects of these fluctuations. This circuitry may lead to erroneous readings when the equipment is tested, indicating that the equipment has failed due to too low a reading, e.g. insulation resistance. If experienced, the tester will be aware of this possibility and may have to substitute the earth leakage test for an insulation resistance test if this situation arises.

After the test
After completion of the tests, the organisation’s responsible person – in charge of the testing – should make sure that the contractor has individually marked each item of equipment tested indicating whether it passed or failed the tests, the date of the test, and the date a re-test is due.

It is also recommended that the contractor records details of the tests and results onto a log sheet kept by the organisation. A check should be made to ensure that the details entered on the test label, fixed to the equipment, tally with those entered on the log sheet.

It is of paramount importance that a record of maintenance, including test results, is maintained throughout the life of each item of equipment. The provision of these records will demonstrate that testing has been carried out to an adequate standard, and any difference between subsequent tests can be noted. Should these tests show deterioration in any part of the equipment, remedial action is necessary to ensure that danger does not arise.

It is worth noting that some of the more advanced portable appliance testers can store the information in their own memory. This information can be transferred into the organisation’s database for record keeping purposes and analysis.

Finally, if the equipment tested fails any of the inspection or tests, the organisation must immediately withdraw it from service until the fault has been rectified. Further investigation of the reason for failure will normally be required. After repair of the fault, the equipment should be retested before it is returned to service.

It may seem complex, but with help from competent electrical professionals, PAT Testing is a painless procedure for organisations, but one that is vital to ensure the running of a healthy and safe office.

About ECA
The ECA represents the interests of 3,000 member companies involved in electrical installation work. Collectively, the member companies have an annual turnover of more than £5 billion, employ over 30,000 operatives and support 8,000 apprentices in craft training. The role of the ECA is to provide a focus for the electrical industry in terms of safety, training, qualification, technological development and industry performance.

About the author
Giuliano Digilio joined the ECA in 1992 from Emcor Drake and Skull, where he was engineering manager working in design management. He benefits from extensive experience in the electrical engineering building services industry, covering a broad range of areas including technical design, construction, project management and the commercial aspects of various electrotechnical installations and systems.

Giuliano sits on numerous technical Committees for both ECA and industry. He is also Chairman of the AIE (European Contractors’ Association) Home & Building Electronic Systems Task Force, and a member of their Policy Co-ordination Committee. In addition, he is a Fellow of the IET (Institution of Engineering and Technology), an Associate Member of CIBSE (Chartered Institution of Building Services Engineers) and also belongs to the Light & Lighting Society.

For more information:
Web: www.eca.co.uk