Changes to the IEE PAT code explained

Jim Wallace of Seaward highlights the main changes in the new IEE Code of Practice for portable appliance testing.

The IEE Code of Practice for In-Service Inspection and Testing of Electrical Equipment provides a timely reminder to all those with a responsibility under the Electricity At Work Regulations 1989 for maintaining the safety of electronic and electrical safety of appliances used in the workplace.

By providing comprehensive guidance on periodic inspection and testing it ensures that organisations, administrators and those carrying out the testing fully understand the requirements of the EAWR 1989 and can demonstrate compliance with it.

Recently the IEE has reviewed the Code of Practice and is in the process of publishing its 3rd edition to take into account technology advances and the implications of other market changes in relation to in-service electrical safety testing.

By expanding the Code of Practice by over 50 pages, the revised publication provides much clearer guidance on all aspects of portable appliance testing with the addition of a number of useful illustrations.

As an example, whereas the previous document provided detailed advice on checking mains plugs and cables, the revised version is supplemented by the inclusion of multiple illustrations showing typical faults that might be encountered.

Similar clarification and added details are provided for all aspects of the inspection and test process.

In addition, the new code has brought some much needed clarification on the scope of equipment to be tested for electrical safety.

For example, in the past certain types of electrical equipment, such as hand dryers for example, may have been regarded as an appliance by anyone testing the electrical installation, or as a fixed installation by anyone carrying out in-service testing.

As a result, such items of electrical equipment may have remained untested.

To overcome such confusion the new IEE Code makes it clear that appliances which are connected to the electrical supply by a flex should be tested, even if they are permanently installed.

However, as well as the inclusion of many more informative diagrams, some of the main changes in the updated IEE Code concern new requirements in relation to RCDs.

In particular the revised version stipulates that when an extension lead or multiway adapter is fitted with an RCD, the operation of the RCD should be checked using an RCD test instrument to determine that the trip time is within specified limits.

For those responsible for carrying out portable appliance testing this may require some changes to be made to the type of test instruments used.

However, Seaward has anticipated these changes, and many of the company's testers are now equipped with an RCD trip time test.

The other area of significant change in the latest IEE Code of Practice is in the area of insulation testing.

Testing insulation resistance at 500V DC can be problematic when the equipment under test is fitted with transient suppressors or mains filtering and until now the only alternative was to perform a protective conductor/touch current measurement.

The revised Code of Practice introduces two new test methods which can be used as an alternative to the 500V insulation test.

The first method is to reduce the insulation test voltage to 250V DC, and the second is to perform an alternative/substitute leakage measurement.

Alternative or substitute leakage is measured using a technique similar to that used when measuring insulation resistance.

A test voltage is applied between both live conductors (phase and neutral) and the protective conductor (earth) during a Class I test or a test probe connected to the equipment enclosure during a Class II test.

The resultant current is measured and then scaled to indicate the current that would flow at the nominal supply voltage.

The test voltage is 50Hz AC and normally in the range of 40 to 250V.

The test voltage is current limited and so there is no hazard to the test operative.

As the test voltage has the same nominal frequency as the mains supply the leakage paths are similar to those found when the equipment is in operation.

Similarly, because the test voltage is not greater than the nominal supply voltage of the equipment under test, measurements are not affected by transient suppressors, MOVs or other voltage limiting devices.

On a more general note, it has always been recognised that the PAT equipment used for testing should be calibrated annually or in accordance with manufacturers' instructions.

A calibration certificate is issued which states that the test instrument is within specification at the time the calibration is performed.

The certificate does not guarantee the performance of the test equipment at any time after that and the revised IEE Code of Practice now recommends that test equipment is checked at regular intervals using a verification device such as a PAT Checkbox.

In addition, a record of the performance checks taken should also be kept and the revised document includes a specimen test instrument record form.

Finally, the latest edition of the IEE Code also provides some clarification on the competency of those required to carry out the testing.

The EAWR already require that testing should be carried by a competent person and specifically, the IEE Code advises that this person should possess sufficient technical knowledge or experience to be capable of ensuring that injury is prevented.

The new code continues with further explanation on what that technical knowledge or experience may comprise, including such factors as having an adequate knowledge of electricity, an adequate understanding and practical experience of the system to be worked on and an understanding of the hazards that may arise and the precautions.

A free PAT testing guide is available now from Seaward.

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