The IEE (Institution of Electrical Engineers) and the IIE (Institution of Incorporated Engineers) joined together in 2006 to form the IET (Institution of Engineering and Technology).

All titles published previously by the IEE and IIE are now published by the IET (where applicable)

This is the 5th edition of the IET's Code of Practice for In-service Inspection and Testing of Electrical Equipment (PAT Testing).

This Code of Practice provides advice on in-service inspection and testing to determine whether electrical equipment is fit for continued service. It reinforces the need of the duty-holder to conduct inspection and testing of equipment by considering the risks the equipment is exposed to, the environment it is used in, along with the skill level of the user. This 5th Edition reinforces the necessity to establish and conduct appropriate safety checks, taking into account current working practices and legal requirements.

Among some of the changes reflected in this edition are: the need for electrical equipment maintenance; changes to acceptable test result limits and the hierarchy of tests; suggestions for how to approach testing frequency and intervals; reaffirmation of the demarcation between equipment connected to a fixed electrical installation and the installation itself; greater emphasis and guidance regarding user-checks; and advice on the types of test available to duty-holders.

The core purpose of this Code of Practice is to help achieve high standards of electrical safety.