Getting Portable Appliance Testing/Electrical Equipment Testing right

Firstly, Portable Appliance Testing or Electrical Equipment Testing?
The fifth edition of the IET Code of Practice for In-Service Inspection and Testing of Electrical Equipment introduced updated terminology. The recommended term is now Electrical Equipment Testing (EET). The change from Portable Appliance Testing (PAT) was driven by the limitations of the word ‘portable’, which led some to mistakenly assume that only small, movable appliances required testing.

By adopting Electrical Equipment Testing, the industry emphasises that a wide range of devices requires assessment – from laptops, chargers and kettles to refrigerators, vending machines and industrial machinery. PAT testing remains the more familiar phrase, but regardless of whether it is referred to as PAT or EET, the process remains the same.

PAT/ EET
Every year a significant number of electrical accidents, many involving electrical appliances, are reported to the Health and Safety Executive (HSE) in the UK. In accordance with the Electricity at Work Regulations (1989), any electrical equipment that has the potential to cause injury must be maintained in a safe condition. Designed to help raise the standards of electrical safety in the workplace, testing ensures that electrical appliances and equipment are safe to use.

How often should the test be done?
The frequency of testing depends on the type of equipment, how it is used, and the environment in which it operates. High-risk workplaces such as construction sites will likely require more frequent inspections than lower-risk environments such as offices. The Health and Safety Executive (HSE) offer detailed guidance on setting appropriate intervals.

Who should perform the tests?
To help companies with their portable appliance testing strategy there are many commercially available EET/PAT training courses. These are invaluable to help provide the necessary theoretical and practical knowledge to undertake testing and inspecting different electrical appliances. While the fifth edition of the IET Code of Practice emphasises the need for risk assessment, partly to reduce unnecessary testing, it still requires that a competent person carry out Electrical Equipment Testing.

PAT/EET – 12 potential testing pitfalls
Even for the experienced competent person testing, there are 12 identified potential errors that need to be carefully avoided:

1. Not doing a visual inspection 
It may seem obvious, but before you measure the condition of an appliance, make sure that all its parts are there and in good condition. Any signs of damage, including any dents/scratches on the casing, should be reported. These can indicate that the appliance has been dropped or handled incorrectly at some point in its life. If the cable shows signs of wear or is not plugged in properly, it should be recorded as it could indicate that the appliance is unsafe.

2. Not doing the tests in the required order 
If on a Class 1 appliance you do the insulation test first, you don’t know if the conductive earth path is good (in Class 1 appliances most testers use the earth wire as the return signal path, which is why you don’t need to use a probe for the insulation test). If the earth path isn’t tested and proven good, you can’t rely on the insulation test.

3. Forgetting to switch the appliance on 
Think about the situation where the live wire is broken inside the appliance and touching the outer casing. When you do the insulation test, everything inside the appliance should be at 250V/500V. The tester detects (via a probe or the earth wire) any voltage escaping to the appliance housing. But if you haven’t switched it on the voltage can’t get through the live wire, nothing will escape and you could have an incorrect pass of a dangerous appliance. 

4. Touching the appliance 
The truth is most appliances pass the insulation test, so you get into the habit of holding drills etc. to make it easier to hold the probe in contact. Then one day the appliance insulation fails and results in a shock.

5. Only doing one earth bond test  
If an appliance has multiple, apparently isolated, outer parts with separate earthed paths, each one needs to be separately measured (some of the earliest testers had standard test sequences that only expected you to do one earth test).

6. Taking an average reading 
If you have multiple earth paths, don’t take the average reading – it’s the worst case that matters. 

7. Trying to do an earth bond test on a Class II appliance 
It will of course fail as Class II appliances have no earth. This is a very common problem and causes a large number of calls to technical help lines. 

8. Only doing one insulation test 
For the reason in point 5 above this is a common fault. At how many places on a power tool could the insulation break down? Obviously at the chuck, but what about the ventilation slots, the trigger, the assembly screws, the speed control?

9. Not checking the fuse is conducting (see point 3 above) 
You don’t have to do a separate fuse test – the function test will prove that the appliance is both on and the fuse is okay.

10. Failing to do a functional test (powering it up) 
Some entry level testers don’t have the ability to power up the appliance. If your tester doesn’t then plug the appliance into the wall socket (after testing) and make sure it works properly. Putting your initials on a PASS label for an appliance that doesn’t work or is obviously faulty could reflect poorly on you. 

11. Not testing at the correct voltage
It is very common for people to make the mistake of performing a 500V test on surge protection extension leads. These require a lower voltage 250V test, which is especially helpful when testing appliances with surge protected circuits, such as sensitive IT equipment at 250V. 

12. Not calculating the correct pass level 
Many appliances use longer power cables than those specified by the manufacturer. The current pass level for an appliance with a longer power cable is calculated differently than the pass level for an appliance with a shorter power cable. The current pass level for an appliance with a longer power cable can be determined by a calculation available in the PAT/EET code of practice.

Choosing the correct test equipment
Given the importance of PAT/EET testing and the wide variation in operating environments and equipment to be tested, it is extremely important to ensure the right equipment is selected to suit the application. For example, to enable minimal disruption some appliance testers are small handheld devices and therefore highly portable, enabling appliances to be tested on site rather than back at a central workshop. 

Conclusion
Neither PAT nor EET testing is mandated by law. However, employers are legally obligated to ensure electrical equipment is safe. Conducting regular inspections provides a recognised means of demonstrating compliance with the Electricity at Work Regulations 1989 and the Health and Safety at Work Act 1974.

Disclaimer: This article provides technical guidance and does not replace formal training, professional advice or regulatory requirements. PAT/EET testing and formal visual inspections must be conducted only by competent individuals with appropriate training and knowledge. Always consult the latest guidance from the HSE and IET and seek professional advice where necessary.

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