PAT testing stands for Portable Appliance Testing. It is a process of inspecting and testing electrical appliances to ensure they are safe to use. This type of testing is typically carried out in the United Kingdom, but similar processes exist in other countries as well.
PAT testing involves a visual inspection of the appliance to check for any damage, followed by a series of electrical tests to verify the electrical safety of the appliance. The tests may include checks for earth continuity, insulation resistance, and leakage current.
PAT testing is important because faulty or damaged appliances can cause electric shocks, fires, or other hazards. By regularly testing electrical appliances, you can identify and fix any problems before they become serious safety risks.
Earth Continuity Test
Earth continuity is a critical aspect of Portable Appliance Testing (PAT). It refers to the electrical connection between the metal casing of an appliance and the earth terminal of the power supply.
In PAT testing, a test is conducted to check if the earth continuity is present and functional. This test is typically done using a device called a PAT tester, which sends a small electrical current through the metal casing of the appliance and checks if it returns through the earth wire. The resistance of this return path is measured, and if it is too high, it indicates a problem with the earth continuity.
A good earth connection is important because it provides a safe route for electrical current to flow to earth if a fault occurs, such as a live wire touching the metal casing of an appliance. Without a good earth connection, the metal casing of the appliance could become live, which could result in electric shock or fire.
Overall, earth continuity testing is an important part of PAT testing because it helps ensure that electrical appliances are safe to use and do not pose a risk of electric shock or fire.
Insulation Resistance Test
Insulation resistance is another important aspect of Portable Appliance Testing (PAT). It refers to the ability of an electrical appliance to prevent current from flowing through its insulation material to the earth or other conductive surfaces.
In PAT testing, insulation resistance testing is conducted to check if the insulation of an appliance is in good condition. This test is typically done using a device called a PAT tester, which applies a high voltage to the appliance’s insulation and measures the resistance of the insulation material.
The measured resistance should be above a certain minimum value, which is usually specified by the manufacturer or regulatory standards. If the measured insulation resistance is too low, it indicates a problem with the insulation, which could lead to electric shock or fire.
Insulation resistance testing is particularly important for appliances that are exposed to harsh environments, such as moisture or high temperatures, which can degrade the insulation material over time. It is also important for appliances with movable or flexible parts, such as power cords or cables, which are prone to wear and tear and can cause insulation damage.
Overall, insulation resistance testing is an essential part of PAT testing because it helps ensure that electrical appliances are safe to use and do not pose a risk of electric shock or fire due to faulty insulation.
Leakage Current Test
Leakage current is another important aspect of Portable Appliance Testing (PAT). It refers to the small amount of electrical current that flows from an appliance through its insulation to the earth or other conductive surfaces.
In PAT testing, leakage current testing is conducted to check if the appliance is safe to use and does not pose a risk of electric shock or fire. This test is typically done using a device called a PAT tester, which applies a test voltage to the appliance and measures the current that flows through its insulation to the earth or other conductive surfaces.
The measured leakage current should be below a certain maximum value, which is usually specified by the manufacturer or regulatory standards. If the measured leakage current is too high, it indicates a problem with the insulation, which could lead to electric shock or fire.
Leakage current testing is particularly important for appliances that are used in wet or damp environments, such as bathrooms or kitchens, as well as appliances with metal casings or exposed conductive parts that could come into contact with people.
Overall, leakage current testing is an essential part of PAT testing because it helps ensure that electrical appliances are safe to use and do not pose a risk of electric shock or fire due to faulty insulation and leakage current.
Is PAT Testing Law?
The Electricity at Work Regulations 1989 require that any electrical equipment that has the potential to cause injury is maintained in a safe condition. However, the Regulations do not specify what needs to be done, by whom or how frequently (ie they don’t make inspection or testing of electrical appliances a legal requirement, nor do they make it a legal requirement to undertake this annually).
Do I need to be an Electrician?
The person doing testing work needs to competent to do it. In many low-risk environments, a sensible (competent) member of staff can undertake visual inspections if they have enough knowledge and training. However, when undertaking combined inspection and testing, a greater level of knowledge and experience is needed, and the person will need:
- the right equipment to do the tests
- the ability to use this test equipment properly
- the ability to properly understand the test results
Is PAT Testing compulsory?
No. The law simply requires an employer to ensure that their electrical equipment is maintained in order to prevent danger. It does not say how this should be done or how often. Employers should take a risk-based approach, considering the type of equipment and what it is being used for. If it is used regularly and moved a lot eg a floor cleaner or a kettle, testing (along with visual checks) can be an important part of an effective maintenance regime giving employers confidence that they are doing what is necessary to help them meet their legal duties. HSE provides guidance on how to maintain equipment including the use of PAT.
