What is pat testing? how does it work?

UK Home Improvement

What Is PAT Testing? How Does It Work?

These days, electrical appliances often fill commercial and residential buildings. Smart televisions, coffee makers, toasters, microwave ovens, printers, and desk computers allow us to perform our tasks and live comfortably at home or work. 

These appliances and equipment must be checked regularly to avoid fire and electrocution hazards. And that’s where portable appliance testing, or PAT, comes in.  

If you’re reading this term for the first time, you’re on the right page. This article discusses the basics of PAT, primarily what it is and how it works. 

What Is PAT Testing?  

As previously mentioned, PAT stands for portable appliance testing. Despite the redundancy, people use the term, PAT Testing, to define the routine test and inspection activities performed by licensed electricians. These often include visual inspections and specialised testing tools for a thorough check. 

The fundamental purpose of PAT testing is to ensure that devices are safe to use and prevent electrical accidents in homes, offices, and other settings. As such, it should only be done by a professional with PAT testing certification

Similarly, every appliance that underwent the testing must be marked, and the results must be recorded for further reference. The record, commonly known as a PAT test certificate, can validate compliance with specific fire safety laws in the UK, especially for commercial establishments. 

As an aside, the UK’s Fire and Rescue Services report showed they attended to over 577,053 incidents as of March 2022. The office recorded 272 fire-related fatalities during the same period. 

Which Appliances Should Be Tested? 

Contrary to the term, this safety procedure doesn’t only involve portable appliances but other pieces of electrical equipment as well. While there is no specific definition of a ‘portable appliance’ in the law, common sense dictates that it covers any electrical appliance that needs to be plugged into an outlet to work.  

Specifically, there are seven appliance categories often considered for basic visual examination or in-depth PAT testing: 

  1. Fixed appliances, such as heating, ventilation and air conditioning system, can’t be moved. Visual inspections should be done occasionally; an in-depth PAT may not be necessary. 
  2. Stationary appliances are often bulky pieces that can be moved around but are usually located in the same area, like fridges and washing machines. Visual inspection can be done in high-risk environments; a PAT test is required. 
  3. IT appliances encompass business equipment like printers and computers. They have the same testing conditions as above.
  4. Moveable appliances are electrical devices lighter than 18 kilograms and can be moved easily. They must be visually inspected and PAT tested.   
  5. Portable appliances are tools that need to be moved while plugged into a power source. Because of higher risks, they need both procedures. 
  6. Cables and chargers likewise need to be visually inspected and PAT tested.
  7. Handheld appliances like electric drills and hair dryers pose higher hazards and must be inspected. 

What Are The Steps Involved In PAT Testing? 

Qualified professionals should do PAT testing, which involves the following procedures: 

Visual Inspection 

A qualified electrician performs this procedure before any PAT testing. This spot-checking procedure should be done only after unplugging the electrical device. 

The tester will check the following parts for physical signs of damage and issues: 

  1. Plug—They must show no signs of disfigurement and be connected securely to the terminals. 
  2. Cable or wire—They must not have cuts and must be securely wrapped in an insulator. An exposed wire is an electrical hazard.  
  3. Electrical unit—The machine in question should not show signs of degradation like burns and cracks. 
  4. Mains socket—Cracks and loose fittings can lead to malfunctioning. A fixed wire test should follow a visual examination of this section. 
  5. Residual Current Device (RCD)—The unit must show no signs of physical damage. An electrician will check the RCD’s operating current and test buttons during PAT testing.  
  6. Environment—The PAT tester will check the surrounding areas for risks that can cause fire, electrocution, and tripping. 

After this physical inspection, it’s time for a more thorough examination.  

Manual Testing 

An electrician will use certain pieces of equipment to conduct in-depth inspections. It’s crucial to hire an experienced professional to perform these tests safely. For this, they must have the right equipment and proficiency in properly using the testing devices. More importantly, they must know what to look for and how to interpret the test results. 

Common PAT testing procedures include: 

  1. Earth continuity
  2. Lead polarity
  3. Insulation resistance

After examining the appliance, the PAT tester will attach a pass or fail sticker. Machines with failed ratings must be removed, replaced or repaired. Refurbished devices must undergo another PAT test to ensure they’re safe. 


PAT testing is one of the best ways to determine the safety and soundness of electrical equipment. Homeowners must have time to test their appliances to protect themselves from damaging yet preventable accidents. Owners of commercial and residential spaces are legally required to have appliances or electrical equipment. Landlords should be extra vigilant with PAT testing before renting out units. 


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