PAT Testing Frequency Guide

IET Code of Practice 5th Edition – How Often Should You PAT Test?

One of the most common questions electricians and duty holders ask is how often should PAT testing be carried out? The answer changed significantly in November 2020 when the IET published the 5th Edition of the Code of Practice for In-Service Inspection and Testing of Electrical Equipment. This guide explains what changed, what the current guidance says, and how to determine the right PAT testing frequency for your clients.

The biggest change in the 5th Edition was the complete removal of the fixed frequency table (Table 7.1 in the 4th Edition). This table had been the go-to reference for PAT testing intervals since the first edition was published in 1994. It listed specific retest periods for different types of equipment in different environments, and most electricians used it as gospel.

The IET removed it because too many people were treating it as a rigid legal requirement rather than guidance. The table was always intended as a starting point, but in practice it became a substitute for proper risk assessment. The 5th Edition now places risk assessment at the centre of the process for determining how often equipment should be inspected and tested.

Under the 5th Edition, the duty holder (the person responsible for the equipment, typically the employer or landlord) must carry out a risk assessment to determine suitable inspection and testing intervals. The risk assessment should consider:

The 5th Edition includes sample risk assessments in its appendices to help duty holders and PAT testers work through this process. The intent is clear: rather than blindly following a table, you should think about the actual risk and set intervals accordingly.

Although the fixed frequency table was removed from the 5th Edition, the intervals from the 4th Edition remain widely used across the industry as practical benchmarks. The HSE also publishes guidance with suggested initial intervals in their document Maintaining Portable Electrical Equipment. These intervals are a sensible starting point before adjusting based on your risk assessment.

Beyond the frequency changes, the 5th Edition introduced several other updates that affect how PAT testing is carried out:

Removal of equipment type classifications – The terms portable, movable, hand-held, stationary, and fixed have been removed. The 5th Edition applies to all electrical equipment that is not covered by another inspection regime (such as an EICR for the fixed installation). This closes the gap where items like water coolers, hand dryers, and vending machines were often missed because they did not fit neatly into the old categories.

Changed test limits – The insulation resistance pass threshold has been updated. The 4th Edition used a 1 MΩ minimum for Class I equipment. The 5th Edition retains this but provides additional guidance on interpreting borderline results and trending values over time.

Counterfeit equipment guidance – A new appendix (Appendix 13) addresses the growing problem of counterfeit and substandard electrical equipment, particularly cheap chargers, adaptors, and extension leads imported from overseas. Spotting these during visual inspection is now an explicit part of the process.

Hierarchy of testing – The 5th Edition reinforces that visual inspection should always come first, and that many faults can be identified without electrical testing. Electrical tests should only be carried out where the visual inspection does not provide sufficient confidence that the equipment is safe.

Updated City & Guilds qualification – The PAT testing qualification was updated to City & Guilds 2377-77, replacing the 2377-22. The exam is based on the 5th Edition and is open book, so you will need a copy of the current Code of Practice.

The actual tests performed depend on the class of equipment. The IET Code of Practice sets out the following hierarchy:

Visual inspection – Checking the plug, cable, and equipment casing for damage, correct fuse rating, signs of overheating, and any modifications. This is the most important part of PAT testing and catches the majority of faults.

Earth continuity test (Class I only) – Verifies that the earth connection from the plug pin through the cable to the equipment casing is intact and has sufficiently low resistance. The pass limit is (0.1 + R) ohms, where R is the resistance of the supply cable.

Insulation resistance test – Checks that the insulation between the live/neutral conductors and earth (Class I) or between the live/neutral conductors and accessible parts (Class II) is adequate. The minimum acceptable value is 1 MΩ for both Class I and Class II equipment.

Functional check – Confirming the equipment operates correctly after the electrical tests. This includes checking that switches, thermostats, and safety interlocks function as intended.

Understanding the difference between Class I and Class II equipment is essential for determining which tests to carry out:

Testing everything annually regardless – The single most common mistake. Many PAT testers default to annual testing for all equipment because it is simple to manage and generates repeat business. But the IET Code of Practice and the HSE both state that the frequency should be based on risk. Office IT equipment that sits on a desk and never moves does not need annual testing. Construction site tools do.

Not doing user checks between formal tests – A formal PAT test is only a snapshot. Equipment can develop faults at any time. The Code of Practice recommends regular user checks, which are simple visual inspections carried out by the person using the equipment. These do not require any test instruments and can be done by anyone with basic training.

Ignoring the visual inspection – Some PAT testers rush through the visual inspection to get to the electrical tests. The visual inspection catches the majority of faults. A damaged cable, a cracked plug, or a missing earth pin are all serious faults that require no test instrument to detect.

Testing brand new equipment – New equipment that carries a CE or UKCA mark has already been tested to product safety standards. The 5th Edition states that formal testing of new equipment is generally unnecessary provided it has been visually inspected and there is no reason to believe it is faulty or counterfeit.

Not recording results properly – The value of PAT testing is lost if results are not recorded and maintained. A proper record allows you to track trends, justify your chosen test intervals, and demonstrate compliance to insurers and enforcement bodies. Using a digital PAT testing system rather than paper forms makes this significantly easier.

Is PAT testing a legal requirement?

Not in itself. The Electricity at Work Regulations 1989 require employers to maintain electrical equipment in a safe condition. The Health and Safety at Work Act 1974 places a general duty on employers to ensure the safety of their employees. PAT testing is the recognised and accepted method of meeting these obligations, but the law does not mention PAT testing by name or mandate specific intervals.

Do I need to be a qualified electrician to PAT test?

No. The Electricity at Work Regulations require that testing is carried out by a competent person, but they do not define a specific qualification. In practice, holding the City & Guilds 2377-77 qualification demonstrates competence and is expected by most clients and insurers. A qualified electrician is more than competent to carry out PAT testing but does not need a separate qualification to do so.

Do I need the IET Code of Practice book?

If you are taking the City & Guilds 2377-77 exam, yes – the exam is open book and based on the 5th Edition. For practising PAT testers, it is strongly recommended as the authoritative reference for how to carry out in-service inspection and testing properly. It is available from the IET shop and most electrical wholesalers.

Can I extend the testing interval if equipment consistently passes?

Yes. The 5th Edition explicitly supports this approach. If equipment in a given environment consistently passes with no faults over multiple test cycles, it is reasonable to extend the interval. Document your reasoning as part of the risk assessment so you can justify the decision if questioned.

What about working from home equipment?

If an employer provides electrical equipment for an employee to use at home, the employer retains responsibility for ensuring it is safe. The 5th Edition acknowledges remote and hybrid working and the equipment provided for it falls within the scope of the Code. In practice, many employers issue guidance for home workers to carry out their own user checks and arrange formal testing when the equipment is brought into the office or collected.