PAT Testing Frequency: How Often by Premises Type

PAT testing (Portable Appliance Testing) is the in-service inspection and testing of electrical equipment to confirm it is safe for continued use. The testing frequency is not fixed by law — instead, the IET Code of Practice for In-Service Inspection and Testing of Electrical Equipment (5th Edition) provides recommended intervals based on the type of premises and the type of equipment. PAT testing is one of the 16 certificate types that UK electricians commonly produce.

The Code of Practice is published by the Institution of Engineering and Technology (IET) and is the recognised industry standard for PAT testing in the UK. It is referenced by the Health and Safety Executive (HSE) as the standard that, if followed, demonstrates compliance with the maintenance requirements of the Electricity at Work Regulations 1989.

Understanding the recommended intervals is essential for electricians who offer PAT testing services — it allows you to advise clients correctly, set up appropriate testing schedules, and price PAT testing contracts accurately. It is also important for building managers, facilities teams, and business owners who need to ensure their portable equipment maintenance programme meets legal requirements.

The following table summarises the IET Code of Practice recommended intervals for user checks, visual inspections, and formal combined inspection and testing. These intervals are starting points — the risk-based approach may require shorter intervals in some situations.

The IET Code of Practice emphasises that the recommended intervals are starting points, not absolute rules. The duty holder should adopt a risk-based approach that considers the specific circumstances of their equipment and environment.

Factors that may justify more frequent testing include: equipment used in harsh or wet environments, equipment that is frequently moved or transported, equipment used by multiple people (such as shared tools or hire equipment), equipment with a history of damage or faults, equipment that is critical to safety (such as medical devices or fire safety systems), and cable-connected equipment that is subject to mechanical stress.

Conversely, factors that may justify less frequent testing include: equipment that is permanently installed and never moved, equipment in a clean, dry, low-risk environment, equipment that has consistently passed previous tests with no issues, and double-insulated (Class II) equipment that does not rely on an earth connection.

The risk-based approach means that a blanket "annual PAT testing" policy may not be appropriate for all equipment in all environments. Some equipment may need testing every 3 months; other equipment may safely go 48 months between tests. The key is to assess the risk for each category of equipment in each environment and set the testing interval accordingly. For fixed electrical installations, a separate EICR (periodic inspection) is required — PAT testing covers only portable and movable equipment.

The testing requirements differ between Class I and Class II equipment because of the fundamentally different ways they provide protection against electric shock.

In practice, Class I equipment should generally be tested more frequently than Class II equipment of the same type used in the same environment. This is because the earth connection can deteriorate over time (particularly if the cable or plug is damaged), and the loss of the earth connection removes the primary fault protection mechanism.

New equipment from a reputable manufacturer is expected to be safe for use without formal PAT testing. The manufacturer is responsible for ensuring that the equipment meets the relevant product safety standards before it is placed on the market. However, the IET Code of Practice recommends that new equipment receives a visual inspection before being put into service.

This visual inspection checks for damage that may have occurred during transport or storage — a cracked plug, a damaged cable, a loose fitting, or visible signs of manufacturing defects. If the visual inspection reveals no issues, the equipment can be put into service and included in the normal PAT testing schedule at the intervals appropriate for the premises type.

Some organisations choose to formally test all new equipment before first use to establish baseline readings. This is particularly useful for Class I equipment, where recording the initial earth continuity and insulation resistance values provides a benchmark for future tests. If a subsequent test shows a significant change from the baseline, it may indicate deterioration even if the values are still within the pass limits.

Equipment that has been repaired must be formally inspected and tested before being returned to service. This applies regardless of the nature of the repair — whether it is a plug change, a cable replacement, a component replacement, or a more significant repair.

The post-repair test confirms that the repair has been carried out correctly and that the equipment is safe for use. For Class I equipment, this includes earth continuity and insulation resistance tests. For Class II equipment, it includes an insulation resistance test. If the equipment fails the post-repair test, it must not be returned to service until the issue is resolved.

The person carrying out the repair must be competent to do so, and the repair and subsequent test results should be recorded in the PAT testing register — see certificate retention periods for how long to keep PAT records. The next test date should be set according to the normal testing schedule for the premises and equipment type.

The IET Code of Practice distinguishes between three levels of inspection:

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For electricians who offer PAT testing as a service, managing testing schedules across multiple clients and premises is one of the biggest operational challenges. Each client has different equipment, different premises types, different risk profiles, and therefore different testing intervals.

The most effective approach is to use a digital certificate system that tracks equipment by client and premises, records test results and next test dates, and generates reminders when re-tests are due. This allows you to proactively contact clients when their PAT testing is due, rather than waiting for them to remember — which they often do not.

A well-managed PAT testing schedule also forms the basis for recurring revenue. A school with 200 items needs annual testing. A hotel with 500 items needs annual testing. A construction company with 100 tools needs quarterly testing. These are predictable, repeating contracts that provide steady income throughout the year.

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When quoting for PAT testing contracts, consider the following factors: the number of items to be tested, the premises type (which determines the testing interval), whether the items are Class I or Class II, the geographical location and travel time, whether remedial work (such as plug changes or cable repairs) is included in the quote or billed separately, and whether the client requires labelling, a register, and a certificate. Electricians registered with NICEIC or NAPIT can use PAT testing as an additional revenue stream alongside their core installation and inspection work.