PAT Testing: When It Is Required, How Often, and What to Record

What the Law Actually Says About PAT Testing

There is no UK law that says you must PAT test your equipment every year. That surprises a lot of people, but it is true. What the law does say — specifically the Electricity at Work Regulations 1989 and the Provision and Use of Work Equipment Regulations 1998 (PUWER) — is that all electrical equipment used at work must be maintained in a safe condition. How you achieve that is largely up to you.

The Health and Safety Executive (HSE) is explicit on this point: fixed-interval annual testing is not a legal requirement and in many cases is unnecessarily frequent. What matters is that you have a documented, risk-based approach to maintaining portable appliances. PAT testing is one tool for doing that — and in most workplaces it is the sensible choice — but the frequency and scope should reflect the actual risk environment.

The Electricity at Work Regulations place a duty on the employer (or self-employed person) to ensure that no electrical equipment is used where its strength and capability may be exceeded in a way that could cause danger. Portable appliances — anything with a plug — fall squarely within scope. Landlords also have obligations under the Electrical Equipment (Safety) Regulations 2016, which require that any electrical equipment supplied with a rental property is safe.

How Often Should PAT Testing Be Done?

Testing frequency should be proportionate to the risk. The HSE and the IET Code of Practice for In-Service Inspection and Testing of Electrical Equipment (4th edition) both provide guidance on recommended intervals based on equipment type and environment. These are not legal minimums — they are a sensible starting point for your risk assessment.

Testing Intervals by Environment

Construction sites are a special case. The combination of physical abuse, damp, and damage from other trades means equipment degrades quickly. The IET guidance for 240V tools on a construction site is a one-month visual inspection cycle and a formal PAT test every three months. Many contractors test even more frequently on long-running sites.

When to Test More Frequently

Risk assessment should override any default interval. Test more frequently if: equipment is used intensively (multiple shifts), it operates in a wet or dusty environment, it is regularly moved or transported, or it has previously failed testing. User checks — a quick visual inspection before use — should happen daily or before each use regardless of the formal testing schedule.

Class I vs Class II: Why It Matters for Testing

Understanding the difference between Class I and Class II equipment is fundamental to PAT testing. The class determines both the protection method and which tests you need to run.

Class I Equipment

Class I appliances rely on two things for protection: basic insulation and a protective earth connection. If the insulation fails, fault current flows to earth via the earth conductor, tripping the circuit breaker or blowing the fuse. Examples include most power tools, kettles, toasters, and older IT equipment. The earth path is critical — which is why earth continuity testing is mandatory for Class I equipment.

For Class I items you need to run:

• Earth continuity test (typically <0.1Ω plus lead resistance)
• Insulation resistance test (typically >1MΩ at 500V DC)
• Visual inspection
• Functional check

Class II Equipment

Class II appliances (marked with the double-square symbol) use reinforced or double insulation as their sole protection. There is no earth pin on a Class II plug (or the earth pin is non-functional). Examples include most modern power tool chargers, laptop power supplies, and many small appliances. Because there is no earth to test, the earth continuity test is not applicable — but insulation resistance testing still is.

Pass/Fail Criteria

PAT testing is not black and white. Results must be interpreted alongside the equipment type, its age, and its intended use. That said, the IET Code of Practice gives clear pass/fail thresholds for the standard tests.

Earth Continuity

For Class I equipment, the earth continuity test measures the resistance between the earth pin of the plug and any exposed metalwork on the appliance. The pass criterion varies by how the test is conducted:

• Using a 200mA test current: resistance should be <0.1Ω plus the resistance of the supply lead
• For long extension leads, add 0.1Ω per metre of lead resistance
• Anything above these thresholds is a fail — the earth path cannot be relied upon

Insulation Resistance

Test at 500V DC between live conductors (L+N linked) and earth (for Class I) or the appliance enclosure (for Class II). The minimum pass value is 1MΩ. In practice, healthy equipment often reads well above 10MΩ or off the scale. A reading between 0.5MΩ and 1MΩ is borderline and warrants investigation. Below 0.5MΩ is a clear fail.

Note: some equipment — anything with filters or surge protection, and equipment with heating elements — may show lower insulation readings. Always consult the manufacturer's data before condemning this type of equipment.

Visual Inspection

A significant proportion of faults are found visually before any formal test is run. Automatic fails on visual inspection include: damaged or exposed conductors, cracked or melted plug body, incorrect fuse rating, evidence of overheating, damage to the appliance casing that exposes live parts, or a non-standard plug. Do not overlook the flex where it enters the plug and where it enters the appliance — these are the two highest-wear points.

What to Record on a PAT Test Certificate

Good documentation is what converts a PAT test from a physical activity into a defensible compliance record. A PAT testing certificate should contain enough information for someone else to understand what was tested, how, and what the outcome was.

Mandatory Fields

At minimum your records must include:

• Site address and client name
• Tester's name and qualification/competency
• Date of inspection and testing
• Unique asset ID for each item (label applied to the appliance)
• Appliance description and make/model where known
• Class (I, II, or III)
• Earth continuity result (Class I only)
• Insulation resistance result
• Overall pass or fail
• Next test due date
• Action taken on failed items (removed from service, repaired, disposed)

Keeping Records Useful

A long spreadsheet of pass results is not particularly useful if it takes twenty minutes to locate a specific item's history. Organise records by location within the site (room, floor, department) and use consistent asset IDs that match the labels on the appliances. If an item fails and is repaired or replaced, record both events — the failure and the clearance — so there is a complete audit trail.

For properties where you also carry out fixed wiring work, PAT records complement the Electrical Installation Condition Report (EICR), which covers the fixed installation. Neither document covers both — you need both to demonstrate a complete picture of electrical safety on a site.

How Long to Keep Records

There is no statutory retention period for PAT records, but HSE guidance suggests keeping them until the next test — or longer where equipment has a history of faults. In practice, many businesses retain records for the life of the equipment plus a few years. For insurance purposes, longer is generally better. Cloud-based or digital records are easier to retain and search than paper logs.

Who Can Carry Out PAT Testing

PAT testing must be carried out by a "competent person" — someone with sufficient knowledge and experience to carry out the tests safely and interpret the results correctly. There is no legal requirement for a specific qualification, but in practice most competent testers hold a City and Guilds 2377 or equivalent PAT testing qualification.

The level of competency required scales with the complexity of the equipment and the environment. For straightforward office environments, a trained member of staff using a basic PAT tester may be sufficient. For industrial sites, construction, or healthcare environments, a qualified electrician or specialist PAT tester is the appropriate choice. If you are unsure, default to the more qualified option — the liability falls on whoever signs off the records.

Self-employed electricians carrying out PAT testing for clients should ensure their public liability insurance covers this activity. Some insurers treat PAT testing as a separate trade category — it is worth checking your policy wording.

Published February 2026. This article is for general guidance only and does not constitute legal or professional advice. Always refer to the relevant standards and consult qualified professionals for definitive requirements.