How to PAT test appliances

Portable appliance testing (PAT) plays a key role in keeping workplaces safe by checking that everyday electrical equipment stays in good working order throughout its operational life.

While not every appliance must be tested by law, PAT testing is widely recognised as a best-practice measure under the Electricity at Work Regulations 1989 and related guidance. It helps prevent electric shocks, fires and costly downtime.

This guide explains what PAT testing is for, the legal backdrop, how the testing process works and how to keep good records – giving organisations practical tools to look after their portable electrical equipment with confidence.

What is PAT testing?

Portable appliance testing is the process of checking electrical appliances and their leads to make sure they’re safe to use.

It involves two interlinked stages:

1. A thorough visual examination of the appliance to spot obvious issues like cracked casings, damaged cables or loose plugs
2. A series of electrical tests using specialised equipment to confirm that key safety features – like earth continuity, insulation resistance and polarity – are working properly.

Together, these steps prove that an appliance won’t pose a risk under normal use.

The goal of PAT testing is to prevent harm before it occurs. By picking up on early signs of deterioration, whether they are caused by mechanical stress, environmental factors or routine wear, organisations can intervene early, repairing or replacing faulty equipment. This prevents potential incidents.

In practice, PAT testing schedules are tailored to the operating environment, frequency of use and the risk posed by each appliance, ensuring resources are focused where safety benefits are greatest.

UK legal requirements and HSE guidance

PAT testing isn’t needed for every portable appliance, but employers and dutyholders are still expected to ensure electrical safety under the Electricity at Work Regulations 1989. These regulations require that all electrical systems are maintained to prevent danger.

According to the Health and Safety Executive (HSE), PAT testing is a way to fulfil this obligation. It offers detailed advice in its Portable Appliance Testing FAQs.

The broader legislative framework includes the Health and Safety at Work etc. Act 1974, which imposes a general duty on employers to ensure the health and safety of employees and others affected by work activities. Under this Act, failing to take reasonable steps – including PAT testing where appropriate – can lead to enforcement notices or prosecution.

For higher-risk environments like construction sites or manufacturing plants, guidance from the Approved Code of Practice L22 emphasises the importance of rigorous electrical inspection routines, including in-service testing for portable tools.

The IET Code of Practice for In-Service Inspection and Testing of Electrical Equipment (often referred to as BS IEC 60364-6) sets out clear guidance on inspection regimes, test methods and testing intervals. While it’s not legally binding, following the Code is seen as good evidence of “due diligence” and best practice – something that can be crucial in the event of an incident or regulatory audit.

Which appliances need PAT testing?

Not all electrical devices demand the same level of scrutiny. Broadly, PAT testing applies to any portable or movable electrical equipment that connects via a plug and lead to the fixed electrical installation. Typical examples include:

• Desktop computers
• Kitchen appliances
• Portable heaters
• Power tools
• Audio-visual equipment

The following categories are exempt or follow modified routines:

• Double-insulated (Class II) appliances, such as many hairdryers and power drills, lack an earth connection. They rely on reinforced insulation – so while they still need visual and functional checks, earth continuity testing isn’t required.
• Stationary equipment, like ovens, lighting installations and fixed wiring systems, falls outside of PAT test scope. Instead, it’s covered by fixed-installation inspections and testing under BS 7671.
• Low-voltage or extra-low-voltage devices, like those powered by a transformer, often carry a lower risk. A visual check may be enough unless a workplace policy calls for more.
• Equipment used in medical locations is treated differently because patient safety is at stake. It demands specialised testing regimes under HTM 06-01, with higher frequency and more stringent criteria.

A good way to decide what to include is to create an asset register. Categorise equipment by class, voltage, portability and risk profile. This register then drives both the volume and frequency of tests, ensuring that resources focus on items most likely to present hazards if left untested.

Types of PAT testing: visual, manual and electrical

PAT testing brings together three approaches, each designed to uncover a different type of fault.

1. Visual inspection

The first line of defence involves examining the appliance, plug and cable for signs of mechanical damage, overheating, improper modification or incorrect assembly.

Inspectors look for cracks, exposed conductors, missing earth pins or strain-relief failures.

This inspection can be carried out by any competent individual – including trained users – and should come before (and inform) electrical tests.

2. Manual (functional) testing

If nothing looks out of place, simple functional checks confirm that controls, switches and safety features work correctly.

For example, a kettle can be switched on to see if the thermostat engages, or a power tool can be run briefly (without load) to check the motor spins smoothly.

3. Electrical testing

A PAT tester is used to perform measurements such as:

• Earth continuity – ensures that the earth conductor connects the metal parts of a Class I appliance back to the supply earth with low resistance, typically below 0.1 Ω.
• Insulation resistance – verifies that live and earth conductors remain isolated, with resistance usually exceeding 1 MΩ to guard against leakage currents.
• Polarity check – confirms that live, neutral and earth conductors are correctly wired within plugs and appliances.
• Earth leakage (optional) – measures leakage currents to earth, which is especially important for medical or IT equipment.
• Load testing (optional) – applies a small load to the appliance to check how it operates under working conditions. This is often needed for power tools.

Using all three approaches together spotlights obvious faults and those that are more hidden, giving users confidence that appliances are safe to use.

Frequency of testing based on risk and usage

Setting appropriate test intervals is key to finding the right balance between safety, cost and operational convenience. While BS IEC 60364-6 offers industry benchmarks, organisations typically tailor frequencies according to three main factors:

1. Environment
2. Equipment type
3. Frequency of use

In low-risk office environments where appliances are rarely moved and used very little, annual visual inspections might be enough, with full PAT tests every two years.

Handheld tools in industrial settings, which endure rough handling, dust and vibration, often need visual and electrical testing every three to six months.

Devices on construction sites, where the risk of damage is high, may require even more frequent checks, sometimes before each use.

A risk-based approach is key when setting intervals. Items used outdoors, in harsh conditions or in public-facing settings warrant shorter cycles, while infrequently moved devices in fixed locations can be tested less often.

Organisations should review their schedules annually, taking into account test findings, incident reports and changes in usage patterns, to ensure the process remains fit for purpose.

Equipment needed for PAT testing

Successful PAT testing depends on reliable instruments, accessories and reference materials. Keeping this kit in good order is essential to avoid false passes or missed faults, putting safety at risk.

The essentials typically include:

• PAT tester – a calibrated device that can perform earth continuity, insulation resistance, polarity and leakage tests. Options range from simple pass/fail handheld devices to advanced machines with asset-tracking software and network connectivity.
• Test leads and probes – colour-coded, insulated leads and crocodile clips for earth bond testing and other measurements. Probes must be in good condition, with no exposed wiring or loose connectors.
• Dummy loads (if required) – some appliances, particularly motorised tools, benefit from a standardised load during testing to simulate operating conditions.
• Test record forms or software – asset registers, test labels and digital management platforms help log results, automate reminders and generate compliance reports.
• Reference guides – the IET Code of Practice (BS IEC 60364-6) and manufacturer manuals provide test values, durations and criteria for different appliance types.
• Calibration certificates – PAT testers should be calibrated annually by an accredited lab to ensure measurement accuracy, with certificates kept on record to prove compliance.

How to conduct a visual inspection step by step

Before any electrical measurements, every appliance should undergo a systematic visual inspection.

Start by disconnecting the equipment and placing it on a well-lit, stable surface. Then, follow these steps:

1. Inspect the plug – ensure that the outer sheath is clamped securely, pins are straight and undamaged, and the fuse (in fused plugs) is appropriate and properly seated.
2. Check the cable – follow it from the plug to the appliance casing, looking for cuts, nicks, crushing or signs of overheating such as browning or stiffness. Pay particular attention to areas where the cable enters the plug or appliance, as these spots are the most strained.
3. Inspect the casing – check for cracks, dents or loose panels that could expose live parts. Hinges, vents and seals should close tightly, preventing dust or moisture from getting in. Open the appliance where safe and instructed by the manufacturer – using insulated tools if necessary – and look for evidence of water damage, corrosion or pest activity inside.
4. Assess accessories and attachments – docking stations, chargers and connecting leads should be checked for the same range of faults.

If you find a defect during the visual inspection, remove it from service right away. This should be followed by repair, if possible, or disposal. Document your findings, even for minor issues, to support trend analysis and targeted user training.

How to carry out electrical tests safely

With the visual check complete, the appliance is ready for electrical testing.

Always ensure that the test environment is dry and well-ventilated, and that you have been trained on how to operate the PAT tester.

Start by consulting the test sequence recommended by the manufacturer. It will typically follow this order: earth continuity > insulation resistance > polarity > earth leakage (if applicable).

1. Set up connections – connect the PAT tester’s earth lead to the appliance’s earth point – often a metal part of the casing – using a crocodile clip or probe. Attach the live and neutral leads to their respective terminals in the plug or at the appliance entry point.
2. Select test settings – choose the right test voltage for insulation resistance (usually 500 V DC for Class I equipment, 250 V DC for Class II). Observe test durations as specified – usually one second for continuity and one minute for insulation resistance.
3. Run the tests – check that the tester displays stable readings. Between tests, allow the appliance to return to its normal state, as repeated back-to-back high-voltage insulation tests can stress components. Always discharge stored energy – particularly in capacitive circuits – before handling.

If the results fall outside of pass thresholds, label the appliance as “failed” and remove it from service for repair or safe disposal. Never allow an item to pass the functional check if it has failed a safety test.

A methodical workflow is vital: use checklists, stick to manufacturer guidance and wear the right personal protective equipment. Always keep clear of live terminals once a test has started.

Interpreting test results and pass/fail criteria

Understanding what constitutes a “pass” or “fail” is central to reliable PAT testing.

Typical acceptance criteria are as follows:

• Earth continuity resistance – for Class I appliances, resistance should not exceed 0.1 Ω for cords up to 2.5 metres, increasing marginally for longer cables in line with IET guidance.
• Insulation resistance – a minimum of 1 MΩ at the specified test voltage indicates adequate insulation. Some high-voltage or sensitive equipment may require higher thresholds.
• Polarity – live, neutral and earth conductors must be correctly identified. Any reversed or missing conductor fails immediately.
• Earth leakage current – if measured, leakage should remain below 0.75 mA for Class II and 3.5 mA for Class I appliances, though stricter limits apply in medical contexts.

When results fall within these parameters, the appliance earns a “pass” status and can be returned to service. If any measurement falls outside tolerance, a clear fail indication will be displayed – often accompanied by a sound or red light. In this case, the equipment must be isolated.

Record both pass and fail readings, noting any anomalies for follow-up action. If you see readings that are only just within limits – especially if this happens repeatedly – it could point to gradual deterioration, and it’s best to act early rather than wait for a complete failure.

Labelling and record-keeping

After each test, affix a durable sticker to the appliance indicating the test date, the due date of the next test and the tester’s ID or code. Stickers should be heat, moisture and abrasion resistant to remain legible over time.

Failed appliances must carry a prominent “do not use” label until repaired and retested.

Organisations should also maintain a central test record, whether in paper logbooks or digital platforms. Records should normally be kept for three to five years to show due diligence and to support investigations in the event of an incident.

Each entry should include:

• The appliance ID (asset tag or serial number)
• Type of test performed
• Test results
• Name of tester
• Calibration status of the equipment used

Digital solutions often offer handy extras like automatic reminders, dashboards and downloadable compliance reports, making audits and oversight much simpler.

Integrate PAT data with broader maintenance systems to ensure that test requirements are visible alongside routine service schedules.

Common faults and how to spot them

Some faults show up again and again during PAT inspections, and spotting them quickly can save time and cut risk.

• Cables – fraying or exposed conductors, slight discolouration at frequent bend points, and splits you can feel by running a hand along the cable.
• Plugs – loose or heat-melted pins (often visible at the pin bases), and poorly fitted replacements with the wrong fuse size, leading to non-symmetrical bodies or protruding fuse holders.
• Inside appliances – dust build-up around vents and switches that can cause partial short circuits, and bulging capacitors (rounded tops/casings) signalling imminent failure.
• Strain relief – cable clamp no longer gripping the outer sheath, letting inner conductors move and stress connections.
• Extension leads – faults isolated to a single socket that only appear under load. In these cases, test each outlet individually.

Knowing these recurring patterns helps testers focus their visual inspections and electrical tests on the most vulnerable components, streamlining the process without compromising safety.

Who can carry out PAT testing? Competence explained

“Competence” for PAT testing is about having the right knowledge, skills and experience to complete the tasks.

The Electricity at Work Regulations require that only “authorised persons” carry out work on electrical equipment – people who understand the following:

• The principles of electricity
• How to operate test instruments
• The safety implications of each test

Many organisations use external contractors certified by professional bodies such as the National Inspection Council for Electrical Installation Contracting (NICEIC) and the Electrical Contractors’ Association (ECA). These bodies run strict competence schemes.

For in-house testing, staff need structured training covering the following:

• Electrical theory
• Relevant standards (BS IEC 60364-6)
• The correct use of PAT testers
• How to interpret results

Training providers offer courses ranging from one-day introductions to comprehensive competency programmes. These providers should be accredited by the Energy & Utilities Skills Register or the Institution of Engineering and Technology (IET).

Competence isn’t “once and done”. Refresher sessions, observed practice and periodic knowledge checks keep staff up to date with changing standards and good practice.

Ultimately, organisations are responsible for ensuring that anyone performing PAT testing is competent and authorised to do so, and that they operate within a clear framework of roles and responsibilities set out in company procedures.

PAT testing in schools, offices and rental properties

PAT testing requirements vary depending on the environment.

Schools

With equipment constantly handled by both staff and students, the chance of accidental damage is high.

Best practice is to carry out visual inspections at the start of each term, with full PAT tests on computers, projectors and kitchen appliances at least annually. For high-usage areas like sports halls, more frequent checks can reduce downtime and help keep staff and students safe.

Offices

Offices are generally lower-risk settings, so testing intervals can be longer. However, the large quantity of electrical equipment – PCs, monitors, printers and desk lamps – means scheduling needs to be efficient.

Many organisations align PAT testing with staff moves or office refurbs, combining plug-in checks with workspace changes to minimise disruption.

Rental properties

Landlords and letting agents must comply with the Electrical Safety Standards in the Private Rented Sector Regulations 2020. These standards do not explicitly require PAT testing, but they mandate that electrical installations are inspected by a qualified person at least every five years.

Many landlords choose to include PAT tests of portable appliances as part of the inventory handover process. This reduces their liability for faults that occur during the tenancy.

Maintaining compliance between tests

Testing an appliance is only half the job. Keeping it safe between formal inspections is equally important.

Encouraging end-users to carry out quick pre-use checks, like spotting frayed cables, loose plugs or odd noises, adds an extra layer of protection. Simple reminders – posters in shared spaces or prompts on intranet dashboards – help staff remember to report defects straight away so faulty items are taken out of action before they cause harm.

PAT testing should also link into regular maintenance routines. For example, a monthly check of labels or a review of upcoming test dates helps keep programmes on track. Facilities management software or digital compliance tools can automate reminders and escalate overdue tests. They can also generate reports that keep management in the loop.

PAT testing for new and second-hand equipment

New appliances usually have a manufacturer certification confirming they meet design standards – so PAT testing isn’t strictly necessary for these. However, carrying out a visual inspection to catch damage from transit, incorrect wiring or missing fuse ratings is still worthwhile. Many testers go a step further and run a reduced-scope test, checking continuity and polarity before putting new equipment into service.

Second-hand or refurbished devices present a higher risk and should be checked more thoroughly. A full PAT test, combined with a stripped-down internal inspection where safe, can uncover hidden faults like repairs with the wrong parts or altered cable lengths. Recording where the item came from, along with any service history, in the asset register makes future assessments easier.

In both cases, clearly labelling items as “New – Visual Only” or “Second-Hand – Full Test” helps testers apply the correct test regime and keeps audit trails tidy.

Using technology and software for PAT management

Modern PAT testers increasingly use software platforms that make asset tracking, test scheduling and compliance reporting far easier. They can use QR codes or RFID tags on appliances to scan devices, retrieve test history instantly, update records in real time and set automated reminders for retesting. Cloud dashboards then give facilities managers a clear view of coverage, failure rates and upcoming workloads, helping them plan resources proactively.

The data these systems generate can be just as valuable as the tests themselves. Advanced analytics reveal patterns, like particular models or locations producing more failures, guiding preventive maintenance or purchasing decisions. Linking PAT results into wider maintenance management systems (CMMS) means they also feed into asset lifecycles, budget forecasting and risk registers.

For larger organisations with hundreds or thousands of appliances, these digital tools cut admin and boost efficiency.