What is PAT Testing?

PAT testing — Portable Appliance Testing — is the in-service inspection and testing of electrical appliances to check that they are safe to use. It combines a visual inspection with a series of electrical tests carried out using a PAT tester.

PAT testing is the practical way UK businesses meet their legal duty to maintain electrical equipment in a safe condition. This guide explains what it involves, what the law says, which tests are carried out, and how software can keep the whole process manageable.

What is a PAT test?

A PAT test checks an electrical appliance for damage, deterioration, or faults that could cause electric shock, fire, or injury. It is not a single test but a process with two stages:

1. Visual inspection — checking the plug, cable, connector, and casing for damage, taped joints, fraying, or signs of overheating. Around 80% of faults are found by a thorough visual inspection alone.
2. Electrical testing — using a calibrated PAT tester to verify the safety of the appliance's construction and condition.

Is PAT testing a legal requirement?

There is no single Act that says "you must PAT test". Instead, a set of regulations place a duty on employers to make sure electrical equipment is maintained safely. The key ones are:

• The Health and Safety at Work Act 1974 (HSWA) — places a general duty on employers to ensure the health, safety, and welfare of their employees, including the equipment they use.
• The Electricity at Work Regulations 1989 (EAWR) — Regulation 4(2) states that all electrical equipment must be maintained to prevent danger. This is the regulation most commonly cited as the legal basis for PAT testing.
• The Management of Health and Safety at Work Regulations 1999 — requires employers to assess risks and take reasonable steps to control them.

Because the law uses terms like "maintained to prevent danger" rather than prescribing a fixed schedule, the accepted technical guidance is the IET Code of Practice for In-Service Inspection and Testing of Electrical Equipment (5th Edition). It explains what to inspect, how often, and how to record the results.

Who should PAT test?

Any business, landlord, or organisation that provides electrical equipment to employees, tenants, or the public has a duty to maintain it safely. This typically includes:

• Offices and commercial premises
• Landlords and property managers (for appliances supplied to tenants)
• Factories, workshops, and construction sites
• Schools, care homes, and public buildings
• Hire companies, venues, and production companies — equipment hired out must be safe each time it leaves the premises

Testing must be carried out by a competent person — someone with the knowledge, training, and experience to carry out the work safely and understand what the results mean. The IET Code of Practice makes it clear that the competence requirement applies whether testing is done in-house or by a contractor.

Appliance classes

Appliance classes determine which electrical tests are needed. The three classes found in the workplace are:

• Class I — appliances with a metal casing that rely on an earth connection for safety (for example kettles, fridges, many power tools). Require earth continuity, insulation, and leakage tests.
• Class II — double-insulated appliances with a plastic casing and no earth connection (for example laptops, hairdryers, most modern chargers). Require insulation and leakage tests, but no earth test.
• Class III — appliances powered by SELV (Separated Extra Low Voltage) under 50V (for example some laptop supplies and low-voltage equipment). Tested to a reduced set of checks.

Each appliance should carry a mark showing its class — Class II is marked with the double-square symbol.

The tests performed

NETS PAT records the standard test sequences used by PAT testers. A typical sequence for each class looks like this:

• Earth continuity (Class I) — verifies the earth connection between the plug and exposed metal casing is continuous and low resistance.
• Insulation resistance (Classes I and II) — applies a voltage between the live conductors and earth/accessible parts to confirm the insulation is sound.
• Leakage current — measures current leaking to earth or the casing under normal operation.
• Polarity — confirms the live, neutral, and earth connections in the plug are wired correctly.
• Visual check — always performed, checking the plug, cable, and casing for damage.

Test results are compared against thresholds from the IET Code of Practice. NETS PAT applies these automatically:

• Earth continuity — pass if ≤ 0.1Ω (plus test lead compensation where applicable)
• Insulation resistance — pass if ≥ 2.0 MΩ (0.3 MΩ minimum where an element is present)
• Leakage current — pass if ≤ 0.75 mA

Managing PAT testing with software

Once you move beyond a handful of appliances, spreadsheets stop being practical. PAT testing software manages the whole cycle:

• Asset registers — every appliance, its location, class, and test history in one place
• Rapid testing — record tests with a USB or Bluetooth barcode scanner as you work
• Tester data import — upload results from your PAT tester (CSV or PATGuard .SSS) and let the software build assets, certificates and clients for you
• Automatic pass/fail — results are compared against IET thresholds instantly
• Certificates and labels — branded PDF certificates and barcode labels generated automatically
• Retest scheduling — risk-based intervals flag appliances that are due for retesting

NETS PAT is built specifically around the IET workflow, and covers every step from scan to signed certificate. See the full feature list, or start a free account — no card required.

Frequently asked questions

How often should PAT testing be done?

Frequency depends on the type of equipment and the environment it is used in. There is no single statutory interval — it is set by risk assessment, with guidance ranging from three months for high-risk hire equipment up to four years for low-risk office IT. See our PAT retest intervals guide.

Is PAT testing mandatory by law?

There is no specific "PAT testing law", but the Electricity at Work Regulations 1989 require electrical equipment to be maintained to prevent danger. PAT testing is the standard, recognised way of meeting that duty.

Do landlords have to PAT test?

Landlords must ensure appliances supplied as part of a tenancy are safe. This duty comes from the Landlord and Tenant Act 1985 and the Consumer Protection Act 1987, and PAT testing is the accepted way to evidence it.

Can I do my own PAT testing?

Yes — if you are a competent person with the right training and calibrated equipment. Many businesses test in-house and use contractors for periodic external audits.

How much does PAT testing cost?

Per-item costs vary widely depending on volume, travel, and whether it's in-house or contracted out. See our PAT testing cost guide for typical market rates.

What happens to failed appliances?

A failed appliance should be taken out of service immediately, labelled as failed, and either repaired or disposed of by a competent person. NETS PAT records the failure, removes it from your active inventory, and keeps a full history.