PAT testing — Portable Appliance Testing — is the examination of electrical appliances and equipment to check they are safe to use. It usually combines a visual inspection with electrical tests carried out using a PAT tester.
Here is the part most people get wrong: “PAT testing” is not itself a legal requirement in UK law. The legal duty is to maintain electrical equipment so it does not cause danger. PAT testing is simply one well-established way of meeting that duty — and the Health and Safety Executive is clear that it is often done far more often than necessary.
This guide explains what PAT testing actually involves, what the law really says, who can do it, and how often it genuinely needs doing.
What does PAT stand for?
PAT stands for Portable Appliance Testing. Strictly, the correct term used by the HSE is “in-service inspection and testing of electrical equipment”, because the process covers more than just portable items and involves inspection as well as testing.
“Portable appliance” is broader than it sounds. It generally covers any equipment with a plug that connects to the mains — kettles, computers, printers, extension leads, power tools, floor cleaners, and site equipment.
Is PAT testing a legal requirement?
No — not as such. No UK regulation says “you must PAT test.”
What the law does say is in the Electricity at Work Regulations 1989. Regulation 4(2) requires that:
“As may be necessary to prevent danger, all systems shall be maintained so as to prevent, so far as is reasonably practicable, such danger.”
That is a duty to maintain — it does not specify how, how often, or by whom. PAT testing is one recognised method of demonstrating that maintenance has happened.
Related duties sit in the Management of Health and Safety at Work Regulations 1999 (risk assessment) and the Provision and Use of Work Equipment Regulations 1998 (equipment must be suitable and maintained).
The HSE is direct about the consequence of misunderstanding this: many organisations test everything annually out of habit, at real cost, when a risk-based approach would be both cheaper and safer. Over-testing is not compliance — it is expense without benefit.
What does a PAT test actually involve?
Proper in-service inspection has up to three levels, and the first is the most valuable:
1. User checks
The person using the equipment looks at it before use: damaged cable, cracked plug, scorch marks, loose parts, exposed wires, damaged casing. No instrument and no formal record needed. Most faults are found this way — because they are visible.
2. Formal visual inspection
A more systematic check by someone trained to carry it out. Includes opening the plug (on rewireable plugs) to check the fuse rating, cord grip and terminal connections. Recorded. A large proportion of defects are detected at this stage without any electrical test at all.
3. Combined inspection and testing
Visual inspection plus instrument tests using a PAT tester. Typical tests include:
- Earth continuity — for Class I (earthed) equipment
- Insulation resistance — checking insulation has not broken down
- Polarity — live and neutral connected correctly
- Functional check — the equipment works as intended
Testing alone is not enough. A machine can pass every electrical test and still be dangerous if the casing is cracked or the cable is crushed — which is why inspection matters more than the instrument.
Class I and Class II equipment — what’s the difference?
| Class I | Class II | |
|---|---|---|
| Protection | Basic insulation + an earth connection | Double or reinforced insulation — no earth needed |
| Typical items | Kettles, toasters, microwaves, many power tools, fridges | Many chargers, hair dryers, some drills, laptop PSUs |
| Marking | — | Double-square symbol |
| Key test | Earth continuity + insulation resistance | Insulation resistance |
Class I equipment relies on the earth as its safety net, so a broken earth is a serious fault. Class II relies entirely on its insulation, so damage to the casing matters more.
How often should PAT testing be done?
There is no legally mandated interval. Frequency should come from a risk assessment considering:
- The type of equipment — a handheld drill takes far more abuse than a desktop monitor
- The environment — construction sites, kitchens and workshops are harsher than offices
- How often it is moved — movement damages cables
- Who uses it — equipment used by the public or untrained users needs more attention
- Its history — a model that keeps failing warrants shorter intervals
In broad terms, hand-held equipment on a construction site needs frequent attention; stationary IT equipment in a low-risk office needs very little. The HSE’s guidance INDG236 — Maintaining portable electrical equipment sets out the risk-based approach in detail.
If your organisation tests every laptop charger in a dry office every twelve months, you are almost certainly spending money the HSE would not ask you to spend.
Who can carry out PAT testing?
The requirement is a competent person — not necessarily a qualified electrician.
Competence means having the knowledge and experience to do the task safely, to interpret the results correctly, and to recognise when something is beyond their ability. For user checks and formal visual inspections, a sensible person with appropriate training is usually sufficient. For combined inspection and testing, the person needs to understand the tests, use the instrument correctly, and judge the results — which typically requires specific training.
The most common failure is not a lack of qualifications — it is someone recording a “pass” without understanding what the reading meant.
Do PAT labels have to be used?
Labels are not a legal requirement, but they are useful practice. A label typically shows the test date, the next due date, the tester’s identity, and pass/fail status.
Two cautions worth knowing:
- A pass label is a record of a moment in time — it says nothing about damage that happened afterwards. This is exactly why user checks matter more than the sticker.
- A “next test due” date is your own risk-based decision, not a legal deadline. Equipment does not become illegal the day after it lapses.
What genuinely matters is a record that lets you demonstrate a maintenance regime — what was checked, when, by whom, and what was found.
What equipment needs checking?
Generally, anything that plugs into the mains and is used at work. In practice this includes:
- Handheld tools — drills, sanders, grinders
- Movable equipment — heaters, fans, vacuum cleaners
- IT and office equipment — PCs, monitors, printers, chargers
- Kitchen appliances — kettles, microwaves, fridges
- Extension leads and cables — statistically among the most damaged items and often overlooked
Fixed installations — the building’s wiring, sockets and consumer units — are not PAT testing. They fall under periodic inspection of the fixed electrical installation, which is separate work.
Conclusion
PAT testing is a means, not an end. The legal duty is to keep electrical equipment from becoming dangerous, and the most effective parts of that duty are the cheapest ones: users looking at equipment before they use it, and someone trained carrying out sensible visual inspections at intervals that match the actual risk.
Understand that, and you spend less, test less, and are genuinely safer than an organisation that labels everything once a year and never looks again.
Further reading
- HSE — Portable appliance testing FAQs
- HSE INDG236 — Maintaining portable electrical equipment
- Electricity at Work Regulations 1989
PAT Testing Awareness training
Our PAT Testing Awareness course covers the ground in this guide — the legal position, equipment classes, inspection levels and risk-based intervals — in a short online course you complete at your own pace.
£9 per course. CPD accredited, 100 % online, with a verifiable e-certificate issued on completion. Need more than one? Pay for 2, get 3 — any 3 courses for £18.
Please note: this is a CPD awareness course. Where your role or scheme requires a regulated qualification or licence, that must come from an approved provider — always check your employer’s or scheme’s specific requirements.