What is PAT testing? The plain-English guide to portable appliance testing

Published 7 September 2026 · updated 7 September 2026 · SparkCerts guides for UK electricians

Portable appliance testing, PAT for short, is the in-service inspection and testing of portable electrical appliances to confirm they are safe to keep using. The kettle in the office kitchen, the 110V grinder on site, the extension lead that has lived in the back of a van for three years: all of them are portable appliances, and all of them are what this guide covers. It is written for the electricians who do the testing and for the office managers, landlords and site agents who have been told they need it and want the plain version. One clarification before anything else: SparkCerts is software for electricians, not a testing service, so what follows is definitions and honest numbers rather than a pitch.

What PAT testing actually involves

Every test starts with a formal visual inspection, and for good reason: most faults are found by eye. The inspector checks the plug for correct wiring and a fuse of the right rating, runs the full length of the lead looking for damage, checks the casing for cracks and missing screws, and looks at how the appliance is actually used. A lead routed under a door or across a walkway will fail eventually whatever its test readings say.

Then come the instrument tests, and which ones apply depends on how the appliance protects its user. A Class I appliance relies on earth for its protection: metal casing, three-core lead, the earth pin doing real work. It gets an earth continuity test to prove that path is sound, then an insulation resistance test. A Class II appliance is double insulated, marked with the square-in-a-square symbol, and needs no earth, so it takes an insulation test only. Earth leakage and functional checks are optional additions where the appliance or the environment calls for them.

In a mixed office the whole job, inspection, tests, pass label and register entry, runs at about three minutes per item. That is the number to reach for when someone asks how long a visit will take: 30 items is roughly an hour and a half of testing, plus setup and travel. If you are the one quoting the job, the PAT testing price calculator turns those minutes into an hourly rate, and our PAT testing cost guide sets out what the market charges.

Does PAT testing need to be done annually?

No. No UK regulation sets a fixed interval, and none of them uses the word annual. The legal duty sits in regulation 4(2) of the Electricity at Work Regulations 1989, which requires electrical equipment to be maintained so as to prevent danger. How often that maintenance happens is a judgement, not a date on a calendar.

The judgement has a framework. The IET Code of Practice, rewritten for its fifth edition in 2020, sets out a risk-based approach: the interval depends on the class of equipment, what it is used for, and the environment it works in. A kettle in a quiet office and a 110V transformer tool on a building site are both portable appliances. One of them gets looked at next month. Anyone selling a legal annual test is repeating a myth or trading on it, and the myth is stubborn because annual billing is convenient.

How often should appliances be PAT tested?

The intervals below are typical starting points drawn from the IET Code of Practice. They are not law, and they assume normal use: equipment that is abused, moved daily or used by the public earns itself shorter intervals, and the user's own risk assessment has the final say.

Two patterns are worth noticing. Hand-held, Class I and site equipment clusters at the short end, because those are the appliances that get dropped, dragged and unplugged for a living. Fixed office kit clusters at the long end, where a quick user check between formal tests does most of the work.

Who needs PAT testing?

• Employers. The maintenance duty covers equipment provided for people at work, from the workshop bench to the staff kitchen.
• Landlords. Appliances supplied with a tenancy need evidence that they were safe when let. Scotland makes it explicit under the repairing standard; elsewhere it is the cleanest proof a landlord can hold. Our guide to landlord EICR requirements covers the fixed wiring side, which runs on its own timetable.
• Event venues and hire companies. For most venues and hirers, a valid test is a condition of plugging anything in, and they will ask for the paperwork.
• Holiday lets and HMOs. Supplied appliances plus a constant turnover of users is exactly the combination the risk-based system exists to catch.
• Contractors on client sites. Many sites now want in-date test records for tools before they are plugged in, so the register travels with the kit.

What you get at the end

Three things. First, a register of results: every appliance identified, the tests applied, pass or fail, and the date of the next test. Second, labels on the items themselves, pass or fail, with the retest date where it helps. Third, and this is the part that matters later, a record that can be produced on demand. The register is what an insurer asks for after a claim, what an auditor asks for on a site check, and what a client's procurement department asks for before you are allowed on their premises. A test nobody can evidence might as well not have happened.

The register is also where the paperwork usually falls apart: results in one file, the invoice in another, the certificates in a third. SparkCerts keeps the PAT register alongside the certificate and the invoice for the same job, so when someone asks, it is one record rather than an afternoon of searching. The testing is yours; the paperwork should not be a second job.

Common questions

What does PAT testing stand for?

Portable appliance testing. The name refers to testing portable appliances in service, meaning while they are in use rather than new out of the box. The IET Code of Practice now calls it in-service inspection and testing of electrical equipment, because the same principles cover equipment that is not strictly portable, but PAT testing remains the name everyone uses.

Does PAT testing need to be done annually?

No. There is no law or regulation that sets an annual interval. The duty under the Electricity at Work Regulations 1989 is to maintain equipment to prevent danger, and the IET Code of Practice sets risk-based intervals that depend on the equipment class, how it is used and where. Office IT can run a 48-month cycle; a construction site tool needs checking every three months.

How often do you PAT test?

It depends on the appliance and where it works. Typical starting points from the IET Code of Practice: 110V site tools every 3 months, hand-held Class I tools and commercial kitchen equipment every 6 to 12 months, and office IT and kettles anywhere from 12 to 48 months. The user's own risk assessment has the final say.

How long does PAT testing take?

A mixed office runs at about three minutes per appliance, including the visual inspection, the instrument tests, the pass label and the register entry. So a 30-item office is roughly an hour and a half of testing, plus setup and travel. IT equipment with simple leads is quicker; workshop kit with guards and awkward access is slower.

Is PAT testing a legal requirement?

There is no law that says PAT test, and none that says annually. The legal duty is the Electricity at Work Regulations 1989, regulation 4(2): electrical equipment must be maintained to prevent danger. For employers that covers equipment provided for people at work; for landlords it sits alongside general duties and, in Scotland, the repairing standard. PAT testing is the accepted way of evidencing that maintenance.

Can I do my own PAT testing?

Yes, if you are competent to do it. The Electricity at Work Regulations require the person doing the work to have the technical knowledge and experience, and the IET Code of Practice expects formal qualification or equivalent training for combined inspection and testing. A short course covers the basics, and you also need a calibrated tester and a proper register of results.

How much does PAT testing cost?

Most testers charge a minimum visit fee of £50 to £90, covering the first 20 to 30 appliances, then £1 to £3 per item above that, with the rate falling on larger sites. A 25-item office therefore pays the minimum fee, and a 100-item site pays closer to £1 an item. The visit itself drives the price of small jobs.

What is a Class I appliance?

A Class I appliance has basic insulation and relies on an earth connection for protection: metal casing, a three-core lead, an earth pin doing real work. Kettles, irons and most metal-cased power tools are Class I, and they get an earth continuity test as well as an insulation test. Class II appliances are double insulated and marked with the square-in-a-square symbol.