If you're a landlord looking at a furnished flat, or an office manager staring at a kitchen full of kettles, monitors, chargers and extension leads, the usual question is simple. What does PAT testing involve, and do I need it?

That question usually comes up when something practical is at stake. A tenant is moving in next week. Your insurer wants evidence that appliances are being maintained. A failed plug has made everyone suddenly notice how many portable electrical items are in daily use. Theoretical explanations are less important than a clear answer on what happens, what's expected, and what to do if something fails.

In plain terms, PAT testing is the inspection and testing of portable electrical appliances to check they're safe to use. It isn't just about plugging a machine into a tester and printing labels. A proper PAT process includes visual checks, electrical tests where appropriate, logging results, marking equipment, and dealing with failures properly. For landlords and businesses in London, that's the part that matters. Safe equipment, usable records, and a clear trail showing you've taken reasonable steps.

Table of Contents

• What is PAT Testing and Why Does It Matter
• Your Legal and Insurance Obligations Explained
  • Who counts as the duty holder
  • What this means in real life
  • What doesn't work
• The Two Core Parts of a PAT Test
  • Visual inspection
  • Electrical tests
• A Detailed Look at the Electrical Tests
  • Class I appliances
  • Class II appliances
  • Leads, polarity and practical judgement
• What to Expect During an On-Site Visit
  • The typical workflow on the day
  • What clients usually notice
  • Labels and immediate outcomes
• Testing Frequency, Costs, and How to Prepare
  • Recommended PAT testing frequencies by risk level
  • Cost trade-offs in London
  • How to prepare for the visit
• After the Test Managing Fails and Compliance Records
  • What happens when an item fails
  • What records you should keep

What is PAT Testing and Why Does It Matter

PAT stands for Portable Appliance Testing. Despite the name, it isn't a single test. It's a structured safety check for electrical items that are plugged in and can be moved, even if they normally stay in one place. That includes obvious items such as kettles, toasters, monitors and extension leads, but also appliances in furnished rentals like lamps, TVs and vacuum cleaners.

For a landlord, PAT testing is a practical way to show supplied appliances haven't just been left to chance. For an office manager, it's a way to keep routine equipment under control before faults become incidents. In both settings, the point is the same. You want to spot damage, misuse, poor repairs and hidden electrical faults before someone gets a shock or a fire starts from a failing appliance.

A lot of people assume PAT is mostly about the machine the engineer carries. In practice, the job is wider than that. The appliance is identified, inspected, tested if needed, labelled, logged and then either left in service or taken out of use if it isn't safe.

Practical rule: PAT testing is best thought of as a maintenance record with safety checks attached, not just a sticker on a plug.

That matters because the sticker alone doesn't prove much if the records are poor, the wrong items were tested, or failed appliances stayed in use anyway. Good PAT work helps you manage risk properly. Bad PAT work creates a false sense of security.

Your Legal and Insurance Obligations Explained

The legal starting point in the UK is the Electricity at Work Regulations 1989. Those regulations require electrical systems and equipment to be maintained so as to prevent danger, and that duty falls on the people responsible for the premises or equipment, including employers and landlords. In practice, PAT testing has become the standard way to show that portable appliances are being checked and maintained sensibly.

Who counts as the duty holder

In day-to-day terms, the duty holder is the person or organisation responsible for the equipment being provided or used. That can include:

• Landlords who supply appliances in a rental property
• Employers responsible for workplace equipment
• Managing agents acting on behalf of a landlord
• Self-employed people using portable electrical equipment at work

The law doesn't say you must perform a PAT test on every item every year. What it does require is that equipment is maintained in a condition that doesn't present danger. PAT testing is the practical method many duty holders use to prove they're doing that in a structured, repeatable way.

What this means in real life

If you provide a microwave, lamp, kettle or extension lead, you need to be able to show you've taken reasonable steps to keep it safe. For landlords, that sits alongside the wider compliance picture, which often includes gas safety, smoke alarms, deposit rules and fixed wiring checks. A useful way to keep that organised is a broader landlord responsibilities checklist, especially if you're managing multiple properties or a furnished let.

Insurance is where many owners get caught out. Policies often expect you to maintain electrical equipment and keep evidence. If there is an incident, insurers and investigators usually care less about whether you used the phrase "PAT test" and more about whether your inspection and maintenance process was competent, documented and acted on.

If you can't show what was checked, when it was checked, and what happened to failed items, your paperwork is weak even if every appliance has a pass label.

What doesn't work

Three habits cause problems again and again:

1. Testing without records. A label on the item isn't enough on its own.
2. Annual testing by default. Some items need closer attention, some don't. Blind repetition isn't the same as risk assessment.
3. Ignoring failures. Once an item has failed, the issue becomes your response, not just the defect.

The legal duty is about preventing danger. The paperwork matters because it proves you did something sensible, not because forms are the point.

The Two Core Parts of a PAT Test

The question 'what does pat testing involve' often prompts an expectation of a technical answer. The clearest answer is simpler. PAT has two core parts. First, a formal visual inspection. Second, electrical testing where the appliance type and condition call for it.

Visual inspection

This is the part people often underestimate. A proper visual check isn't a quick glance across the room. It means handling the appliance, plug and cable and looking for wear, damage, poor repairs and obvious misuse.

A formal visual inspection can identify up to 95% of appliance faults before any test instrument is used, according to this practical PAT guide from DGEC. That's why competent engineers don't rush past this stage.

Typical issues found visually include:

• Damaged plugs with cracks, loose pins or signs of overheating
• Frayed or trapped cables where insulation may be compromised
• Burn marks or scorching around plug tops or appliance inlets
• Incorrect fuses or obvious signs of unsuitable replacement parts
• Cracked casings that could expose live parts or weaken insulation

In rentals, visual faults often come from heavy use, rough handling, or improvised fixes. In offices, the repeat offenders are usually desk fans, extension blocks, monitor leads and kitchen appliances.

Electrical tests

The second part uses PAT equipment to check electrical safety in a more technical way. The exact tests depend on the class of appliance and what the engineer is looking at. Not every appliance gets the same treatment.

What matters is that the electrical testing confirms whether the appliance's protective measures still work as intended. That could mean checking the earth path on a metal-bodied appliance, confirming the insulation barrier is still sound, or verifying that a lead is wired correctly.

A PAT tester supports judgement. It doesn't replace it. If the visual condition is poor, the appliance may already be unsafe before any meter reading appears.

What works well is combining both stages properly. What doesn't work is relying on test readings alone while ignoring obvious physical damage. That's one of the quickest ways to overlook common defects in items people use routinely.

A Detailed Look at the Electrical Tests

The electrical part of PAT testing sounds technical, but the logic behind it is straightforward. The engineer is checking that the appliance's built-in safety protections still do their job if something goes wrong.

Class I appliances

Class I appliances rely on an earth connection for safety. These are often items with exposed metal parts. If a fault makes that metal live, the earth path is there to carry fault current away safely and help protective devices operate.

Two common checks are:

• Earth continuity test. This confirms there is a low-resistance path between the earth pin and the exposed metal parts. In practical terms, the earth conductor has to be intact and reliable.
• Insulation resistance test. This checks that electricity isn't leaking from live parts into places it shouldn't be. Think of it as checking the quality of the appliance's insulating barrier.

If earth continuity is poor on a Class I item, that appliance may look normal but still present a serious shock risk. That's why metal kettles, some desktop equipment and many extension leads need more than a label and a quick glance.

Class II appliances

Class II appliances are double-insulated. They don't rely on an earth connection in the same way, so the earth continuity test is omitted. Instead, the focus shifts to the condition of the insulation that protects the user.

For Class II appliances, PAT testing centres on insulation resistance, often performed at 250V or 500V DC, with a pass limit of over 2MΩ, as described in this Class II PAT testing reference video. In plain English, the test checks that the supplementary insulation is still doing the job that an earth conductor would otherwise help with.

Common Class II items include plastic-cased chargers, many lamps, and a lot of modern small appliances. They often look simpler, but they still need proper inspection because cracked casings, heat damage and poor-quality replacements can undermine the insulation that makes them safe.

Leads, polarity and practical judgement

Extension leads and IEC computer leads deserve extra attention because they get bent, trapped and swapped around. With these items, polarity checks matter. The live, neutral and earth conductors must be in the correct places, especially on rewired or suspect leads.

Functional operation can also matter after the electrical tests. A unit may pass its measured readings but still have a damaged switch, loose connection or intermittent issue in normal use. That's where experienced judgement comes in. PAT testing isn't just about obtaining a pass screen on the tester. It's about deciding whether the item is safe to put back into service under BS 7671-aligned good practice.

What to Expect During an On-Site Visit

A PAT visit is usually more orderly and less disruptive than people expect. In a small office or managed rental, the engineer will normally start by confirming which appliances are yours, which are tenant-owned, and which items need to be included in the record.

The typical workflow on the day

The process usually runs like this:

1. Asset identification. Each appliance is listed or confirmed, often room by room.
2. Visual inspection. The engineer checks the plug, cable, casing and general condition.
3. Instrument testing. Where appropriate, the appliance is connected to a PAT tester.
4. Labelling. Pass or fail labels are attached with identifying details.
5. Logging results. Findings are recorded for the final report.

A competent engineer can usually test an appliance in 2 to 5 minutes, so 50 items in a small office can often be completed in 2 to 4 hours, including logging and labelling, as noted in the earlier linked PAT process guide. That's why preparation matters. If items are accessible and grouped sensibly, the visit moves quickly. If every plug is hidden behind furniture or mixed up with personal equipment, the job slows down.

What clients usually notice

Most disruption comes from access, not the test itself. A kettle is unplugged briefly. A monitor may need to be disconnected for a moment. Extension leads under desks take longer than the appliance plugged into them.

If you're arranging testing through a contractor, ask in advance how they handle asset numbering, failed item isolation and final reporting. For example, a service such as PAT testing for landlords, offices and businesses should make clear what gets logged and what paperwork you receive afterwards.

This short video gives a feel for the process in a live setting:

In a well-prepared site, the engineer spends time testing. In a poorly prepared site, the engineer spends time moving furniture, tracing plugs and separating business equipment from personal items.

Labels and immediate outcomes

At the end of each item's check, it will normally be marked to show its status. A pass label helps identify that the appliance has been inspected. A fail label matters even more, because it signals that the item shouldn't stay in use.

That immediate clarity is useful for offices and rentals alike. Nobody has to rely on memory later. The appliance itself tells the story, and the report backs it up.

Testing Frequency, Costs, and How to Prepare

The question that follows "what does pat testing involve" is usually "how often should I do it?" The honest answer is that there isn't one interval that suits everything. Good PAT scheduling is based on risk, not habit.

In practice, frequency depends on how the equipment is used, who uses it, where it lives, and how likely it is to suffer damage. A kettle in a shared office kitchen is a different risk from a rarely moved monitor in a low-use admin room. If you want a broader view on electrical testing intervals, this guide on how often electrics should be tested helps place PAT alongside other inspection duties.

Recommended PAT testing frequencies by risk level

These intervals reflect the risk-based ranges described in the verified guidance. They aren't a substitute for judgement. If an item is damaged, heavily used or in a harsher environment, it may need attention sooner.

Cost trade-offs in London

There isn't a single standard market price, and if anyone gives you a universal figure without seeing the site, treat that cautiously. In London, PAT pricing usually depends on the number of items, access, whether there is a minimum callout, and whether testing is combined with other compliance work.

Two practical pricing models are common:

• Per-appliance pricing works well when the item count is clear and access is straightforward.
• Half-day or day-rate pricing often makes more sense when the site is larger, spread across rooms, or mixed with asset logging and remedial work.

What works financially is matching the interval to the risk. What doesn't work is over-testing low-risk equipment just because "annual PAT" sounds tidy on paper. If your equipment profile is mostly low-risk IT kit, a competent contractor should be able to discuss a more sensible inspection pattern instead of pushing the same timetable for every item.

How to prepare for the visit

A little preparation saves time and avoids missed items.

• Make appliances accessible. Clear desks, cupboards and kitchen corners where plugs and leads are hard to reach.
• Separate owner-supplied and personal items. This matters in rentals and shared offices.
• List what you expect to be tested. Even a simple room-by-room note helps.
• Flag known issues early. If a plug overheats or a lead has been trapped, say so before testing starts.
• Arrange access to locked rooms. Delays usually come from keys, not test equipment.

For landlords, it also helps to align PAT with tenancy turns, inspections and fixed wiring compliance so you aren't paying for repeated visits that could have been coordinated.

After the Test Managing Fails and Compliance Records

The most important part of PAT testing often starts after the engineer has finished. If an appliance fails, the issue is no longer just electrical safety. It's what you did next, and whether you can prove it.

A failed appliance must be communicated to the owner and must not be used until repaired and retested, as explained in this guidance on what happens when PAT testing finds a problem. That post-test workflow is where due diligence is either demonstrated properly or undermined.

What happens when an item fails

The correct response is usually straightforward:

• Remove it from service. Don't leave it plugged in for convenience.
• Mark it clearly. A visible "Do Not Use" status avoids confusion.
• Decide whether to repair or replace. Minor lead or plug issues may be repairable by a qualified person. Some items aren't worth keeping.
• Retest before reuse. Repair isn't the end of the process. The item must be checked again before it goes back into service.

For landlords, this matters because supplied appliances can create avoidable disputes if a tenant keeps using something already identified as unsafe. For businesses, it matters because staff often assume that if an item is still on site, it's still approved.

The liability problem usually isn't the failed test itself. It's the gap between the failed test and the action taken afterwards.

What records you should keep

You should expect a PAT record that identifies the appliance, its result, and enough information to trace what happened. In practice, useful records often include the item description, location, asset ID, test outcome, label status and notes on any remedial action.

That matters for internal safety management, insurance queries and external scrutiny. If you ever need to show how you handled evidence of a defect, the principles behind how organisations properly manage audit evidence are relevant here as well. The point is simple. Keep records that are clear, retrievable and linked to actions taken, not just test dates.

For landlords, PAT records should sit alongside the rest of the property's electrical file, especially the fixed installation paperwork. If you're already arranging a fixed wiring inspection, keep the PAT schedule connected to the property's EICR certificate requirements in London so your compliance documents make sense together rather than living in separate folders no one updates.

Good record-keeping turns PAT from a one-off visit into an ongoing safety system. Poor record-keeping turns it into a stack of labels with no defensible history.

If you need PAT testing arranged for a London rental, office or managed property, Electricians London 247 provides PAT testing as part of its wider BS 7671-compliant electrical services, alongside EICRs and remedial works. The practical benefit is keeping inspection, reporting and any follow-up electrical work in one place so you can deal with safety issues promptly and keep your records straight.