PAT Testing Frequency: Recommended Intervals by Appliance Type
How often should you PAT test your equipment? There is no single legal answer. PAT testing frequency depends on the type of equipment, the environment it's used in, and how heavily it's used. Anyone who tells you "everything needs testing every year" is either misinformed or selling annual testing contracts.
This guide gives you the recommended intervals based on the IET Code of Practice, the industry standard for in-service inspection and testing of electrical equipment in the UK.
There is no fixed legal frequency
The Electricity at Work Regulations 1989 require you to maintain electrical equipment to prevent danger. They do not specify how often. The HSE's guidance document INDG236 confirms this — there is no legal requirement for fixed PAT testing intervals.
The IET Code of Practice (5th Edition) provides suggested initial intervals based on equipment type and environment. These are starting points, not rules. You're expected to adjust them based on your own experience and failure data.
For a full explanation of the legal framework, see our guide on what UK law actually says about PAT testing.
Three levels of inspection
Before looking at the intervals, you need to understand the three levels of checking defined by the IET Code of Practice. They're not interchangeable.
User checks — The person using the equipment looks it over before switching it on. Check the cable for damage, make sure the plug isn't cracked, confirm nothing looks burned or melted. No formal recording needed, but staff should know what to look for.
Formal visual inspection — A more thorough visual check by someone competent. Covers the plug wiring (if it's a rewirable plug), the cable condition, the appliance casing, and any signs of overheating or damage. Recorded on your PAT testing record sheet. No test instruments required.
Combined inspection and testing — A formal visual inspection plus electrical tests with a PAT tester. Earth continuity, insulation resistance, and where applicable, protective conductor current or touch current. This is what most people mean by "PAT testing."
Recommended PAT testing intervals
The following table is based on Table 1 in the IET Code of Practice. These are suggested initial intervals. Adjust based on your own data.
Office and shop environments
| Equipment type | User check | Formal visual inspection | Combined inspection and test |
|---|---|---|---|
| Stationary equipment (e.g., desktop PCs, printers, fridges) | No | 24 months | 48 months |
| IT equipment (e.g., monitors, routers) | No | 24 months | 48 months |
| Movable equipment (e.g., portable heaters, fans) | No | 24 months | 48 months |
| Portable equipment (e.g., kettles, desk lamps) | No | 24 months | 48 months |
| Handheld equipment (e.g., hair dryers in a salon) | Yes, daily/weekly | 12 months | 24 months |
| Cables and extension leads | Yes, before each use | 24 months | 48 months |
Industrial and high-use environments
| Equipment type | User check | Formal visual inspection | Combined inspection and test |
|---|---|---|---|
| Stationary equipment | No | 12 months | 24 months |
| IT equipment | No | 12 months | 24 months |
| Movable equipment | Yes, weekly | 12 months | 24 months |
| Portable equipment | Yes, weekly | 6 months | 12 months |
| Handheld equipment | Yes, daily | 6 months | 12 months |
| Cables and extension leads | Yes, before each use | 6 months | 12 months |
Construction sites
| Equipment type | User check | Formal visual inspection | Combined inspection and test |
|---|---|---|---|
| All 230V portable equipment | Yes, daily | 1 month | 3 months |
| All 110V portable equipment | Yes, weekly | 3 months | 6 months |
| Extension leads (230V) | Yes, daily | 1 month | 3 months |
| Extension leads (110V) | Yes, weekly | 3 months | 6 months |
| Site fixed equipment (e.g., cement mixers) | Yes, weekly | 1 month | 3 months |
Schools, hotels, and public venues
Equipment in environments with public access — schools, hotels, village halls, churches — generally follows the same intervals as offices, with one adjustment: portable and handheld equipment used by multiple people should be tested more frequently. The IET Code of Practice suggests formal visual inspection every 12 months and combined inspection and test every 24 months for these items.
Environmental factors that shorten intervals
The tables above are starting points. Several environmental factors mean you should test more often:
- Dust and debris — Workshops, bakeries, woodworking shops. Dust gets into ventilation slots and can cause overheating.
- Moisture — Commercial kitchens, laundries, outdoor use. Water and electricity are a well-documented problem.
- Heat — Equipment near ovens, boilers, or in server rooms. Heat degrades cable insulation faster.
- Vibration — Factory floors, construction environments. Vibration loosens internal connections.
- Public access — Equipment used by the general public gets rougher treatment than staff-only equipment.
- Cable strain — Equipment that gets moved frequently (vacuum cleaners, extension leads) suffers more cable damage than equipment that stays put.
If any of these apply, consider halving the standard interval as your starting position and adjusting from there.
How to adjust frequency based on failure rates
This is the part most businesses skip, and it's the most valuable.
After your first round of testing, look at the failure rate. The IET Code of Practice suggests:
- Failure rate below 5% — Your testing interval is probably about right. You could consider extending it slightly.
- Failure rate above 10% — Your testing interval is too long. Shorten it.
- Failure rate approaching 0% — Your interval may be too short. You're spending time and money testing equipment that consistently passes. Consider extending the interval for that category.
Track this over multiple test cycles. If your office kettles fail at 2% over three years of annual testing, switching to 24-month testing is reasonable. If your workshop power tools fail at 15% on annual testing, move to 6-monthly.
This is one reason why recording actual test values — not just pass/fail — on your PAT testing records matters. A downward trend in insulation resistance across several test cycles tells you an appliance is heading toward failure, even if it's still passing today.
Using a frequency calculator
Working out the right intervals for a mixed inventory of equipment across different environments gets complicated quickly. Our PAT testing frequency calculator takes your equipment types and environment details and gives you a recommended schedule based on the IET Code of Practice tables.
It won't replace your own judgement — you still need to adjust based on actual failure data — but it gives you a defensible starting point that you can hand to an auditor.
Keep it simple, keep it documented
The goal isn't to test everything as often as possible. It's to test at intervals that catch problems before they become dangerous, without wasting time on equipment that doesn't need it yet.
Document your rationale. If an auditor asks why you test office monitors every 48 months instead of annually, you should be able to point to the IET Code of Practice Table 1, your own failure rate data, and a written risk assessment. That's a far stronger position than "we test everything annually because that's what the contractor told us."
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