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How Often Does A PAT Tester Need To Be Calibrated?

Like any other testing tool or device, PAT testers don’t stay accurate forever. For various reasons like falls, water damage or electrical faults, a PAT tester can become unreliable.

This can be dangerous since it can pass a faulty appliance, and everyone continues to use it thinking it’s safe.

In this post, we discuss how often a PAT tester needs to be calibrated, who calibrates it and how to tell if your PAT tester is not working properly.

Can You Calibrate A PAT Tester Yourself

So far, I haven’t come across a PAT tester that allows self-calibration. Generally, you cannot calibrate a PAT tester yourself.

That’s because calibrating a PAT tester requires special expertise and access to specialised testing equipment. You may also need certain software to adjust a PAT tester.

If you attempt to calibrate your own tester, you could damage it and result in inaccurate test results. Also, you can’t give yourself a calibration certificate.

Here’s a behind the scenes video that shows what’s involved in testing and calibrating electrical equipment.

There are plenty of companies in the UK who provide PAT tester calibration services. You fill in a form online, send the PAT tester to them, and then get it back after a few days complete with a calibration certificate.

Some manufacturers also provide discounted calibration services. Instead of sending the PAT tester to some other company, you can send it back to the manufacturer for calibration.

Do I Have To Calibrate A New PAT Tester?

When you buy a new PAT tester, you don’t have to worry about calibration. That’s because most PAT testers come already calibrated by the manufacturer.

To verify that the PAT tester is calibrated and working properly, make sure it comes with a calibration certificate from a recognised entity.

Check whether the certificate is included before you order, otherwise you’ll have to spend more money getting the tester calibrated.

How Often Do You Need To Calibrate A PAT Tester?

There’s no legal standard on how often you need to calibrate a PAT tester. But the consensus among experts and companies is that PAT testers need to be calibrated once every 12 months.

That’s why the calibration certificate included with PAT testers expires after one year.

Of course, you can have a PAT tester calibrated sooner than that especially if you think there’s something wrong with it. For example, if it fell or got exposed to moisture, it’s a good idea to get it calibrated just to make sure it’s working right.

You may also need to get a professional calibration sooner if your PAT tester didn’t include a calibration certificate.

If you work with appliances that pose a high risk to employees, you may also want to have the PAT tester checked and calibrated more often like twice a year for added safety.

What Happens During The Calibration Process?

When you send a PAT tester in for calibration, they run a bunch of tests to check all the functions of the PAT tester.

They compare the results of these tests to standardised values to ensure the PAT tester is right on the mark or within an acceptable margin of error.

If they find that the PAT tester has drifted from the initial specs set by the manufacturer, they’ll adjust it.

Calibrating a PAT tester may also involve updating the device’s firmware as well as a visual inspection of all the components to ensure there’s nothing faulty.

How Much Does It Cost To Calibrate A PAT Tester?

PAT tester calibration can cost between £50 to £500 or more depending on several factors.

  • If your manufacturer or seller provides calibration services, they might charge less if you bought the PAT tester from them. Some sellers can even repair and calibrate it for free within the warranty period. Before you look for a third party calibration service, check with the manufacturer first – you might save some money.
  • Third party calibration services typically charge a few hundred pounds.
  • Some companies offer several tiers of service. For instance, it might cost £100 just to check if a PAT tester is working properly, and £200 to calibrate and adjust it if necessary.
  • Advanced PAT testers may cost more to calibrate compared to basic PASS/FAIL PAT testers. Before you send in your device, ask the company how much it’ll cost to calibrate your specific model.

The good news is that most PAT calibration services will provide a price quote before you send the PAT tester. This makes it easy to compare the pricing between different companies.

Is It A Legal Requirement To Calibrate A PAT Tester?

PAT testing itself is not a legal requirement. The law simply says that any electrical equipment that can be a hazard in the workplace be maintained in a safe condition.

How you do this is up to you as the employer or business owners. PAT testing is one of the most common ways to fulfil this requirement.

Since PAT testing is not a legal requirement, calibrating a PAT tester is also not a legal requirement. Companies do it to ensure their appliances and electrical equipment are safe for their employees.

In addition, PAT tester calibration can protect business owners and PAT testers from liability. If there is an incident involving electrical equipment, you can prove that it was tested with a calibrated PAT tester.

If your PAT tester’s calibration certificate had expired at the time, that could put you in trouble.

What Damages A PAT Tester?

In most cases, you don’t calibrate a PAT tester because it’s damaged. A majority of measuring instruments will over time naturally drift from the correct specifications.

They become less accurate even if you take good care of it. That’s the biggest reason why you need to get a PAT tester calibrated annually.

In some cases, though, a PAT tester can get damaged and become less accurate.

  • Impact from falling or hitting other objects can damage internal components. We recommend storing and transporting a PAT tester in a protective pouch or case.
  • Exposure to the elements or extreme temperatures can damage PAT testers. If you check your PAT tester manual, it probably has a recommended storage and usage temperature range.
  • PAT testers are also susceptible to electrical faults caused by overvoltage or overcurrent. Using the wrong batteries can also damage the tester.

Signs Of A Faulty PAT Tester

If you suspect that your PAT tester is damaged or not working properly, do not wait until the end of 12 months to have it calibrated.

Remember that one of the risks of a faulty PAT tester is that it can PASS unsafe electrical equipment. Get it calibrated immediately.

Here are some signs of a damaged or faulty PAT tester to look out for:

  • If you can see signs of external damage such as cracking or scorch marks.
  • If the PAT tester displays a reading that you don’t expect. This is only possible with one of those advanced testers that display additional readings instead of just PASS or FAIL.
  • If the PAT tester shows a different result from another calibrated PAT tester. One of the testers is wrong.
  • If you test many appliances and equipment and get the same PASS (or FAIL) result every time. You should get different results now and then. There’s a chance all those appliances are good, but get the tester calibrated for peace of mind.

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