PAT450 portable appliance tester
Store up to 10 000 results
Interruption-free testing for improved efficiency with a large QWERTY keypad for fast data entry
Selectable PASS/FAIL limits
Provides an instant indication of a faulty asset
200 mA, 10 A, and 25 A bond testing
With high duty cycle for repetitive testing to verify the integrity of exposed metal work on grounded appliances and where sensitive electronics may be damaged by high currents
About the product
Easy to use, light to carry, and featuring a convenient internal database for results storage, the PAT450 portable appliance tester is optimised for use by service organisations and equipment rental companies. Key benefits of the instrument include rapid start-up, instant restart after temporary disconnection when moving between test locations, and optional barcode support to aid in rapid asset identification.
These instruments offer both manual and automatic operation. When used in automatic mode, the test structure can readily be configured to suit specific requirements. This way, for example, a supervisor can predefine a test structure for a particular application and then be sure that all tests are performed exactly as required, irrespective of who carries out the testing work.
The efficient handling of test results is another important characteristic of these innovative instruments. They have an integral multi-user database with ten times the capacity of a typical downloading PAT tester. They use a flat data structure that enhances traceability and makes it easy to set up assets and find their associated data. Results can also be stored in test groups, and there is no limit to the length of the group names. These can be made descriptive and easy to understand, which is an important aid to testing efficiency.
Tests offered by the PAT450 include earth continuity (bond testing), 250 V and 500 V insulation tests, alternative leakage tests, VA, anti-surge leads and power cords, testing 120 V assets, bond testing carried out at 10 A and 25 A as well as at 200 mA, plus 1.5 kV and 3 kV flash test functions.
The PAT450 also has a large bright colour screen for clear test results and simple menu navigation. The menus have been simplified to make operation faster and more intuitive. Five soft keys give direct access to frequently used functions, making navigation through the menus even quicker and the tester even more productive, offering a greater return on investment.
Megger’s standard issue of these instruments includes a calibration certificate, printed quick start guide, complete user guide on CD, continuity/earth bond lead and probe, and a 13 A extension lead adapter, all presented in a convenient carrying case with an integral lead/document pouch.
Product documentsAdditional documentation can be found on the support tab
FAQ / Frequently Asked Questions
Portable appliance testing is the visual examination and electrical testing of portable electrical equipment used in industrial, commercial, or public access areas and locations (including rented property) to ensure they are safe to use and cannot present an electrical hazard to the operator or anyone in their vicinity.
Barcodes can indeed save you much time on repeat testing of assets. You will, of course, need a PAT tester like the PAT450, which offers barcode support. You’ll also need to buy a barcode scanner and a label printer, but these aren’t expensive items, and if you do a lot of PAT testing, they’ll quickly pay for themselves. When you have the kit together, you can print pass/fail labels, including a barcode that identifies the asset and the type of tests carried out. Then, when you next need to test that asset, you simply scan the barcode, and this information is instantly loaded into the PAT tester. That’s a lot faster and easier than entering the information manually. And, as it happens, this setup could also solve your second problem. The label printers used with the latest Megger PAT testers print on self-laminating tape, meaning it’s virtually impossible to scribble on them or otherwise deface the labels they produce.
You’ll need a tester that helps you make the best use of your time. Rapid start-up is important, as is instant restart after temporary disconnection when moving between locations. Barcode support can also be helpful, as it provides a quick way of identifying assets. Depending on how you work and the type of assets you’ll be testing, an option for automatic testing with a user-defined test structure can be another huge time saver. For testing large numbers of assets, you’ll also need a tester that can store many results in its internal memory, like the PAT450, which can hold up to 10 000 results. There should also be facilities for organising the stored results so that you can find them easily. A QWERTY keyboard is essential for fast data entry. Finally, make sure the tester has all the features you need.
The frequency of the visual examinations and electrical tests is established by risk assessment and experience.
No strict test schedules exist. However, a simple risk assessment will identify the suitability of an asset for the application and environment in which it is being used and whether a change to the suggested retest frequency or even removal of the equipment altogether is appropriate. Criteria that may influence the decision include:
- Location of the equipment
- Equipment type and class of construction
- Frequency of use
- Competence of user
- The installation method
- Previous records
- Whether the equipment is on hire
You should regularly review the frequency of visual examinations and electrical tests. You must pay particular attention to initial inspections and electrical tests to determine whether the frequency or equipment type needs to be changed.
Visual examination is vital and always precedes electrical testing. It often reveals major defects that testing alone would not show. Effective hierarchical progression of in-service visual examination and/or electrical testing categories include:
- Operator checks (no records if the equipment is OK).
- Formal visual inspection (recorded).
- Combined visual examination and electrical testing (recorded)
Various people have responsibilities for electrical equipment, these being:
- Property owners, equipment owners, company owners, directors, and line managers
- The person undertaking the formal visual examination and electrical testing
- Maintenance managers
- Operators of the equipment – to monitor the equipment they use and ensure it has no obvious faults or damage
Further reading and webinars
You can use an adaptor (p/n 35871). Set the port number in the properties of Download Manager to the same port number in Device Manager to ensure the software is looking at the correct port.
The battery may not have enough charge. Try leaving the PAT plugged in for a couple of hours to charge or replace the 9 V rechargeable PP3 battery. Be sure to press the red button when finished testing to prevent the battery from draining.
Hold down the test button while the tester switches on and select reset. Warning: Back up your data before resetting, as data may be deleted in the process.
Although infrequently encountered, when an “E56” message appears, a fuse has blown due to a failure on the programmed board. You can replace fuses and restore operation for a time, but most likely, there is a problem (defective or burnt-out component) on the board. Schedule your PAT450 for calibration or replacement.
Interpreting test results
Earth continuity is applicable for Class I equipment and extension leads. The purpose of the test is to ensure that the earth terminal has a low resistance connection to the conductive metal casing of the appliance by electrical bonding. Two test methods are available, and the technique used should depend on the circumstances.
- Low current continuity test - A continuity measurement is made with the asset plugged into the PAT tester and using a short circuit test current of between 20 and 200 mA. The test is made between exposed conductive parts of the equipment and the earth pin of the plug (or earth-terminal of the supply). This is performed using the PAT’s earth bond lead. Note the maximum resistance value while flexing the asset supply cable. You should investigate any fluctuation in the reading. You should also visually examine the power cable terminations at both ends.
- High current bond test - A continuity measurement is made with the asset plugged into the PAT tester and using a test current of at least 1.5 times the fuse rating (max 26 A) for between 5 to 20 seconds. The bond test should be made between exposed earthed conductive parts of the equipment and the earth pin of the plug (or earth-terminal of the supply). This is done by connecting the earth bond lead of the PAT to the exposed metalwork. Note the maximum resistance value while flexing the asset supply cable. You should investigate any fluctuation in the reading. You should also visually examine the power cable terminations at both ends.
Take care when measuring earth bond on appliances where the construction includes exposed metalwork having casual contact to earth. This metalwork is primarily protected by double or reinforced insulation. The earth connection is only classed as ‘fortuitous.’ So the resistance value is unlikely to be as low as truly bonded metalwork, and a test performed on this unbonded metalwork may give misleading results. Examples of this construction may include a steam iron’s soleplate or a kettle’s metal chassis. A high current bond test using up to 26 A may also damage casual-contact components. You should perform a low-current test first to identify potential problems.
To pass the earth continuity test, the measured value should not exceed those shown:
|For appliances without a supply cord
|For appliances with a power cord (3 core), extension leads, multiway and RCD adaptors
|(0.1 + R) Ω where R is the resistance of the protective conductor of the supply cable
If the resistance R of the protective conductor cannot easily be measured, the table below provides nominal cable resistances per metre length for various types of flexible cable.
You should identify the cable and measure its length. You can calculate the protective conductor resistance using the app PAT toolbox or by using the table and a calculator. The Megger PAT400 testers have built-in compensation for resistance in long supply cables.
|Nominal conductor CSA (mm2)
|Typical no. of strands in conductor
|Maximum current carrying capacity (A)
|Nominal conductor resistance (Ω/m)
Generally, you perform insulation testing by applying a known (500 V DC) test voltage and measuring the insulation's resistance. 500 V may cause damage to sensitive equipment such as IT. Therefore, you may substitute with a low voltage (250 V) insulation test, a touch current test, or an alternative leakage current test.
Note: you should not touch appliances during an insulation test. The exposed metalwork may rise to the test voltage if a fault exists.
The test method varies depending on whether the appliance is Class I or Class II. For a Class I test, the appliance is plugged into the PAT tester, and the insulation test is carried out between the earth pin and the plug's combined live and neutral pins. The Megger PAT makes these connections for you.
A Class II appliance is slightly different as there is no connection to the plug earth pin. This time a connection is made between the combined live and neutral pins and any metal parts, dirty or conductive areas of the casing, and may involve several tests. The connection method is the same as that used for the earth bond test, using a test probe.
Note: You must switch on the appliance at its own power switch for both test methods. If it is not, then the electrical test is only being carried out as far as the switch. The minimum insulation readings that you should obtain are shown in the table below. For equipment with an electrically operated switch, the insulation test can be substituted with a mains-powered protective conductor or touch current measurement.
This test is an alternative to an insulation test. We recommend its use when an insulation test could damage the asset or when the insulation test results are suspect. For this test, you energise the asset at its normal operating voltage, and any current flowing to earth is measured. For Class I, this is to the earth pin of the plug; for Class II, this is to any accessible conductive surface using a remote probe.
Note: a low voltage insulation test should be performed before any energised test, such as the touch current test, to identify any potential danger from poor insulation and shorted connections. This test is only available on the more sophisticated portable appliance testers, such as the Megger PAT.
It is essential to ensure that the asset is safe to run during the test. For example, if testing a kettle, it should be part-filled with water so as not to damage the element during this test.
This test is useful where it may be deemed dangerous to run the asset during a protective conductor or touch current measurement. This test uses 40 V AC, which will not operate the asset during the test. This test can be battery powered, removing the need for a mains supply during testing.
In all cases, the current is measured within five seconds after the application of the test voltage; the values must not exceed those given below.
|Portable or handheld Class I
|Class I heating equipment with a rating >= 3 kW
|All other Class I equipment
|Class II equipment
|Class III equipment
|Touch current (max.)
|0.75 mA or 0.75 mA per kW whichever is the greater with a maximum of 5 mA
A functional test is carried out during the “load” test or the mains-powered protective conductor or touch current measurement. This test will determine the following:
- if the asset functions correctly
- the VA rating of the appliance
This can be a good indicator of future problems and potential failures in an appliance. Problems, like worn bearings on a drill, would probably result in increased current drawn from the supply and, therefore, an increase in the VA reading.
User guides and documents
Software and firmware updates
Firmware for PAT300 and 400 series
The PAT300/400 Series portable appliance testers are firmware upgradeable via a Windows PC with a USB interface. Firmware updates are developed and released to add additional functionality to your PAT300/400 Series tester.
- Install PAT upgrader driver software BEFORE connecting your PAT300/400 Series tester to your computer via the USB interface.
- Each PAT400 zip file contains multiple language versions with applicable test groups, please use the correct file corresponding to your region.
- Please follow PAT upgrader instructions accompanying the upgrader software. Latest PAT300/400 firmware version 2.50. If using in conjunction with PowerSuite software, an upgrade may be required in order to provide compatibility with the latest firmware.
- DO NOT INSTALL FIRMWARE VERSION 2.50 IF YOUR CURRENT FIRMWARE VERSION IS BELOW 2.10.
- Latest firmware version: 2.50 - Released 2014
FAQ / Frequently Asked Questions
Microwave ovens should not show any sign of damage, distortion, or corrosion. Those that do should be withdrawn from service. They require specialist expertise to repair or service. They need an additional functional test to check that the door interlock interrupts the power supply satisfactorily.
There is no requirement to label any equipment that requires visual examination and electrical testing. Still, indicating that the asset has been tested satisfactorily is helpful. The label should consist of a unique identifier for the equipment and an indication of its state.
A failed asset should have clear identification that it has failed.
Labels should adhere to a mixture of surfaces to which they will be applied. They should be durable and able to last until the asset is re-tested. Labels may either be filled in by hand or printed. Printed labels often have a barcode for the identifier, making them readable with a suitable barcode scanner.
This can be a great time saver with a portable appliance tester that supports it, such as the PAT400.
Printed labels should be of the ‘Thermal transfer’ type, not the ‘Direct thermal’ type as it fades quickly.
Megger designs its portable appliance testers to test equipment supplied by plug and socket connection. Testing is done simply by unplugging the equipment and plugging it into a Megger PAT tester. One method for testing assets connected to fused spurs is to temporarily connect the asset to a 13 A plug and test conventionally using the PAT tester.
Electrical testing consists of the following in this specific order:
- Earth continuity or bond tests
- Insulation resistance testing (if a 500 V insulation test is not appropriate, you can substitute with a 250 V insulation test, a touch-current test, or an alternative leakage-current test)
- Functional checks
Some test equipment can perform tests that could damage an appliance they are used on in certain circumstances. Flash testing (also known as hi-pot or dielectric strength testing) is one such test. It is customarily carried out by manufacturers or when an appliance has undergone a deep overhaul.
Have you applied lead compensation? This allowance factors in the extra resistance that long extension leads add. The PAT400 can calculate this for you.
No. It meets strict safety requirements specific to electrical test equipment and is used by competent persons with training in electrical safety.