What to look for in a portable appliance tester

When you start looking for a portable appliance tester, the first thing you will notice is the large range you have to choose from. The following is a guide to the different types, and highlights features to look for.

A simple Go/No Go tester - If you are looking to comply with the statutory regulations and test the repair work you carry out yourself - for example, extensions leads, drills, appliances - then a simple Go/ No Go Portable Appliance Tester that measures insulation and earth continuity is quite suitable.

Selectable current: The IEE Code of Practice states that the earth lead of the appliance can be tested either: a. with a current between 20-200mA while flexing the lead of the appliance or, b. a current not less than 1.5 times the rating current of the appliance, and no greater than 25 amps.

Not all Go/No Go Portable Appliance Testers are capable of testing earth leads at the larger currents, and which tester you choose largely depends on the type of appliances you come into contact with. If the earth lead on an appliance is susceptible to corrosion such as those found in a fridge, washing machine, kettle or dryer then you should test these appliances with the higher earth current to ensure any potential corroded earth wires are suitably stressed.

For testing large amounts of equipment in the workplace a testers that automates the process and has recording capabilities is more suitable.

Ensure it has the following "must have" features.

Multiple Earth Paths ability: It is important to choose a PAT tester with the ability to make accurate earth bond measurements, even when multiple earth paths exist. Most Portable Appliance Testers can measure earth leakage over multiple earth paths, but this is not the same as checking the integrity of an appliance's main earth. For example, consider the common office computer, which often has several other devices attached to it via a screened data cable - for example a printer, monitor or scanner. An earth return path can still exist even if the earth bond wire in the cord of a computer is faulty. If you buy a Portable Appliance Tester that does not automatically cater for earth bond measurement under Multiple Earth Path conditions, the only way to ensure you are actually testing the earth bond of the computer is to disconnect it from all other ancillary equipment. The end result is an increase in test time, and a significant reduction in the number of tests you can do in a day.

Upgrade: Can the Portable Appliance Tester can be upgraded and most importantly, how? Ideally you want a Portable Appliance Tester you can software upgrade.

On-board help: Portable Appliance Testers can be complicated instruments and there is nothing worse than having to hunt for that ever-elusive manual. A Portable Appliance Tester with on-board help that walks you through the tests and displays on-screen connection diagrams when you need them is a definite advantage.

View completed test results: Ensure the Portable Appliance Tester lets you go back and view the complete test results immediately after the test.

Multiple Voltage Insulation Testing:With the advent of the EMC regulations in Europe, an increasing number of appliances have used filters to manage conducted emission problems. These surge filters can cause inconsistent test results with PAT testers that use a 500V insulation test. Buy a PAT tester with the option of a 240/250V insulation test.

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