Portable appliance tester

It is particularly important to check that the plug top and cables of handheld electrically powered tools and extension leads are in good condition. Damaged plug tops and cables must be repaired before you use them. All electrical power tools of 110 and 230 V must be tested with a portable appliance tester (PAT) in accordance with the company s health and safety procedures, but probably at least once each year. 

In the case of portable equipment, testing is often carried out using a proprietary portable appliance tester (PAT). One useful test is the measurement of e insulation resistance to confirm that it is sufficiently high to prevent undue current leakage. Additionally, for class I equipment (that must be earthed) it is important to verify that the connection to earth is sound, i.e. its electrical resistance is low, and that the conductor is capable of carrying the sort of high current that may occur under fault conditions. Both the HSE and the lEE have produced guidance on electrical equipment maintenance. ... 

Combined inspection and testing is also necessary on some equipment because some faults cannot be seen by just looking - for example, the continuity and effectiveness of earth paths on class I equipment. For some portable appliances the earth is essential to the safe use of the equipment and, therefore, all earthed equipment and most extension leads should be periodically tested and inspected for these faults. All portable appliance test instruments (PAT Testers) will carry out two important tests earth bonding and insulation resistance. 

Earth bonding tests apply a substantial test current, typically about 25 A, down the earth pin of the plug top to an earth probe, which should be connected to any exposed metalwork on the portable appliance being tested. The PAT Tester will then calculate the resistance of the earth bond and either give an actual reading or indicate pass or fail. A satisfactory result for this test would typically be a reading of less than 0.1 n. The earth bond test is, of course, not required for double-insulated portable appliances because there will be no earthed metalwork. 

All PAT Testers are supplied with an operating manual, giving step-by-step instructions for their use and pass and fail scale readings. The HSE suggested intervals for the three levels of checking and inspection of portable appliances in offices and other low-risk environments are given in Table 1.3. 

State the two important tests that a PAT tester carries out on a portable appliance. 

The widest field of battery application both in the number of batteries and in their diversity is that of portable units and domestic appliances. Typically this involves batteries of low and medium capacity from 0.01 to 100 Ah. Battery-powered electrical units include various radio sets, tape recorders, cell phones, TV sets, audio and video players, radio transmitters for civil and military use, portable flashlights for underground and other use, miniaturized devices electronic watches, hearing aids, pocket calculators, toys, some household appliances (electric shavers, measuring instruments including testers, radiation monitoring instruments, etc.), and various medical devices (cardiac pacemakers). 

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