Multifunction Electrical Testers
Multifunction Testers, also known as MFT’s, are combinations of electrical testing devices that can be used to carry out various types of the 17th edition electrical testing procedures typically used in commercial, domestic and agricultural settings. They allow electricians to perform different tests in a timely and efficient way without the need to switch between equipment. They are used to test electrical circuits that use low and extra low voltages. Multifunction testers are able to perform continuity tests (or low ohms resistance tests) and insulation resistance tests (or high ohms resistance tests) and they can also perform earth fault loop impedance tests, prospective short circuit current tests and RCD tests.
Multifunction testers can vary in many ways so when choosing one make sure it suits your needs. There are many products on the market ranging widely in price. While the high-end multifunction testers have many extra functions there are a number of things to consider before actually purchasing one. The purchasing decision should be considered an investment as you should expect many years of service from it.
Confusingly, there are also multifunction testers which are not 17th edition testers. Basic multifunction testers, such as the ET4 from Martindale Electric, can accurately perform common tests for AC and DC current, voltage and electrical continuity while the ET5 can also take K-type thermometer probes making it an all in one tool for most applications. Devices like these are compact and easy to carry around; they fit in a shirt pocket, for convenient testing in most scenarios.
Furthermore remember that when it comes to electrical testing, safety is of paramount importance. There are a number of precautions that need to be taken into consideration in order to assure the safety of everyone involved. The first and most important part is to ensure that the equipment or appliance being tested is dead and it stays dead for the whole of the time the tests are in progress. There are very rare occasions where electricians are required to work with live circuits but even then all work should be done in accordance with the Electrical Safety First Best Practice Guide and within the H.S.E’s guidance using suitable protective equipment.
In areas where there are many people working, in order to ensure that the circuit stays dead during the test the use of multiple lock-off tag-off systems is recommended, with one lock off device for each worker. While a very simple and quick procedure, it will warn anyone that work is underway and may save a life or prevent serious injury.
Having locked off, the importance of proving a voltage indicator before and after testing must not be forgotten. There are a number of excellent proving units now available to ensure voltage indicators and test lamps can be fully checked prior to and after a circuit has been proved dead.
It is important that MFTs are calibrated in order to ensure that readings are accurate and potential mistakes are avoided. There are a number of calibration checkboxes, or electrical checkboxes, that are used for routine verification of test equipment and allow users to maintain accuracy between regular calibrations. However many users have a socket with known values and an appliance with known resistance values, or even a couple of resistors. Using those and getting consistent readings suggest that your tester is working properly and the readings are accurate.
These interim tests do not remove the need for a proper calibration at regular intervals. Although the interval should be based on a risk assessment, the great majority of testers are re-calibrated annually.
Most importantly whatever type of electrical testing equipment you decide on, quality and accuracy are the key factors. As you’d expect with most tools, you tend to get what you pay for. Most high quality test equipment is available through your usual electrical supply wholesaler and almost everything can be purchased online. Just beware of ‘too-good-to-be-true’ prices to obtain accurate and reliable measurements with excellent durability and after sales services choose a manufacturer you know of and ensure it’s the genuine article and not a rip off.