The technical team at Megger answer another common contractor query.
You ask: I’ve just bought a new Megger MFT1741 multifunction installation tester and it’s saving me a lot of time and trouble, but there’s one thing that puzzles me: why does it have a 100V insulation test range? When would I ever need to test insulation at such a low voltage?
Megger says: There are several instances where the 100V insulation test is useful. It’s good for pre-testing a circuit when you’re unsure about its condition or when you aren’t certain that all vulnerable equipment has been disconnected. In these circumstances, the low voltage test minimises the risk of causing damage and, if it shows everything is in order, you can be much more confident about going on to test at a higher voltage. The 100V test is also the right choice when you’re working with equipment or cables that have a normal working voltage between 24V and 50V. These shouldn’t be tested at a higher voltage unless the manufacturer specifically states that it’s OK to do so. Then there are some items of equipment where the manufacturer specifies that the insulation test voltage must not exceed 100V. Finally the 100V test is frequently needed when you’re working on data and telecomm cables and equipment. So, as you can see, that 100V insulation test is actually a very useful option to have available!
View a Megger MFT1741 data sheet by clicking here