Made 2 Measure: The Touch-Voltage Button

Made 2 Measure: The Touch-Voltage Button

The Megger team answer your questions about the range selector switches on the MFT1741

You ask:

My new MFT1741 multifunction installation tester is easy to use and very versatile, but I’ve noticed that between the range selector switches there’s a white circle with an icon that looks like a person on top of an earth symbol. What’s that all about?

We answer:

That’s the touch-voltage button! Touch voltage is the voltage that exists when there’s a higher resistance path to exposed metalwork than to another piece of exposed metalwork in close proximity, or the ground beneath the feet of a person who touches the metalwork. The Wiring Regs say that in most locations the touch voltage must not exceed 50V and that it must be less than 25V in special locations, such as swimming pools. The touch-voltage button on the MFT1741 (and on some other instruments in the MFT range) gives you a quick and easy way of checking. To use it, all you do is hold your finger on the button while you apply a single test lead to an item of exposed metalwork. If there is a significant touch voltage, the MFT will warn you. This is a great way of carrying out spot checks as you can just wander around an installation touching the probe briefly on exposed metal surfaces to look for hazardous voltages.

For more Made 2 Measure articles from Megger click here.

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