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Question: 

  • I can only measure the loop impedance between L and N, but no longer between L and PE. What can be the reason?

Answer: 

You have probably accidentally activated the mode for testing in IT systems (also called IT network).
In this system the PE is not connected to the power supply, so a loop impedance measurement cannot be performed.
To switch back to normal test mode, please follow the steps below follows:

  • Turn off the installation tester
  • With the test instrument switched off, press and hold the F2 key on the installation tester
  • While holding down the F2 key, switch on the installation tester
  • You will now see “IT OFF” briefly in the display

 

 

 

 

 

 

 

 

 

Newer instruments have an additional option for IT mode, described on page 3 of the manual supplement.

You can recognize these newer instruments by the yellow silkscreen text next to the "up/down" and "light" keys.

  • Press the backlight key for 1 second to see the IT mode status
  • Use the Up/Down arrow key to toggle the IT mode On or Off

  

You should now be able to switch between L-N and L-PE again when measuring the loop impedance (with and without RCD)

Keywords: 1662, 1663, 1664FC, loop impedance,