In the wiring for IEC 61000-4-4, the height of the power line between the test generator and the EUT is specified as 10 cm. How should the height between the primary side and the test generator be considered when arranging the setup?

In the wiring for IEC 61000-4-4, the height of the power line between the test generator and the EUT is specified as 10 cm. How should the height between the primary side and the test generator be considered when arranging the setup?

Although it is not explicitly specified in the standard, we recommend arranging the primary side to test generator section at a height of 10 cm as well, and the cable length must also be defined so that it is the same each time.
[Reason]
In common-mode tests such as the fast transient/burst test, noise is injected into each line with reference to the ground plane. The loop of the noise current is determined by the parasitic capacitance with the ground plane, including the EUT, so the distance (height) between each cable and the ground plane is important.
When cables are arranged, vertical sagging may occur, and this can cause differences in the test results. For example, if 5 mm of sag occurs when the specified height is 1 cm, and 5 mm of sag occurs when the specified height is 10 cm, the latter results in relatively less variation in parasitic capacitance and better test reproducibility. For this reason, a height of 10 cm is recommended.