(1) Ground Wiring

When wiring an EMI filter with a ground wire, use a wire that is as thick and as short as possible.
A long ground wire increases inductance, which can degrade high‑frequency attenuation.

If the metal chassis of the EMI filter is connected to the customer’s enclosure, a similar effect to using a short ground wire can be obtained.

(2) Input and Output Wiring

Separate input wires from output wires.
If the input and output wires of an EMI filter are bundled together or routed close to each other, the high-frequency noise components may bypass the filter, reducing its attenuation performance.
Twisting the input wires (and/or output wires) in pairs can help reduce noise.