CISPR 25:2021 6.4.3 Test procedure ... The current probe shall be mounted around the complete harness (including all wires). If the EUT has multiple connectors on the unit resulting in multiple wire bundles, the test plan shall define which wires shall be included in the probe for measurement. In the absence of any definition, measurements shall be made for each bundle (connector) separately as well as combined (i.e. all together).
CISPR 25:2021 6.4.2.2 Location of the test harness: …. The test harness wires shall be nominally parallel and adjacent unless otherwise defined in the test plan.
We normally want to capture noise from wire-to-wire coupling, that’s why all wiring must run parallel and adjacent along the test harness except for the portion of wire/connector with CE-I probe clamped on it. Scenario #1 below shows the correct test harness and wiring layout.
Scenario #2 is incorrect since CISPR 25 require "parallel and adjacent" wiring. CISPR 25 does not define a minimum or maximum distance between the wires included in the test harness.
Christian Rosu