What was the effect of having 120 AC @ 400 hz as opposed to 60HZ.?? Had 400Hz hum instead of 60??
In my world we have to live in an environment from shipboard (aircraft carrier is one of the worst cases) to airborne (F-whatever fighter jet), missile or drone so the environment can be way baaad from an EMI perspective. Shielding wires/cable runs is one of the methods used to survive this harsh EMI environment - just need to design it into the overall design. EMI can affect the overall data quality - so any way that you can mitigate these issues helps in getting better data to evaluate the system under test.