Guard traces on Hioki DT4256

[golfballs32]

After watching EEVblog #973 about the Hioki DT4256 multimeter, i have questions about the use of guard traces in it. At around 7:16 there are guard traces on the meter. I assume that these are the measurement traces coming from the input jack/current shunt. I have heard that guard traces do not make much of an improvement on a board with ground planes, which i presume this has.

Do the guard traces provide any serious benefit or is it just gilding the lilly?

[Siwastaja]

You are probably thinking about not needing ground fills between the traces in a 4-layer (or more) design with a closeby ground plane from AC effects viewpoint.

Guard traces like this are against DC leakage due to board surface contamination. They are often actively driven to the same voltage level as the trace being guarded. Ground fill below has nothing to do with this.