There is strong current interference outside, and single-point grounding cannot meet the fastest discharge of static electricity.
If the cross-sectional area of the grounding wire is large and can ensure the fastest discharge of static electricity, it should also be grounded at a single point. Of course, if that’s the case, there’s no need to opt for two layers of shielding.
Otherwise, two layers of shielding are necessary. The outer shielding is mainly to reduce the interference intensity, not to eliminate the interference. At this time, it must be grounded at multiple points. Although it cannot be put out, it must be weakened as soon as possible. To weaken it, multi-point grounding is the best choice.
For example, the cable tray in the enterprise is actually the outer shielding layer, which must be grounded at multiple points. The first line of defense is to reduce the intensity of the interference source.
The inner shielding layer (in fact, you will not buy double-layer cables, generally the outer layer is the cable tray, and the inner layer is the shielding layer of the shielded cable) must be grounded at a single point, because the external strength has been reduced, discharge as soon as possible to eliminate interference That’s the inner purpose.