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Common sense about cable shield grounding
1. When the cable has only a single layer of shielding, one end of the shielding layer should be grounded at equal potential.
2. When the cable is double-insulated and shielded, both ends of the outermost shield are grounded, and one end of the inner shield is grounded at equal potential.
3. When the cable is used in places with serious interference, frequent rodent infestations, and places with lightning protection and explosion-proof requirements, armored twisted-pair shielded cables should be used (Patent No.: 2010 2 0559128.9 Beware of counterfeiting)— —ASTP-120Ω (for RS485 & CAN) one pair 18 AWG, the outer diameter of the cable is about 12.3mm. When in use, both ends of the armor layer should be grounded, and one end of the innermost shield should be grounded!
The ground resistance should not be greater than 4Ω!
"GB 50217-2007 Cable Design Specifications" also has similar statements.