1. Grounding treatment (mandatory requirement)
Grounding principle of armored cables
Power cable : The steel armor layer needs to be grounded at both ends to reduce the
grounding resistance and ensure that the fault current triggers the protection device to
operate .
Control/signal cable : Single-end grounding (power supply side) to avoid electromagnetic
interference loop .
Explosion-proof area : The armor layer must be connected to the equipment housing
through a dedicated grounding wire, and indirect grounding is prohibited .
About armored cables grounding operation
After stripping the sheath, weld the armor layer with copper braid or clamp it with a
constant force spring, and the grounding resistance is ≤10Ω.
The grounding wire needs to be wrapped with insulating tape and filled with sealant to
prevent moisture .
2. Stripping and jointing process
Armor layer processing of armored cables
Steel belt armor: Cut the steel belt in a circular sawing manner to 2/3 of the depth, file the
burrs after tearing off, and double clamp the bare copper wire (spacing 15mm) .
Steel wire armor: After the metal wire is wrapped, the wire is crimped and twisted, and the
insulating tape is wrapped to prevent loosening .
It is strictly forbidden to damage the internal insulation layer. The semi-conductive layer
needs to be chamfered and smoothly transitioned after stripping .
Cold shrink joint sealing
The cold shrink tube and the support sleeve overlap 20-30mm, and the support strip needs
to be pulled out counterclockwise at a uniform speed .
After the terminal is crimped, fill the sealant, cover the insulating tape, and the two ends of
the sleeve are tightly fitted with the outer sheath.
3. Adaptation to the laying environment
Direct burial laying
Armored cables must be used, with a burial depth of ≥0.7m (≥1m for farmland), 100mm
fine sand/soft soil at the bottom of the ditch, and covered with concrete guard plates.
When crossing the road/pipeline crossing, wear a protective tube (inner diameter ≥1.5
times the outer diameter of the cable).
Vertical laying in the shaft
Steel wire armor (such as YJV42) is preferred, and the tensile strength must match the
dead weight of the cable.
Fixed spacing ≤1m (horizontal) or ≤6m (vertical), bending radius ≥20 times the outer
diameter (single-core cable) .
4. Protection in special scenarios
High humidity environment: Use stainless steel armored or XLPE insulated cables, and use
double-layer waterproof sealant to treat the joints.
Explosion-proof area: Use explosion-proof joints, tighten the nuts and check the torque, and
the seals are evenly compressed.
Chemical corrosion area: Apply anti-corrosion coating to the armor layer, or add flame-
retardant PVC outer sheath.
5. Safety taboos
Insufficient bending radius: The armor has high hardness, and insufficient bending radius
can easily cause the metal layer to deform and pierce the insulation.
Dissipation neglect: Temperature needs to be monitored when densely laid, and the armor
layer may hinder heat dissipation .
No pipe protection: When crossing the road, in mechanical pressure areas or in scenarios
requiring lightning protection, armored cables still need to be protected by steel pipes.
Summary: Reliable grounding and standardized sealing are the core of safety. The laying
environment determines the type of armor (steel belt for direct burial/steel wire for vertical
shaft), and the acceptance is strictly in accordance with GB/T 12706 and GB 50257
standards.
