Monitoring cable laying specifications: separation of strong and weak electricity and anti-interference

Release time：2026-07-20 00:00 Views：341 author：Xinlaida Security Technology Department source：technical knowledge
Explain the requirements for spacing between strong and weak electricity, methods for bridges and pipelines, grounding and shielding treatments, to reduce interference and subsequent hidden dangers from the source.

Why we need to separate strong and weak electricity

There is an alternating electromagnetic field around the AC power cord. When laid parallel to the network cable over a long distance, interference signals will be induced in the network cable. This can range from horizontal stripes and snowflakes appearing on the screen to severe network packet loss and device disconnection. This kind of problem is extremely difficult to troubleshoot later. Must be avoided during the construction phase.

Spacing requirements

SituationMinimum Spacing
The network cable is parallel to the ordinary power cord (unshielded)≥ 30cm
The network cable should be parallel to the 220V power cord (shielded or metal tube)≥ 15cm
Network cables and high-power cables (such as elevators, air-conditioning power lines)≥50cm, the same pipe is strictly prohibited
When crossing is necessarycross vertically and avoid parallelism

Cable and pipeline practices

  • Strong and weak currentslay in separate slots; metal partitions must be installed when using bridges.
  • Metal bridges and metal conduits must be connected throughout and reliably grounded in order to function as a shield.
  • The cable filling rate should not exceed 40% (power) and 50% (communication) of the cross-sectional area of the bridge to avoid poor heat dissipation.
  • The turning radius should not be less than 6 to 8 times the outer diameter of the cable to avoid damaging the twist length of the wire pairs.
  • Outdoor buried pipes must have slopes and hand holes to prevent water accumulation.

Supplementary measures against interference

  • Use shielded network cable (STP) in environments with strong interference, and the shielding layers at both ends must be grounded (the effect of connecting only one end is limited).
  • The camera is equipotentially connected to the bracket and pole.
  • For long distances, optical fiber is preferred, which is fundamentally immune to electromagnetic interference.
  • Prevent network cables from being close to inverters, motors, and transformers.
  • Switches and equipment power supplies must have good protective grounds.

Construction Management

  1. Label both ends of each cable, and the label content is consistent with the point table.
  2. Keep the as-built drawings and location ledgers (including cable directions, lengths, and numbers).
  3. After the laying is completed, use a network cable tester to verify each cable. Do not wait until debugging to discover the broken core.
  4. Take photos at intersections of strong and weak currents and keep them on file to facilitate later investigation.

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