Simplified Cable Separation Formula for Data Centers

In high-density environments like data centers, proper separation between power and data cables is critical to minimize electromagnetic interference (EMI), ensuring clean data transmission and system reliability.

While detailed recommendations are available in standards such as BICSI 002, TIA-569-D, and the National Electrical Code (NEC), engineers often need a quick estimation method when planning on the fly.

Cable Separation Formula

S = k × I

Where :

• S = Separation distance (in inches or mm)
• k = Environmental constant (depends on cable type and routing method)
• I = Current in the power cables (in Amps)

Environmental Constants (k) for Practical Use

Unshielded Power Cables (Open Air)

Unshielded power cables have the highest potential to emit electromagnetic interference because there’s no shielding to contain the magnetic fields generated by current flow. Open air installations exacerbate this since there’s no containment or barrier. Hence, k=0.5 inches per Amp

Shielded Power Cables or Metal Conduits

Shielding or running cables in a metal conduit reduces the amount of EMI. The conduit acts as a Faraday cage, preventing electromagnetic fields from escaping. Hence, k=0.25 inches per Amp

High Voltage Cables (>480V)

High voltage cables inherently carry higher electromagnetic fields, increasing the risk of interference with nearby data cables. Even with shielding, higher voltages necessitate greater separation to prevent crosstalk and ensure signal integrity. Hence, k=1.0 inches per Amp

Separate Metallic Conduits

When both power and data cables are housed in separate metallic conduits, the level of EMI interference is minimal because the cables are physically shielded from each other. This setup provides optimal protection, reducing the need for large separation distances. Hence, k=0.1 inches per Amp

Reference & Reliability

These constants are not pulled from a single prescriptive code, but instead reflect industry-accepted best practices from:

• BICSI 002 (Data Center Design and Implementation Best Practices)

• TIA-569-D (Pathways and Spaces Standard)

• NEC (National Electrical Code)

These documents often specify minimum separation distances based on voltage levels, cable shielding, and pathway types, but leave room for engineer judgment based on real-world conditions.

SUMMARY

This simplified formula provides a fast and effective way to estimate EMI-safe separation distances in your design phase, especially when full standards access isn’t immediately available.

For detailed planning, always refer to BICSI or TIA standards and coordinate with local codes and site-specific engineering guidelines.

Reach out to Northern Link experts for tailored design support and standards-based cabling solutions.