How many square millimeters should the ground wire be for a network server rack

A typical grounding wire for a network server rack is 6 AWG copper, which equals approximately 13. 3 mm².

NEC Guidelines

The National Electrical Code (NEC) Table 250. 122 specifies the minimum size of equipment grounding conductors (EGCs) based on the rating of the overcurrent protection device (OCPD) protecting the circuit. For most server racks, which are often protected by 30–60 A breakers, the NEC recommends a 10 AWG to 6 AWG copper conductor.

Using a larger conductor is acceptable and can improve mechanical strength and reduce voltage drop.

Conversion to Square Millimeters6 AW

G copper ≈ 13. 3 mm²8 AWG copper ≈ 8. 4 mm²10 AWG copper ≈ 5.

3 mm² For aluminum conductors, a larger size is required due to lower conductivity. For example, 6 AWG aluminum is roughly equivalent to 13. 3 mm² copper, but aluminum may require 4 AWG to achieve the same fault current capacity.

Practical Recommendations

Use copper for critical server racks due to higher conductivity and reliability. Install the grounding wire in the same raceway or cable bundle as the power conductors to minimize impedance. Consider mechanical protection: a slightly larger conductor (e.g., 4 AWG / 21 mm²) can provide extra durability in high-traffic data centers.

Verify local codes: some jurisdictions may require larger grounding conductors for IT equipment or high-density racks.

Summary

For a standard network server rack protected by a 30–60 A breaker, a 6 AWG copper grounding wire (≈13. 3 mm²) is typically sufficient according to NEC Table 250. 122.

Larger sizes can be used for added safety or mechanical strength, and aluminum conductors require a larger cross-section to match copper performance.