Grounding System Design Using Bimetallic Conductors
RAYTRON Technical Team1
1RAYTRON Group, China
发布日期: March 2026版本: 1.0
DOI:10.1000/raytron.WP-07-03
1. Introduction
1.1 Grounding Importance
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Figure fig1 Figure 1: Grounding system functions and components
Function
Purpose
Safety
Protect personnel
Equipment protection
Limit damage
Lightning protection
Path to earth
System reference
Voltage stability
1.2 Why Bimetallic for Grounding
Material
Conductivity
Cost
Theft Risk
Cu
High
High
High
CCS
Adequate
Low
Low
Galvanized steel
Low
Low
Low
2. Grounding System Functions
2.1 Safety Grounding
Requirement
Standard
Step voltage
IEEE 80 limits
Touch voltage
IEEE 80 limits
Ground potential rise
Per system design
2.2 Fault Current Path
Parameter
Requirement
Impedance
Low enough for fault clearing
Current capacity
Withstand fault energy
Reliability
Continuous path
2.3 Lightning Protection
Component
Function
Air terminals
Intercept lightning
Down conductors
Conduct to ground
Ground electrodes
Dissipate to earth
3. Material Selection
3.1 Conductor Options
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Figure fig2 Figure 2: Grounding conductor material comparison
Material
Conductivity
Ampacity
Corrosion
Theft
Copper
100%
High
Moderate
High risk
CCS-21%
21%
Adequate
Good
Low risk
CCS-30%
30%
Better
Good
Low risk
Galvanized steel
8%
Low
Good
Low risk
3.2 Selection Criteria
Application
Recommended
High fault current
Cu or CCS-30%
Theft-prone area
CCS
Cost-sensitive
CCS
High-corrosion
CCS or Cu
3.3 Equivalent Sizing
For equivalent ampacity:
Cu Size
CCS-21% Equivalent
4/0
500 kcmil CCS
2/0
350 kcmil CCS
2 AWG
4/0 CCS
4. Design Calculations
4.1 Ground Resistance
Typical targets:
Installation
Target Rg
Substation
<1 Ω
Transmission tower
10-25 Ω
Industrial
5 Ω
4.2 Fault Current Capacity
4.3 Step and Touch Voltage
Must be within limits:
Condition
Limit Formula
Step voltage
Per IEEE 80
Touch voltage
Per IEEE 80
5. Installation Guidelines
5.1 Conductor Installation
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Video 1: CCS grounding conductor installation procedures
Practice
CCS Guideline
Burial depth
Per code (typically 0.5-0.8m)
Connections
Exothermic preferred
Routing
Avoid sharp bends
Protection
Conduit at crossings
5.2 Connection Methods
Method
CCS Application
Exothermic weld
Preferred
Mechanical clamp
Acceptable
Crimp
Use correct dies
5.3 Electrode Installation
Type
Installation
Ground rod
Drive to depth
Ground plate
Bury horizontal
Ground grid
Mesh of conductors
6. Maintenance
6.1 Inspection
Activity
Frequency
Visual inspection
Annually
Resistance test
Every 3-5 years
Connection inspection
Annually
6.2 Testing
Test
Method
Ground resistance
Fall-of-potential
Continuity
Point-to-point
Current distribution
Clamp-on
6.3 Repair
Issue
Repair Method
Broken conductor
Exothermic splice
Corroded connection
Replace/clean
High resistance
Add electrodes
7. Conclusion
7.1 Summary
Advantage
CCS Grounding
Cost
50-70% savings vs Cu
Theft deterrence
Excellent
Performance
Adequate
Service life
30+ years
7.2 Recommendation
CCS is recommended for most grounding applications where:
Theft is a concern
Cost optimization needed
Standard fault current capacity adequate
8. References
IEEE 80. (2013). Guide for Safety in AC Substation Grounding.
IEEE 837. (2014). Qualifying Permanent Connections.
FAQ
How does CCS compare to copper for fault current capacity?
CCS-21% has approximately 21% IACS conductivity versus 100% for copper. For equivalent fault current capacity, CCS conductors need to be sized larger (e.g., 4/0 Cu equivalent requires 500 kcmil CCS).
What is the service life of CCS grounding systems?
CCS grounding conductors have a service life of 30+ years when properly installed, with the copper cladding providing corrosion protection similar to solid copper in most soil conditions.
Can CCS be used for substation grounding grids?
Yes, CCS is suitable for substation grounding grids. Size appropriately for fault current capacity and verify that ground resistance meets IEEE 80 requirements for step and touch voltage limits.
What connection methods work best for CCS?
Exothermic welding is the preferred method for underground CCS connections, providing a permanent, low-resistance joint. Mechanical clamps and compression fittings rated for CCS are acceptable for accessible locations.
