How to calculate copper busbar ampacity? This guide covers calculation methods, sizing charts (including 12x4mm), and comparisons with aluminum, providing datasheet for electrical system design.
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What Is Copper Busbar Ampacity?
Copper Busbar Ampacity refers to the maximum continuous current a copper busbar can safely carry under specific environmental conditions (e.g., temperature, heat dissipation, insulation level). It is determined by factors like cross-sectional area, copper purity, surface treatment, and installation methods (such as dense packing or ventilation).
How to Calculate Copper Busbar Ampacity?
Methods about how to calculate copper busbar ampacity:
1. Cross-Sectional Area Estimation (Single Busbar)
- Formula: I=W×K
- W: Busbar width (mm)
- K: Thickness factor (e.g., 18 for 10mm thickness)
2. Multi-Layer Busbar Correction
- Double-Layer: Idouble=Isingle×1.58
- Triple-Layer: Itriple=Isingle×2
3. Temperature Correction
- Lower Temperature (e.g., 25℃): Icorrected=I40×1.18
- Higher Temperature (e.g., >40℃):Icorrected=I40×0.9
4. Simplified Formula
- Formula: I=W×(T+8.5)
- W: Busbar width (mm)
- T: Busbar thickness (mm)
5. Environmental & Installation Adjustments
Parallel Busbars (AC):
- 2 bars: I×0.8
- 3 bars: I×0.7
- 4 bars: I×0.6
6. Copper vs. Aluminum Conversion
Formula: Icopper=Ialuminum×1.3
7. Practical Recommendations
- Refer to Tables: Use standards like Industrial and Civil Power Distribution Design Manual for precision.
- Safety Margin: Design with 10–20% reserve capacity.
- Temperature Monitoring: Ensure long-term temperature rise ≤70K (Class F insulation) to prevent aging.
What is the Ampacity of a 12 x 4 Copper Busbar?
For a 12×4mm copper busbar (40℃ ambient, ΔT≤50K):
- Vertical mounting: ~320A (bare copper).
- Horizontal mounting: ~280A (12% reduced heat dissipation).
Key adjustments:
- Tin-plated surface: +8% (→345A vertical).
- 60℃ ambient: Derate 30% (→~224A).
Copper Busbar Ampacity Table in MM
| Busbar Size (Width × Thickness, mm) | Ampacity(Vertical, A) | Ampacity (Horizontal, A) | Horizontal Reduction Factor |
| 15 × 3 | 165 | 145 | 0.88 |
| 20 × 5 | 290 | 255 | 0.88 |
| 30 × 4 | 400 | 360 | 0.90 |
| 40 × 5 | 540 | 485 | 0.90 |
| 50 × 6 | 740 | 665 | 0.90 |
| 60 × 6 | 900 | 800 | 0.89 |
| 80 × 8 | 1,400 | 1,260 | 0.90 |
| 100 × 10 | 2,300 | 2,050 | 0.89 |
| 120 × 12 | 2,900 | 2,600 | 0.90 |
Copper Busbar DC Ampacity Chart
| Copper Busbar Dimensions (Width × Thickness, mm) | Single-Layer Ampacity (A) | Double-Layer Ampacity (A) | Triple-Layer Ampacity (A) |
| 40 × 4 | 480 | 750 | 960 |
| 60 × 6 | 840 | 1,344 | 1,722 |
| 80 × 8 | 1,280 | 2,000 | 2,560 |
| 100 × 10 | 1,810 | 2,824 | 3,620 |
Copper vs Aluminum Busbar Ampacity
Conductivity & Ampacity
- Copper Busbar: Higher conductivity (58 MS/m). Ampacity ~1.43× aluminum for same dimensions. Supports 2-4A/mm².
- Aluminum Busbar: Lower conductivity (35-37.7 MS/m). Requires ~30% larger cross-section to match copper’s ampacity. Supports 3-5A/mm².
Physical Properties
| Parameter | Copper | Aluminum |
| Density | 8.9g/cm³ (3.3× aluminum) | 2.7g/cm³ |
| Thermal Expansion | 16.5ppm/°C | 23.1ppm/°C |
| Melting Point | 1,085°C | 660°C |
Mechanical Performance
- Copper Busbar: Higher strength, resistant to deformation/creep. Ideal for high-stress environments.
- Aluminum Busbar: Softer, prone to creep. Requires surface treatment (e.g., tin plating) to reduce contact resistance.
Cost & Weight
- Copper Busbar: 2-3× higher cost per ampacity unit. Heavier (3.3× aluminum).
- Aluminum Busbar: ~40% cheaper. Lightweight (1/3 of copper’s weight).
Environmental Adaptability
- Copper Busbar: Stable at high temps (40°C ampacity = 85% of 25°C). Low oxidation impact.
- Aluminum Busbar: Sensitive to temp rise (40°C ampacity = 70-85% of 25°C). Forms high-resistance oxides.
Safety & Application
- Copper Busbar: Higher melting point reduces arc risks. Critical for data centers/substations.
- Aluminum Busbar: Lower melting point increases arc hazards. Suitable for residential/light industry.
Trade-offs
- Copper Busbar: Compact, durable, high ampacity. Expensive, heavy.
- Aluminum Busbar: Cost-effective, lightweight. Requires larger size, frequent maintenance.
Why Choose Best Technology as Copper Busbar PCB Manufacturer?
Reasons why choose us as copper busbar PCB manufacturer:
- Global Quality Certifications: ISO 9001 (quality management), ISO 14001 (environmental management).UL certification for flame resistance and current-carrying capacity.
- Competitive Pricing: Direct factory pricing with no middlemen, reducing costs by 15-20% compared to industry averages.
- Fast Lead Times: 24-hour prototype delivery for standard designs; 98% on-time delivery rate for bulk orders (500+ units).
- Premium Material Quality: Uses 99.9% purity copper (T2 grade) with third-party material certification.
- Advanced PCBA Integration: In-house SMT assembly lines supporting 0201 components and 0.3mm pitch BGAs.
- One-Stop Service: Covers design optimization → prototyping → mass production → PCBA assembly → testing.
- Rigorous QC Processes: 4-stage inspection: incoming material check → in-process monitoring → final electrical test → aging test.
- Customization Flexibility: Supports multi-layer busbars (up to 6 layers) and complex geometries; Accepts small-batch orders (as low as 10 units) with no MOQ restrictions.
- Engineering Support: Free DFM (Design for Manufacturability) analysis to optimize cost and performance. And 24/7 technical support via email/phone for troubleshooting.
Our Busbar PCB Capabilities
| Parameter | Value/Description |
| Copper Bar Spacing | 0.8-1.0mm |
| Copper Thickness | 1.0mm-3.0mm |
| Current Carrying Capacity | 50-300A |
| Bendability | Customizable bending upon request |
| Surface Finishing Options | ENIG (Electroless Nickel Immersion Gold), Immersion Silver, Gold Plating |
| Board Thickness | 3.0-6.0mm |
| Hole Wall Thickness | ≥25μm |
| Aspect Ratio | 1:6 or 1:7 (for 1.0mm copper thickness with minimum 0.7mm hole diameter) |
| Layer Count | Typical 3-4 layers; additional layers require design evaluation |
| Maximum Dimensions | Standard: 600×400mm; Double-sided: 900×600mm |
| Lead Time | 3-4 layers: 13-15 days; add 3 days per layer beyond 4 layers |
How to Get A Quote For Copper Busbar PCB Project?
Materials Required for Accurate Quotation:
Design Files
- 2D CAD drawings (DXF/DWG) or 3D models (STEP/IGES).
- Cross-sectional busbar dimensions (width × thickness).
Technical Specifications
- Current rating (amps) and allowable temperature rise.
- Copper material grade (e.g., T2, C110).
- Surface finish requirements (e.g., tin plating, nickel).
Production Details
- Order quantity (prototypes/bulk).
- Lead time expectations (urgent/standard).
Additional Requirements
- Certifications (UL, RoHS).
- Special testing (e.g., hi-pot, thermal cycling).
- Packaging preferences (anti-static, custom boxing).
Welcome to contact us if you have any request for copper busbar PCB: sales@bestpcbs.com.