Recommended Wire Gauge (AWG/mm²) for Various Solar Street Light System Currents
Learn how to choose the right wire gauge (AWG or mm²) for different current levels in solar street light systems to ensure safety, efficiency, and long-term durability.
Choosing the correct wire gauge is crucial for the safety and performance of solar street lighting systems. Wire size directly affects energy efficiency, voltage drop, and heat generation. This article outlines the appropriate cable sizes for varying current levels and provides design considerations for installers and engineers.

Why Wire Gauge Matters in Solar Street Light Systems
Solar systems consist of photovoltaic panels, batteries, LED luminaires, and controllers—all interconnected with wiring. Inappropriate wire sizing can lead to:
- Excessive voltage drop
- Power loss
- Overheating
- System failure or fire hazard
Recommended Wire Gauge by Current Rating
| Current (Amps) | Wire Gauge (AWG) | Cross Section (mm²) | Recommended Max Distance (12V system) |
|---|---|---|---|
| 1–5 A | 16 AWG | 1.5 mm² | 7–12 meters |
| 6–10 A | 14 AWG | 2.5 mm² | 10–18 meters |
| 11–15 A | 12 AWG | 4.0 mm² | 15–25 meters |
| 16–20 A | 10 AWG | 6.0 mm² | 20–30 meters |
| 21–30 A | 8 AWG | 10 mm² | 30–40 meters |
| 31–50 A | 6 AWG | 16 mm² | 40–50 meters |
Note: Maximum wiring distance depends on system voltage, environment, and allowable voltage drop (usually 3–5%).
Key Considerations When Choosing Cable Size
- Current load: Based on LED and system design.
- Voltage drop allowance: Keep below 5% of system voltage.
- Cable length: The longer the distance, the thicker the wire required.
- Installation conditions: Underground or hot areas require heat-resistant, higher-rated cables.
- Conductor material: Copper offers lower resistance than aluminum. If using aluminum, increase size by one level.
Example Calculation
System: 40W solar LED light, 12V system
Current: 40W / 12V = 3.3A
Distance: 15 meters one way
Recommended wire: 2.5 mm² (14 AWG) to keep voltage drop <5%
Voltage Drop Formula
Voltage Drop (V) = 2 × Length × Current × Resistance per meter
Reference resistance:
Copper: ~0.0175 Ω·mm²/m
Aluminum: ~0.0285 Ω·mm²/m

Frequently Asked Questions (FAQ)
Q1: Can I use a thinner wire to save cost?
A: Not recommended. Undersized wires cause overheating, energy loss, and may fail to meet safety codes.
Q2: What is the difference between AWG and mm²?
A: AWG is used mainly in North America, while mm² is the metric standard. For example, 14 AWG ≈ 2.5 mm².
Q3: Are cable sizes the same for LED and battery connections?
A: Not necessarily. Size depends on current drawn and cable length between each component.
Q4: Do higher voltage systems need smaller wires?
A: Generally yes, because higher voltage means lower current, reducing the wire size requirement for the same power.
Q5: Is wire color important?
A: While not affecting functionality, standard color coding helps safety and maintenance (e.g., red = positive, black = negative).
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