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Safety Distance and Key Considerations for Low-Voltage Busbars

03/19 Silin Wu

Proper planning of safety distances in low-voltage busbar design and installation is critical for ensuring electrical performance, operational stability, and equipment safety. Adhering to industry standards such as IEC 61439 (low-voltage switchgear and controlgear) and UL 891 (switchboards) enhances reliability across various applications. Key technical considerations include:

Safety Distance for Low-Voltage Busbars

1. Busbar Clearance Requirements

The phase-to-phase and phase-to-ground distances depend on rated voltage, environmental conditions, and insulation levels. Recommended values based on IEC 60664-1 (creepage distances):

  • ≤690V: Air clearance ≥10mm, creepage distance ≥14mm

  • 1000V: Air clearance ≥18mm, creepage distance ≥22mm

  • High pollution or humidity: Increased creepage distance or insulation coatings (e.g., PVC dipping, epoxy encapsulation, or high-temperature-resistant coatings) to mitigate surface discharge risks.

2. Clearance Between Busbars and Enclosures (Grounded Metal Parts)

Adequate spacing prevents short circuits and enhances system safety:

  • Bare copper busbars: Minimum clearance ≥20mm to avoid phase-to-phase or phase-to-ground faults.

  • Insulated busbars: Insulation allows for reduced clearance but must meet IEC 60664 or UL 746C dielectric strength requirements.

  • Compact busbar trunking or confined spaces: Consider ventilation to manage thermal effects, preventing excessive temperature rise that may impact insulation and current-carrying capacity.

3. Busbar Arrangement and Support Spacing

Proper busbar layout and mechanical support improve EMC, mechanical strength, and long-term stability:

  • Parallel arrangement: Uniform spacing minimizes EMI and skin effect losses, ensuring balanced current distribution.

  • Support insulator spacing: Typically 300mm–500mm to withstand mechanical stress from short-circuit forces.

  • High-current applications (>2000A): Reinforced busbar supports and compliance with IEC/TR 61641 (internal arc fault testing) to ensure high short-circuit withstand capability.

4. Busbar Connections and Bending Safety

Proper design of busbar joints and bends enhances reliability and long-term performance:

  • Bolted connections: Allow for thermal expansion compensation and use high-strength conductive fasteners per IEC 60947-1.

  • Bend radius: Recommended R≥5mm to reduce electric field concentration and prevent localized insulation breakdown.

  • Copper-aluminum transition: Use bimetallic washers or specialized transition terminals to minimize contact resistance and prevent galvanic corrosion.

5. Safety Considerations for Special Applications

Different environments require specific protective measures to ensure system reliability:

  • EV charging stations & energy storage: Higher IP ratings (IP54+, per IEC 60529) and heat-resistant insulation materials (PI, PFA, ceramic coatings) for high-load conditions.

  • Switchgear busbars: Heat-shrink insulation or surface coatings improve contamination resistance and reduce arc discharge risks, complying with IEC 62271-200 (high-voltage switchgear) and IEC 61439 (low-voltage distribution).


Optimizing safety distances and structural design in low-voltage busbar applications enhances system safety and long-term reliability while reducing electrical failure risks. Compliance with IEC and UL standards ensures global market compatibility and engineering reliability. RHI provides low-voltage copper and aluminum busbars with diverse insulation and plating options. Contact us for details. 


label: Low Voltage Busbars, Panel Busbar