Low-voltage busbar connection material

Low-voltage busbars are typically made of copper or aluminum, while their insulation uses materials like bulk molding compounds (BMC), sheet molding compounds (SMC), or thermoplastic heat-shrink tubing.

Conductive Materials

Copper is the most common busbar material due to its high electrical conductivity (100% IACS), excellent thermal performance, and durability, making it ideal for compact low-voltage assemblies where efficiency is critical. Aluminum is also widely used, offering significant weight reduction (about 66% lighter than copper) and cost savings of 30–50%, though its conductivity is lower (around 61% IACS) and it requires careful mechanical design to handle thermal expansion. In some cases, copper alloys or plated copper (tin, silver, or nickel) are used to improve corrosion resistance or surface conductivity.

The choice between copper and aluminum depends on space constraints, budget, current-carrying requirements, and environmental conditions. Insulating MaterialsLow-voltage busbars require insulation to prevent short circuits and ensure safety. Common insulating materials include: Bulk Molding Compounds (BMC) and Sheet Molding Compounds (SMC): These are fiberglass-reinforced thermosetting plastics that provide high dielectric strength, thermal resistance, and mechanical stability.

They are used in switchgear, distribution panels, and renewable energy systems to support busbars while maintaining safe clearances. Fiberglass-reinforced DMC/BMC: Offers excellent dimensional stability, heat resistance, and mechanical strength, suitable for compact LV/HV assemblies and capable of withstanding short-circuit forces. Thermoplastic heat-shrink tubing (e.g., Raychem LVIT): Flexible tubing that shrinks tightly over busbars when heated, providing UV resistance, flame retardancy, and long service life for both indoor and outdoor applications up to 1 kV.

Standards and Design ConsiderationsLow-voltage busbars are typically designed according to IEC 61439, which specifies voltage ratings up to 1000 V AC and 1500 V DC, thermal limits, and assembly requirements. Insulators must maintain adequate creepage distances, withstand mechanical stresses from thermal expansion and electromagnetic forces, and ensure minimal leakage currents. For example, insulators can handle axial tensile forces up to 4000 N and bending loads of 5000 N, while maintaining alignment tolerances within ±0.

5 mm.

Summary

Conductors: Copper (high conductivity, durable) or Aluminum (lightweight, cost-effective). Insulators: BMC, SMC, DMC, or thermoplastic tubing for electrical isolation and mechanical support. Applications: Switchgear, distribution panels, renewable energy systems, motor control centers.

Standards: IEC 61439 ensures safe voltage, thermal, and mechanical performance. Selecting the right combination of busbar material and insulation depends on current requirements, space, cost, environmental conditions, and compliance with safety standards.