Aluminum Busbar: Benefits, Properties, Standards, and When It Beats Copper

Aluminum Busbar:  When It Beats Copper

Last updated: August 2025

Aluminum busbars are widely used in low-voltage assemblies and busway. When engineered correctly, they offer meaningful weight and material-cost advantages versus copper without compromising safety or performance. This guide explains the properties of electrical-grade aluminum (6101), relevant standards, practical design notes, and a spec table to help you decide when aluminum is the right choice.

New to busbars inside panels? See our Switchboard Busbar Guide and the companion Copper vs. Aluminum Busbar Comparison.

What is an aluminum busbar?

A busbar is a rigid, typically flat conductor used to distribute power within switchboards, MCCs, busway, and energy storage packs. Electrical-grade aluminum busbars are commonly extruded from alloy 6101 in tempers such as T6/T61 (intended for conductor applications per ASTM B317). Compared with copper, aluminum needs a larger cross-section to deliver the same ampacity, but it weighs about one-third as much and the raw material typically costs less.

Aluminum busbar properties (6101 alloy)

Conductivity and temperature-rise

Electrical-grade 6101-T6/T61 typically provides ~55–60% IACS conductivity (with 55% IACS commonly cited as a minimum for T6). Because copper (C110/ETP) is ~100% IACS, aluminum busbars are sized wider/thicker to maintain acceptable temperature rise at the rated current. In certified assemblies, temperature rise is demonstrated by design verification per IEC 61439.

Density, stiffness, and thermal expansion

• Density: ≈ 2.70 g/cm³ for aluminum 6101 vs ≈ 8.9 g/cm³ for copper. The weight advantage reduces handling effort and structural/support loads.
• CTE (thermal expansion): aluminum ≈ 23 µm/m·K vs copper ≈ 16–17 µm/m·K. Designs must accommodate movement at joints and supports during load/temperature cycles.

Implication: If your enclosure or busway can accept a modestly larger section, aluminum can meet performance targets while reducing mass and material spend.

Aluminum vs copper: when aluminum wins

• Weight matters: ~3× lower density eases lifting, transport, and seismic/support design.
• Budget matters: Global commodity data (see table) shows aluminum’s average raw-material price is significantly lower than copper (figures are indicative, USD, and subject to change).
• Space allows a larger section: A wider/thicker bar can match copper ampacity with excellent heat dissipation.
• Controlled joint quality: With proper plating, surface prep, and torque, aluminum joints achieve low resistance and stable performance.

Prefer copper when space is extremely tight, the highest stiffness at a given bar size is required, or you must match legacy copper geometries without re-verification.

Standards you should know

• IEC 61439 (low-voltage assemblies): requires temperature-rise verification at rated current for conductors and joints (by testing or defined comparison/assessment).
• IEC 60865-1: methods to calculate electromechanical forces on rigid conductors during short-circuits; used to choose support spacing/bracing.
• UL 857 (busway, North America) and other applicable assembly standards in your market: use manufacturer test data for the specific product line.

Design & installation notes for aluminum busbars

Jointing, plating, oxidation control

• Use tin-plated (or silver-plated where specified) contact surfaces to minimize contact resistance.
• Prepare/clean mating surfaces per supplier instructions; apply antioxidant compound where required.
• Tighten to the specified torque; follow any re-torque guidance after initial thermal cycling.

Sizing, supports, clearances

• Size for ampacity and temperature-rise limits (IEC 61439).
• Select insulators/support spacing based on short-circuit forces (IEC 60865-1) at the assembly’s prospective fault current.
• Maintain required creepage/clearance distances; consider airflow around larger sections.

Material call-out (electrical-grade)

• Specify Al 6101 in T6/T61 temper (or supplier-equivalent), with required plating/finish (commonly tin).
• Request material certificates and design-verification evidence with your RFQ.

Aluminum (6101-T6) vs Copper (C110/ETP) — key properties & indicative cost

Notes: Values are typical room-temperature properties for 6101-T6 and C110/ETP. Prices are indicative monthly averages (USD/mt, May 2025) from the World Bank “Pink Sheet” and subject to change. Always confirm with current supplier datasheets and official test reports.

Quick selection guidance

• Your design can accept a larger bar → aluminum is often the best value (lighter, lower raw-material cost).
• Space is very tight or stiffness at a given size is critical → copper may be the better fit.
• In all cases, verify temperature rise and short-circuit forces per the applicable standard.

RFQ checklist

• Rated current & duty profile; ambient and enclosure type
• Max allowable temperature rise; target standard (e.g., IEC 61439, UL 857)
• Prospective short-circuit current & duration; desired support spacing
• Alloy & temper (e.g., Al 6101-T6/T61) and finish (tin-plated)
• Joint hardware, torque specs, antioxidant requirement
• Insulation (if any), hole patterns, bending radii, labels/marking
• Documentation required: test reports/design verification, material certificates

Related reading & products

• Switchboard Busbar Guide
• Copper vs. Aluminum Busbar Comparison

Sources (indicative, for reference)

• Hydro Aluminium, “Alloy 6101 datasheet” (properties: density, CTE).
• Copper Development Association, “Copper and Copper Alloys—Physical Properties” (IACS baseline, density).
• Tri-City Extrusion / industry data for 6101 electrical conductivity (min 55% IACS; typical 57–60% IACS).
• World Bank, “Pink Sheet” Metals Prices—Monthly Averages (USD/mt, May 2025).
• Schneider Electric technical articles on IEC 61439 temperature-rise verification; BEAMA guidance on verification by assessment; IEC 60865-1 short-circuit forces overview.