Bending
O and H111 bar bends flatwise around a radius of about 1 × thickness; edgewise bends need larger radii. Harder tempers need more generous radii.
Electrical conductor guide
1350 and 1370 Electrical Aluminium Busbar
1350 is the standard electrical-conductor (EC) aluminium for busbar, with at least 99.50 % aluminium and a conductivity of about 61–62 % IACS; 1370 is a purer variant at 99.70 %. Rectangular EC busbar carries the same current as copper with about 1.64 times the cross-section but only half the weight. This guide covers grades, tempers, standards, sizes with resistance per metre, and the jointing practice that keeps aluminium bus reliable.
- Conductivity
- ≈ 61 – 62 % IACS
- Tempers
- H111, H112, H12; O for bending
- Standards
- ASTM B236 · EN 14121 · EN 755
- Sizes
- About 2 – 40 × 10 – 200 mm
Why 1350 and 1370 are used for busbar
Busbar is the backbone of switchgear, panel boards, bus ducts, transformers and battery systems. For a given resistance, the best conductor is the one that combines high conductivity with low density and cost, and on that measure EC aluminium is hard to beat.
Copper has a conductivity of 100 % IACS and a density of 8.89 g/cm³. 1350 aluminium reaches about 61 % IACS at a density of 2.705 g/cm³. To match the resistance of a copper bar, an aluminium bar needs about 1.64 times the cross-section, yet it weighs only about 50 % as much. Larger bars also have more surface area to shed heat, so in practice aluminium bus is often rated close to its copper counterpart at the same temperature rise.
1370 offers about one percentage point more conductivity because its impurity limits are tighter. It is used where every bit of loss reduction counts, for example in high-current DC bus for electrolysis and in large rectifier installations, while 1350 is the general-purpose choice. Where higher strength or creep resistance is needed, 6101 in T6, T61, T63 or T65 temper trades a few percent of conductivity for much higher strength.
Composition of 1350 and 1370 (wt %)
| Element | 1350 | 1370 |
|---|---|---|
| Silicon (Si) | ≤ 0.10 | ≤ 0.10 |
| Iron (Fe) | ≤ 0.40 | ≤ 0.25 |
| Copper (Cu) | ≤ 0.05 | ≤ 0.02 |
| Manganese (Mn) | ≤ 0.01 | ≤ 0.01 |
| Magnesium (Mg) | — | ≤ 0.02 |
| Chromium (Cr) | ≤ 0.01 | ≤ 0.01 |
| Zinc (Zn) | ≤ 0.05 | ≤ 0.04 |
| Boron (B) | ≤ 0.05 | ≤ 0.02 |
| Gallium (Ga) | ≤ 0.03 | ≤ 0.03 |
| Vanadium + titanium (V + Ti) | ≤ 0.02 | ≤ 0.02 |
| Others, each / total | ≤ 0.03 / ≤ 0.10 | ≤ 0.02 / ≤ 0.10 |
| Aluminium (Al) | ≥ 99.50 | ≥ 99.70 |
Registered Aluminum Association limits. In Europe the closest grades are EN AW-1350 and EN AW-1350A (EAl99.5); in the Russian system the EC grades are АД0Е and АД00Е. Note that the Russian digital number 1350 refers to a different alloy (АД35, an Al-Mg-Si grade), so always quote the full designation.
Electrical and mechanical properties
Electrical and physical properties (typical, 1350)
- Conductivity
- ≈ 61 – 62 % IACS (≈ 35.4 – 36 MS/m) at 20 °C
- Resistivity
- ≈ 0.0280 – 0.0283 Ω·mm²/m at 20 °C
- Temperature coefficient of resistance
- ≈ 0.0040 per °C at 20 °C
- Density
- 2.705 g/cm³
- Thermal conductivity
- ≈ 230 – 234 W/m·K
- Thermal expansion
- ≈ 23.5 × 10⁻⁶ /K
- Elastic modulus
- ≈ 69 GPa
Mechanical properties are low, which is acceptable for supported bus but must be considered at bolted joints and under short-circuit forces. Typical values published by the Aluminum Association for 1350:
| Temper | Tensile strength (typical) | Yield strength (typical) | Use |
|---|---|---|---|
| O | ≈ 83 MPa | ≈ 28 MPa | Edgewise and flatwise bending, flexible links |
| H111 / H112 | Between O and H12 | — | Extruded bar, as supplied |
| H12 | ≈ 97 MPa | ≈ 83 MPa | General rolled or drawn bar |
| H14 | ≈ 110 MPa | ≈ 97 MPa | Stiffer bar |
| H16 | ≈ 124 MPa | ≈ 110 MPa | Stiff bar, limited bending |
Values are typical, not guaranteed minimums. Certificates report the measured results for the lot.
Busbar standards
| Standard | Scope |
|---|---|
| ASTM B236 / B236M | Aluminium bars for electrical purposes (bus bars), 1350 in H12, H111 and H112 tempers. The combined edition replaced the separate inch and metric versions in 2023–24. |
| ASTM B317 / B317M | Extruded 6101 bus conductor bar, rod, tube and profiles |
| EN 14121 | Aluminium sheet, strip and plate for electrotechnical applications |
| EN 755-2 / EN 755-5 | Extruded bar: mechanical properties and dimensional tolerances for rectangular bar |
| IEC 60105 | Commercial-purity aluminium busbar material (older international recommendation still cited) |
| IEC 61439 | Low-voltage switchgear assemblies: temperature-rise verification of the finished busbar system |
Common sizes, weight and DC resistance
Supply range
- Thickness
- About 2 – 40 mm
- Width
- About 10 – 200 mm; wider bars cut from plate
- Length
- Standard 3 – 6 m; cut lengths to drawing; coiled bar for thin sections
- Edges
- Square, rounded or full-radius edges
- Finish
- Mill finish; tin, silver or nickel plating; insulating coating or sleeve
The table gives the mass and DC resistance at 20 °C for 1350 at 61.0 % IACS (0.028264 Ω·mm²/m). AC resistance is higher for thick or wide bars because of skin and proximity effects.
| Size (mm) | Area (mm²) | kg per m | DC resistance (µΩ/m) |
|---|---|---|---|
| 3 × 25 | 75 | 0.203 | 376.9 |
| 5 × 30 | 150 | 0.406 | 188.4 |
| 5 × 50 | 250 | 0.676 | 113.1 |
| 6 × 60 | 360 | 0.974 | 78.5 |
| 8 × 80 | 640 | 1.731 | 44.2 |
| 10 × 50 | 500 | 1.353 | 56.5 |
| 10 × 100 | 1000 | 2.705 | 28.3 |
| 10 × 120 | 1200 | 3.246 | 23.6 |
| 12 × 100 | 1200 | 3.246 | 23.6 |
| 12 × 150 | 1800 | 4.869 | 15.7 |
| 15 × 150 | 2250 | 6.086 | 12.6 |
| 20 × 200 | 4000 | 10.820 | 7.1 |
Bolted joints: how to make aluminium bus reliable
Most problems with aluminium busbar start at joints. Aluminium forms a hard oxide film within seconds, creeps slightly under sustained pressure and expands more than steel bolts. Good practice deals with each of these:
- Prepare the surfaceWire-brush or abrade contact faces and apply oxide-inhibiting compound immediately; or use plated (tin or silver) contact areas.
- Use enough contact area and pressureSize the overlap to the current, and use several bolts rather than one large bolt to spread pressure.
- Control creep and expansionUse Belleville (conical spring) washers and thick flat washers with steel bolts so pressure is maintained through heating cycles.
- Avoid galvanic attackWhere aluminium meets copper, use bimetallic plates, tin-plated contacts or copper-clad aluminium, and keep the joint dry.
- Torque and checkTighten to the specified torque and include joints in thermographic inspection.
Bending, drilling, plating and insulation
Punching and drilling
EC aluminium is soft; use sharp tools and lubricant to avoid burrs that raise local field stress.
Welding
TIG or MIG with 1100 / 1188-type filler keeps joint conductivity high; 4043 is easier to weld but lowers conductivity in the weld zone.
Plating
Tin is standard for contact faces; silver for high-current or high-temperature joints; nickel where wear or fretting is a concern.
Insulation
Epoxy powder coating, heat-shrink sleeving or PVC/silicone covers for compact and medium-voltage bus.
Cladding
Copper-clad aluminium bar gives copper contact surfaces on a light aluminium core.
Where EC aluminium busbar is used
- Low- and medium-voltage switchgear, panel boards and motor control centres
- Sandwich and air-insulated bus duct (busway) systems
- Transformer leads, secondary connections and winding strip
- Electrolysis, smelting and electroplating DC bus (often 1370)
- Solar inverters, wind turbines and battery energy storage
- Data centre power distribution and UPS systems
References and standards
- ASTM B236 / B236M – Standard Specification for Aluminum Bars for Electrical Purposes (Bus Bars)
- EN 14121 – Aluminium and aluminium alloys: sheet, strip and plate for electrotechnical applications
- IEC 61439-1 – Low-voltage switchgear and controlgear assemblies
- The Aluminum Association – Aluminum Electrical Conductor Handbook
- ASTM B193 – Standard Test Method for Resistivity of Electrical Conductor Materials
1350 / 1370 aluminium (aluminum) busbar: frequently asked questions
What is the conductivity of 1350 busbar?
About 61–62 % IACS at 20 °C, equal to a resistivity of roughly 0.028 Ω·mm²/m. 1370 is slightly higher at about 62 %.
How much bigger must an aluminium busbar be than copper?
About 1.64 times the cross-section for the same DC resistance. It still weighs about half as much as the copper bar.
Which temper should I order for bending?
O or H111 for tight flatwise and edgewise bends. H12 and harder tempers are stiffer and need larger bend radii.
Is 1350 or 6101 better for busbar?
1350 conducts better; 6101 in T6, T61 or T63 is much stronger and resists creep at bolted joints. Choose 6101 when the bar carries mechanical load.
Can aluminium busbar be bolted to copper?
Yes, with tin-plated contacts, bimetallic transition plates or copper-clad aluminium, oxide-inhibiting compound and spring washers, and with the joint kept dry.
Do you cut and plate busbar to drawing?
Yes. We supply 1350 and 1370 busbar cut, drilled, bent, plated or insulated to drawing, with mill certificates, shipped worldwide.
Need EC aluminium busbar?
Send sizes, lengths, temper and finishing or a drawing. We will reply with availability, certification and a delivered price.
