Copper Busbar Machining Supplier for Energy Equipment

A copper busbar machining supplier cuts, drills, bends and finishes flat copper bar to a drawing, most often from Cu-ETP (EN CW004A), which has a conductivity of at least 58 MS/m in the soft condition. For energy and electrical equipment the same drawing package usually also holds aluminium busbars, sheet metal enclosures and auxiliary parts for wind turbines, each with its own material, finish and governing standard.

What parts does energy and electrical equipment need from a machining supplier?

This article covers three part families. Busbars carry current: flat bars with drilled or milled holes and slots, bent to shape and often plated. Enclosures and mounting parts are sheet metal and welded frames that must meet a degree-of-protection requirement. Wind turbine auxiliary parts, such as brackets, covers and cable supports, are structural or housing parts that fall under the turbine design standard.

The drawing requirement differs by family. A busbar is specified by conductivity, contact faces and hole positions. An enclosure is specified by its IP and impact rating. A turbine part is specified by structural loads and corrosion protection. The sector overview is on the energy and electrical equipment page.

Which material for busbars: Cu-ETP, Cu-OF or aluminium?

Bar for busbars is supplied to EN 13601:2021 (rod, bar and wire for general electrical purposes) or, for flat plate and strip, to EN 13599:2014. Within copper the choice is between Cu-ETP and Cu-OF; aluminium is the alternative when weight decides.

Table 1. Busbar materials, producer datasheet values

Source: Aurubis datasheets Cu-ETP (PNA 211, 2026-01) and Cu-OF (PNA 400, 2024-06); Hydro datasheet EN AW-6101A/B (Rev. 5, 2025-02). Copper minimums apply to the soft condition only; Hydro values are typical at 25 °C, not minimums.

Cu-ETP is the default. Its oxygen content matters only when the part is heated in a reducing atmosphere, for example during brazing in hydrogen-bearing gas. Aurubis rates Cu-ETP brazing as good and oxyacetylene welding as not recommended. A busbar that is only machined, bent and bolted does not care. A brazed or welded copper assembly should name Cu-OF on the drawing.

Aluminium trades conductivity for weight. From the table, equal resistance per metre needs 58 / 32.9, about 1.76 times the cross-section, and with the density ratio the aluminium bar weighs about 53 % of the copper bar (calculated from the table values, not a datasheet figure). Hydro lists busbar products among the uses of EN AW-6101. Aluminium also changes the customs picture, see below. More on alloys is in aluminium alloys for CNC machining.

How is a copper busbar machined, and what belongs on the drawing?

Copper is soft and ductile. Aurubis's datasheet for a low-oxygen Cu-ETP wire grade (PNA 213) gives a machinability index of 20 % against free-cutting brass CuZn39Pb3 = 100 %, and states that the index is a comparative rating, not a measured value. In practice that moves the effort from cutting to burr control: sharp tooling, defined edge breaks and a deburring note.

Conductivity also depends on processing. Aurubis states that cold deformation and small grain size reduce it, and that the 58 MS/m minimum applies to the soft condition only. If the busbar has to meet a conductivity value, say so on the drawing and ask for a measured value on the certificate.

Put these on the drawing:

• material grade and temper, with the standard and its year (EN 13601:2021)
• thickness and width of the bar and the length tolerance
• diameter and position tolerance of every hole that mates with another busbar or a terminal
• bend radius, bend direction and the position of the bend relative to the holes
• contact faces: flatness, roughness and whether plating covers them
• edge breaks and a deburring requirement

Untoleranced dimensions follow the general tolerance on the drawing. Our network works to ISO 2768-m as standard and tighter where the drawing specifies it, see ISO 2768 tolerance tables.

Which surface finish: bare, tin or silver?

Bare copper, tin and silver are the usual choices. A note such as "plated" is not a specification, so the drawing has to carry the decision.

Tin is one common electrodeposited finish. ISO 2093:1986 specifies requirements for nominally pure tin coatings on fabricated metal articles, matte or bright. Genorma's record of the ISO life cycle shows it as confirmed on 2022-09-09. Silver and nickel follow their own standards or the plater's specification. State the coating, the thickness in micrometres, the faces that carry it, and the test method for thickness. The thickness is set by the joint and the environment, not by the machining shop. Other coatings are covered in surface treatments for machined parts.

Which standards does the drawing package refer to?

A reference without a year can point at a withdrawn document.

Table 2. Standards for busbar, enclosure and turbine parts, status as of 30 October 2026

Source: DIN Media, IEC webstore, ISO catalogue pages and Genorma, as listed under Sources. Stability dates are IEC's own planning dates.

What differs for enclosures and wind turbine parts?

For enclosures, IEC 60529 classifies the degree of protection of an enclosure (the IP code), and IEC 62262 classifies protection against external mechanical impact (the IK code). Both apply to equipment up to 72.5 kV. The rating belongs to the finished enclosure as tested, so the drawing of a panel or door states the geometry, the material, the seam and weld requirement and the finish. For low-voltage assemblies, IEC 62208:2023 sets general requirements for the empty enclosure. The sheet metal process is described on the sheet metal page.

For wind turbine parts, IEC 61400-1 covers all turbine subsystems, including internal electrical systems, mechanical systems and support structures, and the IEC page adds that offshore installations bring further requirements in IEC 61400-3-1. The turbine maker's specification sets the corrosion class and paint system. The ISO 12944 series on paint systems for steel structures is the usual reference, and its part 1 is under revision as of 30 October 2026.

Do CBAM and customs rules apply to busbars from Turkey?

For copper, no. The Commission lists the CBAM sectors as cement, iron and steel, aluminium, fertilisers, hydrogen and electricity (Q&A 1.7, updated 15 October 2026). Copper is not among them. For aluminium, yes: the Commission's aluminium tables list bars, rods and profiles of aluminium (CN 7604) and sheet and strip (CN 7606), and CBAM has been in its definitive phase since 1 January 2026.

What counts is the CN code of the finished part, which the importer and customs broker decide. A steel enclosure or an aluminium busbar assembly may fall under a CBAM code or not. The working rules and the status of the 2028 extension proposal are in CBAM for steel and aluminium parts from Turkey. Customs duty and origin evidence for all of these parts follow the EU–Turkey customs union: 0 % duty on industrial goods in free circulation, with an A.TR movement certificate.

What should an RFQ for these parts contain?

1. Material grade, temper and standard with year, for example Cu-ETP CW004A to EN 13601:2021.
2. A conductivity requirement if one applies, and whether you want the measured value on the certificate.
3. Finish: coating, thickness, faces, and the thickness test method.
4. General tolerance class and individual tolerances for hole patterns and bends.
5. For enclosures, the IP and IK rating the finished unit must reach and the paint or powder specification.
6. For turbine parts, the corrosion class and coating system from the OEM specification.
7. The inspection certificate type you need, for example EN 10204 3.1, and a CAD file with the drawing.

Frequently asked questions

Which copper grade is used for machined busbars?

Cu-ETP (EN CW004A) is the standard electrical copper: at least 99.90 % Cu, at most 0.04 % oxygen and at least 58 MS/m (100 % IACS) in the soft condition. Cu-OF (CW008A) has the same minimum conductivity and is chosen when the busbar is brazed or welded, because it is not susceptible to hydrogen embrittlement.

What is the conductivity of Cu-ETP?

Aurubis lists at least 58 MS/m, equal to at least 100 % IACS, for the soft condition only. Cold deformation and small grain size lower it, so a hard-drawn or heavily worked bar needs its own measured value.

Can an aluminium busbar replace copper?

Yes, with a larger cross-section. Hydro gives a typical 32.9 MS/m for EN AW-6101 in temper T76 and 33.7 MS/m in T73, against at least 58 MS/m for Cu-ETP. Equal resistance per metre needs about 1.7 to 1.8 times the aluminium cross-section, and the bar then weighs roughly half as much.

Does CBAM apply to copper busbars?

No. The Commission lists cement, iron and steel, aluminium, fertilisers, hydrogen and electricity as the CBAM sectors, and copper is not among them. Aluminium bars, rods and profiles under CN 7604 are on the Commission's list of aluminium goods, so an aluminium busbar can be in scope. Status as of 30 October 2026.

Is IEC 62208:2011 still valid for empty enclosures?

No. IEC withdrew the 2011 edition on 2023-06-01. IEC 62208:2023 (edition 3.0) replaces it and applies to empty enclosures for assemblies up to 1 000 V AC or 1 500 V DC.

Sources

1. DIN EN 13601:2021-07, copper rod, bar and wire for general electrical purposes, current (DIN Media)
2. DIN EN 13601:2013-09, withdrawn, replaced by the 2021 edition (DIN Media)
3. EN 13601:2021, scope and product sizes (Genorma)
4. DIN EN 13599:2014-12, copper plate, sheet and strip for electrical purposes, current (DIN Media)
5. Aurubis, material datasheet Cu-ETP (PNA 211), EN_2026_01
6. Aurubis, material datasheet Cu-OF (PNA 400), EN_2024_06
7. Aurubis, material datasheet CuETP wire grade (PNA 213), EN_2024_11
8. Hydro, material datasheet EN AW-6101A/B, Rev. 5, February 2025
9. ISO 2093:1986, electroplated coatings of tin, confirmed 2022 (Genorma, ISO stage 90.93)
10. IEC 61439-1:2020, low-voltage switchgear and controlgear assemblies, general rules (IEC webstore)
11. IEC 62208:2023, empty enclosures for low-voltage switchgear and controlgear assemblies (IEC webstore)
12. IEC 62208:2011, withdrawn 2023-06-01 (IEC webstore)
13. IEC 60529:1989+AMD1:1999+AMD2:2013 CSV, IP code (IEC webstore)
14. IEC 62262:2002+AMD1:2021, IK code (IEC webstore)
15. IEC 61400-1:2019+AMD1:2025 CSV, wind energy generation systems, design requirements (IEC webstore)
16. ISO 12944-1:2017, status 90.92 with ISO/WD 12944-1 in development (ISO committee page)
17. European Commission, CBAM Questions and Answers, question 1.7 (updated 15 October 2026)
18. European Commission, Default values for the transitional period of the CBAM, aluminium table (22 December 2023)

Questions on a drawing? sales@ertas.engineering

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