Copper Grades for Busbars: Do You Really Need Oxygen-Free Copper?

If you are specifying copper grades busbars for switchgear, power distribution, or industrial systems, you will quickly run into a common question: Do we really need oxygen-free copper?

It is easy to assume “oxygen-free” must be better. In reality, many busbar projects perform perfectly well with standard electrical grades, and over-specifying can add cost and lead time without improving performance.

At ILF, we help engineers and buyers in selecting practical copper grades that will produce trustworthy results. We stock and sell copper and aluminium in the UK, and we produce busbars to high specifications using robust processes, explicit capability control, and consistent lead time communication. This page defines what ‘oxygen-free’ implies, why it is important, and what normally matters more.

Why Copper Grades Matters in Busbar Design

Busbars look simple, but their performance depends on the right material choice, the right format, and the right finishing. Selecting the right grade ensures:

• Consistent conductivity across joints and connections.
• Reliable bending or machining during manufacture.
• Compatibility with plating or tinning processes.
• Predictable performance in heat and corrosion environments.

Getting it right the first time saves money on materials that provide minimal benefit in real-world installations.

Copper Basics: Conductivity, Purity, and Oxygen Content

Copper is coveted for its high electrical conductivity, second only to silver. This conductivity is directly related to metal purity: fewer impurities allow electrons to pass more freely across the structure.

The refining process introduces trace amounts of oxygen into most copper grades. Oxygen aids in the removal of undesirable gases and is normally present in sufficient quantities to maintain performance.

However, eliminating practically all oxygen results in “oxygen-free” copper, which some believe is superior for all electrical applications. In actuality, this is not always the case.

The Main Copper Grades Used for Busbars

Busbars are made of Electrolytic Tough Pitch (ETP) and Oxygen-Free High Conductivity copper. Engineers prefer them for their purity, electrical conductivity, and reliability.

Electrolytic Tough Pitch (ETP) copper (C11000 / CW004A):

• The most common choice for copper busbars in power distribution, switchgear, and panel boards
• At least 99.90% copper
• High electrical conductivity for everyday electrical duty
• Good corrosion resistance in typical indoor environments
• Usually, the best balance of performance, availability, and cost

Oxygen-Free High Conductivity (OFHC) copper (C10100 / CW008A):

• Higher purity, typically above 99.95%, with very low oxygen content
• Chosen for specialist needs such as vacuum applications and certain high-temperature duties
• This type of copper is helpful in joining processes that require a lower oxygen content.
• Often specified when a customer standard explicitly requires it

T2 copper:

• High-purity copper that still contains oxygen
• Known for good ductility (it bends and forms well) and strong conductivity
• Common in electrical components in some markets and specifications

Silver-bearing copper (0.03-0.12% silver):

• Copper with a small amount of silver added for better strength at higher temperatures
• Resists softening when operating temperatures rise
• Keeps electrical conductivity high while improving mechanical stability

Machinability-focused copper (for example, sulphur copper):

• Selected when machining speed, tool life, or clean cutting is a priority
• Used where part features and tolerances make manufacturability important
• Typically chosen for production efficiency rather than maximum conductivity

People choose these materials to reduce energy loss, maintain joints and conductors, and meet mechanical needs. When part design prioritises manufacturability, they choose sulphur-copper for easier machining.

Oxygen-Free vs ETP: What Is the Real-World Difference?

In day-to-day power distribution, ETP and oxygen-free copper often behave very similarly electrically. Both are highly conductive and widely used in current-carrying components. Where they differ is usually not “how much current it carries”, but how the material behaves during certain joining processes or in specific service environments.

The simplest way to think about the real-world differences:

Audio and signal transmission:

• People often choose OFC because it has slightly higher purity and can reduce resistance.
• In normal speaker cable lengths, you will not usually hear a difference between ETP and OFC.
• If you run long cable lengths, use high-frequency signals, or work with very sensitive data lines, OFC can help keep the signal cleaner and more consistent.

High-temperature and joining work:

• If you braze or weld copper, or the part operates in a hydrogen-rich environment, ETP can develop cracks or voids (often called hydrogen sickness).
• OFC avoids this risk, which is why teams specify it for certain high-heat or specialist environments.

Flexibility and durability:

• OFC tends to handle repeated bending and vibration better.
• It has fewer oxide particles inside the metal, so it is less likely to fatigue over time in flexible or moving setups.

Corrosion and oxidation:

• OFC generally oxidises more slowly than ETP.
• This can help in applications where the surface stays exposed for long periods or where stable contact surfaces matter.

Summary Table

Feature	ETP (C11000)	Oxygen-Free (C10100/C10200)
Purity	99.9%	99.95% – 99.99%
Oxygen Content	100-650 ppm (0.02-0.05%)	<10 ppm (<0.001%)
Conductivity	~100% IACS	101% – 102% IACS
Embrittlement	High risk (above 400°C)	Resistant
Cost	Low	High
Typical Use	General Wiring/Power	Audio, Data, Vacuums, Welding

For most everyday electrical work, ETP does the job well. Choose OFC only when the application is a specialist and needs higher performance.

When Oxygen-Free Copper Is Worth It

Oxygen-free copper can be justified when:

• The part will undergo vacuum brazing or hydrogen atmosphere heat treatment.
• Extreme cleanliness or minimal outgassing is required (such as in electronics or semiconductor production).
• Very high precision machining or ultra-smooth surfaces are specified.
• The component will operate in an environment where even minor oxide formation must be avoided.

In these specialist contexts, ILF can supply C101 or C102 copper flats and strips with full traceability and certification.

When You Usually Do Not Need Oxygen-Free Copper

For many mainstream copper busbar builds, oxygen-free copper is not necessary, particularly when:

• The design uses bolted joints with excellent contact preparation.
• The joining approach is standard for switchgear and distribution assemblies.
• The environment is typical for indoor electrical installations.
• Your key concerns are busbar size, drilling, bending, and repeatable fit.

In these cases, ETP is often specified because it is well understood, widely available, and cost-effective without compromising real-world performance.

Manufacturing and Supply Considerations

Grade choice is only one part of a successful busbar order. How the bar is produced, finished, and supplied can have a bigger impact on installation speed and site issues.

At ILF, we support projects where copper busbar suppliers need to do more than just deliver material. Common requirements include:

• Supplying copper flat bar or copper strip in controlled sizes
• Producing parts to drawing with clean, consistent machining
• Adding a round edge where handling, clearance, or insulation interfaces matter
• Providing finishing support, including surface preparation where required
• Offering tinned copper options when corrosion control or connection stability is part of the design intent

Because we work within ISO 9001:2015 processes, we focus on repeatable outputs: specification control, traceable communication, and reliable UK fulfilment for urgent orders and planned schedules.

Factors to Consider Before Choosing a Copper Grades

Before specifying a grade, it helps to weigh the following factors:

• Electrical performance: Is conductivity above 99.9% IACS essential? For most designs, ETP suffices.
• Joining method: Will the busbar be welded, brazed, or bolted? ETP handles all except hydrogen brazing.
• Corrosion resistance: Is tin plating or coating required for environmental protection?
• Mechanical processing: Does the design involve bending, punching, or CNC machining?
• Availability and lead time: Oxygen-free material may have longer procurement times.
• Cost and sustainability: Choosing the highest grade only when necessary helps manage project budgets responsibly.

With these points clarified, choosing becomes much easier – and often, the standard grade offers all the reliability needed.

Bringing It All Together

Both oxygen-free and ETP copper operate well electrically, but with different benefits. In vacuum processing or extreme purity settings, C101 works. C110 (ETP) is the most efficient and popular approach for industrial and electrical busbar installations.

Let ILF help you match material specifications for lower project risk, reliable supply, and predictable performance. Our expert team helps engineers and consumers choose precision copper busbars for installation.

Submit your drawing or specification, and we will recommend the best way to produce and supply copper busbars for your project.