C11000 ETP copper is an electrolytically refined, oxygen-bearing copper with a minimum 99.90% copper content and about 101% IACS electrical conductivity when annealed. Its combination of conductivity (the highest of the commercial coppers), formability, and corrosion resistance makes it a reliable choice for electrical conductors, welding support components, heat-transfer equipment, and general fabrication.

C11000 ETP Copper Composition and Designations

C11000 ETP copper contains a minimum of 99.90% copper, with silver counted as part of the copper value. It also contains residual oxygen, typically around 0.02–0.04%. That oxygen content is a defining characteristic of electrolytic tough pitch (ETP) copper and is one of the main differences between C11000 and oxygen-free copper grades.

Electrolytic tough pitch means that C11000 is produced from electrolytically refined copper and then refined to a controlled oxygen level, resulting in a high-conductivity copper that is easy to fabricate and widely available for industrial applications. The oxygen content also means C11000 can be susceptible to hydrogen embrittlement under certain welding and brazing conditions, so you should consider material selection when those processes are involved.

C11000 goes by several different names and designations, including C110, copper 110, 110 copper, CDA 110, UNS C11000, C1100, Cu-ETP, ETP copper, and alloy 110. These designations generally refer to the same commercially pure, electrolytic tough pitch copper grade.

C11000 ETP Copper Properties

C11000’s usefulness primarily comes from its electrical and thermal conductivity, but it also has good formability and corrosion resistance. The values below are for the annealed condition, unless otherwise noted. Keep in mind that mechanical properties can change considerably with temper.

Property	Value
UNS number	C11000
Common designations	C110, CDA 110, C1100, Cu-ETP, alloy 110
Nominal composition	99.90% Cu min (Ag counted as Cu)
Density	0.322 lb/in³ (8.91 g/cm³) at 68°F
Electrical conductivity	101% IACS, annealed at 68°F
Thermal conductivity	226 Btu/ft·hr·°F at 68°F
Tensile strength	32–66 ksi, temper dependent
Yield strength	10–53 ksi, temper dependent
Hardness	up to 62 HRB, extra spring temper
Modulus of elasticity	17,000 ksi
Coefficient of thermal expansion	9.4 × 10⁻⁶ per °F (68–212°F)
Melting point	1,981°F liquidus / 1,949°F solidus
Machinability rating	20 (free-cutting brass = 100)
Applicable specs	ASTM B152, ASTM B187, ASTM B370

Applications

C11000 is usually the right choice when electrical conductivity is your priority. Its high conductivity allows current to move efficiently, while its formability makes it practical for components that need to be bent, shaped, machined, or fabricated.

Electrical and Conductor Components

C11000 copper is widely used for electrical and electronic components where conductivity is the goal. At approximately 101% IACS in the annealed condition, it efficiently carries electrical current while staying relatively easy to fabricate.

Common applications include:

Busbars
Connectors
Terminals
Grounding components
Switchgear parts
Wire
Cable
Bus conductor

Resistance Welding Support Components

C11000 can be an excellent conductor within a welding system, but it is not an RWMA electrode alloy. So when the application calls for a component that needs to conduct current efficiently, C11000 can make sense. But when the component itself is the working electrode face and must withstand repeated heat, pressure, and wear, you should go with a higher-strength RWMA copper alloy.

Applications include:

Shunts
Current-carrying arms
Backing bars
Transformer connections
Ground straps
Other conductive components

Heat Transfer and Process Equipment

C11000 combines high electrical conductivity with strong thermal conductivity (about 226 Btu/ft·hr·°F at 68°F) making it useful for components designed to move heat efficiently.

Applications include:

Heat exchanger components
Cooling plates
Thermal conductors
Process equipment

Architectural and General Fabrication

C11000 is also used in jobs where formability, appearance, and corrosion resistance take precedence over high mechanical strength. Its good fabrication characteristics make it useful for roofing, flashing, decorative components, and general sheet and plate fabrication.

C11000 can be bent, formed, soldered, drilled, and machined for a wide range of designs, and it also generally resists:

Mineral acids
Organic acids
Carbolic, citric, formic, oxalic, tartaric, and fatty acids
Solutions containing sulfur
Solutions used in pulp mills
Alkaline fused with sodium
Salt solutions
Water, all potable waters

How C11000 Compares

When it comes down to choosing between copper grades, the defining factor is usually what the application actually requires. C11000 offers an excellent combination of conductivity, availability, formability, and cost; other grades become preferable when purity or resistance to specific processing conditions is the priority.

C11000 vs. C10100 Oxygen-Free Copper

While C11000 contains a minimum of 99.90% copper along with controlled residual oxygen, C10100 is a 99.99% pure oxygen-free copper grade. C10100 is the better choice when the job requires extremely high purity or hydrogen embrittlement during welding or brazing in a reducing atmosphere is a concern.

C11000 is considered the workhorse thanks to the fact that it has nearly identical conductivity, but it has better availability and is the more economical choice. If you’re not brazing in a reducing atmosphere or chasing ultra-high-purity, C11000 is usually the right call. For jobs where oxygen content is the deciding factor, consider C10100 oxygen-free copper.

C11000 vs. RWMA Electrode Alloys

While C11000 is great for conductivity, pure ETP copper is relatively soft and can soften under the temperatures and mechanical loads that an electrode face encounters. That’s why RWMA copper alloys exist.

The simplest way to think of it is this: C11000 is often the conductor material in a welding cell; RWMA copper alloys are designed for the working face and other demanding welding components. If you’re selecting material for an electrode, electrode holder, welding die, or other resistance-welding component, the right grade depends on the heat, pressure, wear, and conductivity requirements of the job.

Explore NSRW’s RWMA copper alloys to compare your options.

Available Forms and Sizes

NSRW stocks C11000 ETP copper in a wide variety of forms and sizes, including rounds, squares, hexagons, rectangles, plates, as well as custom shapes. Available tempers range from soft and annealed to half hard and hard, depending on the form and application.

If you’re looking for a particular dimension, we can provide custom sizes, cut-to-length material, and custom shapes to fit your specifications. No worrying about how to make standard stock work with your job.

Whether you need a length of round bar for a conductive component, plate for fabrication, or a custom shape for a welding application, NSRW can help you find the right form and specification.

Shop C11000

How NSRW Supplies C11000 ETP Copper

We don’t simply point you toward a copper grade and send you a catalog number to find what you need on your own. If you’re not sure whether C11000 is the right material—or whether you actually need an RWMA copper alloy—our team can discuss and help you work through the application and what it calls for.

We keep C11000 ETP copper in inventory, offer cut-to-length and custom-shape capabilities, and provide in-house machining for applications that need more than raw material. And most stock sizes can ship the same day, so your project and production lines keep moving without unnecessary delays.

We supply both conductive copper stock and resistance welding electrodes with technical guidance from people who understand how the materials work in the equipment, not just what’s printed on the spec sheet.

Frequently Asked Questions

What is C11000 copper?

C11000 is an electrolytic tough pitch copper grade containing a minimum of 99.90% copper. It is an oxygen-bearing copper known for its high thermal and electrical conductivity, corrosion resistance, and good formability.

What does ETP stand for in copper?

ETP stands for electrolytic tough pitch. ETP copper is electrolytically refined and contains a controlled amount of residual oxygen. C11000 is the standard designation for this type of high-conductivity copper.

Is C110 copper the same as C11000?

Yes, C110 and C11000 refer to the same copper grade; you may also see it identified as CDA 110, C1100, copper 110, 110 copper, Cu-ETP, or alloy 110.

What is C11000 copper used for?

C11000 copper’s high conductivity makes it commonly used in electrical applications, including busbars, electrical and electronic conductors, connectors, terminals, grounding components, welding support components, heat-transfer equipment, roofing, flashing, and general fabrication.

What is the difference between C11000 and C10100 copper?

C11000 contains a minimum of 99.90% copper and controlled residual oxygen, while C10100 is oxygen-free copper with a minimum 99.99% copper content.

What is the electrical conductivity of C11000 copper?

C11000 has an electrical conductivity of approximately 101% IACS in the annealed condition at 68°F; however, conductivity can vary with temper and processing condition.

Can C11000 copper be welded?

Yes, C11000 can be welded using processes such as soldering, brazing, gas-shielded arc welding, oxyacetylene welding, and butt welding.

What tempers is C11000 copper available in?

C11000 is available in a range of tempers, from soft or annealed through half hard and hard conditions, with the appropriate temper depending on the forming, strength, conductivity, and fabrication requirements of the job.

Shop C11000 ETP Electrolytic Copper

If you need C11000 ETP copper for an electrical, welding, heat-transfer, or fabrication application, we have it. NSRW offers stock material, custom shapes, and cut-to-length options, along with technical support if you’re unsure which copper grade or temper is right for the job.

Most stock sizes can ship the same day, so you can get the material you need without extending your project timeline.Copper C110 MSDS