C11000 ETP Copper: Electrolytic Tough Pitch for Electrical Use
ASTM B152/B187 · Published: 2026-06-02 · Updated: July 2026
C11000 Electrolytic Tough Pitch (ETP) copper is the most common commercially pure copper grade, containing ≥99.90% Cu with controlled oxygen (0.02-0.04%). It achieves the highest electrical conductivity of any commercial metal (101% IACS...
C11000 Electrolytic Tough Pitch (ETP) copper is the most common commercially pure copper grade, containing ≥99.90% Cu with controlled oxygen (0.02-0.04%). It achieves the highest electrical conductivity of any commercial metal (101% IACS minimum), making it the global standard for electrical bus bars, power cables, transformer windings, and electrical connectors. ETP copper also provides excellent thermal conductivity (391 W/m·K) for heat exchangers and plumbing. Soft-soldering and brazing are straightforward; however, ETP is susceptible to hydrogen embrittlement during welding or high-temperature brazing in reducing atmospheres due to internal steam formation at Cu2O particles.
Quick Facts
| Category | Copper Alloy |
| Standard | ASTM B152/B187 |
| Density | 8.94 g/cm³ |
| Yield Strength | 69 MPa (10 ksi) annealed; 310 MPa (45 ksi) hard |
| Tensile Strength | 220 MPa (32 ksi) annealed; 380 MPa (55 ksi) hard |
Global Equivalents & Cross-Reference
| Alternative Standard / Grade | Action |
|---|---|
| EN Cu-ETP | Compare |
| CW004A | Compare |
| JIS C1100 | Compare |
| T2 Copper | Compare |
| ISO Cu-ETP | Compare |
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Frequently Asked Questions
What is the difference between ETP (C11000) and OFHC (C10200) copper?
ETP contains 0.02-0.04% oxygen for impurity control; OFHC has oxygen below 0.001%. OFHC is preferred for welding/brazing applications where hydrogen embrittlement is a concern and for vacuum/cryogenic service. ETP is more economical and sufficient for most electrical and general-purpose applications. The conductivity difference is negligible (~101% IACS for both).
References & International Standards
- ASTM International. Standard Specifications for Steel & Metal Alloys. astm.org
- International Organization for Standardization (ISO). Metallic Materials — Cross-Reference Database. iso.org
- American Iron and Steel Institute (AISI). Steel Grade Designations & Equivalents. steel.org
- European Committee for Standardization (CEN). EN Steel Standards & Numbering System. cencenelec.eu