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CAN CSA C60888-03 Technical Guide: Zinc-Coated Steel Wires for Overhead Line Conductors
Understanding the Specifications, Testing, and Compliance Requirements for Galvanized Steel Wires Used in Stranded Overhead Conductors
Scope and Application
CAN/CSA C60888-03 is the Canadian adoption of the International Electrotechnical Commission standard IEC 60888:1987 (with amendments), titled Zinc-coated steel wires for stranded conductors. This standard specifies the requirements for zinc-coated (galvanized) round steel wires intended for use in the manufacture of stranded conductors for overhead power transmission and distribution lines. The standard is widely referenced by utilities, conductor manufacturers, and testing laboratories across Canada and in other jurisdictions that recognize CSA standards.
The standard applies to steel wires with nominal diameters ranging from 1.25 mm to 5.50 mm, drawn from high-quality carbon steel rod and continuously hot-dip galvanized after drawing. It defines two classes of zinc coating — Class A (regular) and Class B (heavy) — as well as two tensile strength grades: Standard Grade (SG) and Higher Strength (HS). The document is essential for ensuring mechanical reliability and corrosion resistance of the steel core or reinforcement in ACSR (Aluminum Conductor Steel Reinforced) and similar composite conductor designs.
Tip: CAN/CSA C60888-03 is technically identical to IEC 60888:1987 with minor Canadian deviations. Users working on cross-border projects should verify the specific edition referenced by local utilities.
Technical Requirements
Dimensional Tolerances
The standard mandates strict tolerances on wire diameter, out-of-roundness (ovality), and length of acceptable coating. The nominal diameter of the wire shall not deviate by more than ±1.5 % for diameters ≥ 2.00 mm and ±2.0 % for smaller diameters. Ovality, defined as the maximum difference between any two perpendicular diameter measurements along the same cross-section, shall not exceed 0.05 mm for diameters up to 3.00 mm and 0.08 mm for larger diameters.
Tensile and Elongation Requirements
Wires must meet or exceed the breaking load calculated from the nominal cross-sectional area and the specified minimum tensile strength. Standard Grade wire has a minimum tensile strength of 1240 MPa, while Higher Strength wire requires at least 1380 MPa. Elongation after fracture, measured on a 250 mm gauge length, shall be no less than 3.0 % for Standard Grade and 2.5 % for Higher Strength.
Zinc Coating Requirements
Two coating classes are defined based on the mass of zinc per unit area of wire surface. Class B coating provides approximately 50 % greater zinc mass than Class A, offering enhanced corrosion protection in marine or industrial environments. The minimum zinc mass varies with wire diameter as shown in Table 1.
| Nominal Diameter (mm) | Class A Min. Zn Mass (g/m²) | Class B Min. Zn Mass (g/m²) |
|---|---|---|
| 1.25 – 1.50 | 100 | 150 |
| 1.51 – 2.00 | 120 | 180 |
| 2.01 – 2.50 | 140 | 210 |
| 2.51 – 3.00 | 160 | 240 |
| 3.01 – 4.00 | 200 | 300 |
| 4.01 – 5.50 | 230 | 345 |
Table 1: Minimum zinc coating mass per unit area for Class A and Class B wires.
The coating must also pass the following qualification tests:
- Uniformity (Preece test): Wires are immersed in copper sulphate solution for a specified number of dips; no exposed steel (copper deposit) is allowed.
- Adhesion (wrapping test): The wire is wrapped around a mandrel of its own diameter; the coating shall not flake or peel.
- Continuity: The coating shall be free from bare spots, blisters, and other defects visible without magnification.
Mechanical Properties Summary
| Grade | Min. Tensile Strength (MPa) | Min. Elongation (%) on 250 mm | Min. Number of 180° Bends |
|---|---|---|---|
| Standard Grade (SG) | 1240 | 3.0 | 4 |
| Higher Strength (HS) | 1380 | 2.5 | 3 |
Table 2: Mechanical property requirements for zinc-coated steel wires per CAN/CSA C60888-03.
Important: The bend test is performed on a sample of wire that is bent through 180° around a mandrel having a diameter equal to the wire nominal diameter. The number of full bends required depends on the wire grade, as shown in Table 2.
Implementation Highlights
Manufacturing Process
The steel rod is first cleaned by pickling in acid to remove scale, then drawn through a series of dies to achieve the final diameter. Galvanizing is performed by passing the wire through a molten zinc bath (hot-dip process). The zinc bath temperature and immersion time are controlled to achieve the required coating mass and to ensure a uniform alloy layer between the zinc and steel substrate. After galvanizing, the wire may be wiped or air-knifed to control coating thickness.
Sampling and Lot Testing
For acceptance testing, the standard defines sampling plans based on lot size. A lot consists of coils from the same production run, of the same diameter, grade, and coating class. Tests for mechanical properties and zinc mass are performed on a representative number of samples. If any sample fails, double the number of samples are retested; failure of a retest results in rejection of the lot.
Marking and Packaging
Each coil must be securely bound and labeled with the manufacturer’s name or trademark, wire nominal diameter, grade (SG or HS), coating class (A or B), and the standard number. A tag or durable label is required, and the coil weight should be stated on the packing list.
Industry Practice: Many Canadian utilities specify Class B coating for coastal or highly polluted regions. Class A is often adequate for inland rural environments. Always consult the conductor specification to match coating class with expected service conditions.
Compliance and Certification Notes
Conformity to CAN/CSA C60888-03 is typically demonstrated through type tests and lot acceptance tests performed by the manufacturer or an accredited third-party laboratory. The standard does not mandate third-party certification, but procurement contracts often require that test results be attested by a professional engineer or a recognized certification body such as CSA Group.
It is important to note that CAN/CSA C60888-03 includes a national deviation from IEC 60888:1987: the Canadian edition requires that all wires subject to the standard also meet the additional elongation provisions specified in CSA C22.2 No. 0.4 (Bare and Covered Conductors). Specifically, the minimum elongation for Standard Grade wire is set at 3.0 % instead of the 2.5 % allowed by the IEC edition for certain diameters.
As of 2026, the standard has been reaffirmed by the Standards Council of Canada and remains in active use. Users are advised to verify the current approval status and any amendments that may have been issued since the original publication year.
Caution: Reaffirmed standards may not reflect the latest industry practices for corrosion protection or high-temperature conductor applications. For special requirements (e.g., ultra-high strength or corrosion-resistant coatings), consult the latest edition of CSA C60888 or an alternative standard such as ASTM A475 (zinc-coated steel wire strand).
Frequently Asked Questions
Q: What is the main difference between Class A and Class B zinc coating in CAN/CSA C60888-03?
A: Class B coating provides a heavier zinc mass (roughly 50 % more than Class A) for improved corrosion resistance. Class B is recommended for marine, coastal, or industrial environments where higher corrosion rates are expected. Both classes are equally strong mechanically; the difference lies solely in the amount of zinc applied.
A: Class B coating provides a heavier zinc mass (roughly 50 % more than Class A) for improved corrosion resistance. Class B is recommended for marine, coastal, or industrial environments where higher corrosion rates are expected. Both classes are equally strong mechanically; the difference lies solely in the amount of zinc applied.
Q: Is CAN/CSA C60888-03 identical to IEC 60888?
A: The Canadian edition is technically equivalent to IEC 60888:1987 with a few national modifications, the most notable being a higher minimum elongation requirement for Standard Grade wire (3.0 % in Canada vs. 2.5 % in the IEC edition for some diameter ranges). Users should always refer to the Canadian edition when supplying wires for Canadian projects.
A: The Canadian edition is technically equivalent to IEC 60888:1987 with a few national modifications, the most notable being a higher minimum elongation requirement for Standard Grade wire (3.0 % in Canada vs. 2.5 % in the IEC edition for some diameter ranges). Users should always refer to the Canadian edition when supplying wires for Canadian projects.
Q: Which testing method is used to determine zinc coating mass per unit area?
A: The gravimetric method is the primary referee method per the standard. A wire sample of known surface area is immersed in a solution that dissolves the zinc coating but not the steel base (e.g., inhibited hydrochloric acid). The mass loss before and after immersion gives the coating mass per unit area.
A: The gravimetric method is the primary referee method per the standard. A wire sample of known surface area is immersed in a solution that dissolves the zinc coating but not the steel base (e.g., inhibited hydrochloric acid). The mass loss before and after immersion gives the coating mass per unit area.
Technical Article — 2026 | Published under International Standards Documentation Guidelines