1. What is THHN wire? What is CSA certification?
1.1 THHN wire
THHN stands for "Thermoplastic High Heat-resistant Nylon-coated," referring to high-heat-resistant thermoplastic wire with PVC insulation and a nylon jacket. Its main features include:
Used in dry or slightly humid environments
Temperature rating up to 90°C (dry) and 75°C (humid)
PVC insulation and nylon jacketing resist abrasion, oil, and gas.
The standard voltage rating is 600V, making it widely used in building wiring.
1.2 CSA Certification
CSA, the abbreviation for the Canadian Standards Association, is responsible for developing and enforcing safety performance standards for electrical products and issuing certification marks, including the CSA mark and related product standards (such as CSA C22.2).
CSA certification uses a rigorous testing system to ensure that products comply with Canadian electrical safety regulations and performance requirements.
The CSA mark is widely recognized by Canadian electrical inspectors and related agencies and is highly respected.
2. THHN and CSA: Standards and Compatibility
1. CSA C22.2 No. 75 Standard
To obtain CSA certification, THHN cable must comply with CSA C22.2 No. 75, the Canadian equivalent of US UL 83.
Manufacturers can obtain CSA-approved THHN cable certification under this standard.
Specifics:
Certain THHN/THWN-2 cable products are labeled as meeting both UL 83 and CSA C22.2 No. 75 standards, meaning they are "dual-rated."
This certification covers multiple performance indicators, including temperature, moisture resistance, and mechanical strength.
2. THHN cable (T90 cable) Designation in Canada
In the Canadian market, THHN is commonly referred to as T90 nylon cable. It is a high-temperature-resistant thermoplastic cable with a nylon jacket.
Several Canadian electricians pointed out, "We don't call it THHN, we call it T90" (the Canadian standard for THHN).
This difference in terminology reflects the usage practices of different markets, but the underlying product performance is the same.
3. The Significance and Difference of cable THHN/THWN‑2 Dual Certification
1. THHN vs. THWN‑2 Difference
THHN cable: UL83 standard, CSA C22.2 No. 75 optional certification.
Temperature: 90°C dry, 75°C wet.
For use in dry or temporarily humid environments.
THWN-2 cable: An upgraded version for humid environments, with standards closely aligned with CSA.
Temperature: Up to 90°C dry and wet.
Suitable for humid or harsh environments, such as underground pipelines, chemical plants, and coastal areas.
Most modern THHN cables are actually THWN‑2 capable and are therefore considered dual-certified, dual-specification compatible products (UL + CSA).
2. Why choose dual certification or THWN‑2 cable?
1.CSA certification ensures product compliance and legality in Canada, while also facilitating use in cross-border projects across North America.
2.THWN‑2 offers advantages in humid environments, consistent temperature ratings, and enhanced safety.
Versatile, it reduces inventory requirements and facilitates unified selection.
4. Alignment of the Certification Process with the Standards System
1. CSA Certification Process (Taking Electrical Wiring Products as an Example)
Application Testing: Products are submitted to CSA laboratories for material, electrical, temperature resistance, mechanical, and fire performance testing.
Verification Standards: Compliance is performed against the Canadian Electrical Code (CEC) and the CSA C22.2 series of standards.
After obtaining certification, products can be marked with the CSA mark and may be included as equipment recognized under local regulations.
2. Canadian Electrical Code (CEC)
The CEC is a binding electrical installation specification published by CSA. The 26th edition was released in March 2024.
The CEC is structured as follows: Part I (Installation Safety Standard), Part II (Product Evaluation Standard), and Part IV (Goal-Oriented Specification for Industrial Users).
The CEC requires all permanent wiring products to comply with Part II standards (such as CSA C22.2 No. 75).
5. Practical Selection Recommendations and Considerations
1.When using THHN wire in Canadian projects, please confirm that the product is certified to CSA C22.2 No. 75 or marked as CSA-approved.
2.For wet locations, THWN-2 (dual-certified by CSA and UL for wet conditions) is preferred.
3.If you encounter the "THHN" designation without the CSA mark when purchasing, ask the manufacturer for certification details or select a certified product instead.
4.Note terminology differences: Canada calls it T-90, and while this term is also used outside of the code, its correspondence with THHN should be understood.
5.For projects involving cross-border or international projects, it is recommended to select dual-certified (UL and CSA) models to simplify inventory and regulatory compliance.