CSA C22.2 No. 38-18: Thermoplastic-Insulated Wires and Cables – Technical Overview and Compliance

CSA C22.2 No. 38-18 is the latest edition of a longstanding Canadian standard that specifies construction, performance, and testing requirements for thermoplastic-insulated wires and cables. Published by the Canadian Standards Association (CSA Group), this standard is essential for manufacturers, installers, and inspectors working with electrical wiring systems governed by the Canadian Electrical Code (CEC, CSA C22.1). It covers a broad range of single‑conductor and multiconductor cables that use thermoplastic insulation materials such as polyvinyl chloride (PVC) and nylon for applications up to 600 V (and limited types at 300 V or 1000 V). This technical article provides a detailed overview of the standard’s scope, critical technical requirements, implementation considerations, and compliance notes.

1. Scope and Application

1.1 Covered Products

CSA C22.2 No. 38-18 applies to thermoplastic-insulated wires and cables intended for installation in accordance with the CEC. The products covered include:

Single‑conductor building wires (e.g., T90, TW, THW, THWN) in sizes from 16 AWG to 1000 kcmil.
Multiconductor cables (e.g., T90 Nylon, MTW) for power, lighting, and control circuits.
Wires rated for dry, damp, or wet locations with conductor temperature ratings of 60 °C, 75 °C, 90 °C, and 105 °C.
Copper or aluminum conductors – solid or stranded.

Tip: Always verify the temperature rating and location type (dry/wet) when selecting a cable type. For example, TW is suitable for wet locations at 60 °C, while T90 is for dry locations at 90 °C.

1.2 Exclusions

The standard explicitly excludes cables with other insulation types (e.g., thermoset, cross‑linked polyethylene) and products such as flexible cords, fixture wires, and specialty cables covered by other CSA standards (e.g., CSA C22.2 No. 49 for flexible cords).

2. Technical Requirements

2.1 Construction

The standard specifies detailed construction parameters:

Conductors: Copper or aluminum, solid or stranded, meeting material and resistivity requirements of ASTM B3, B8, or B787.
Insulation: Thermoplastic compounds (PVC, nylon, or blends) must have uniform thickness, with minimum thicknesses tabulated for each AWG size and voltage rating.
Jackets: For multiconductor cables, an overall jacket of PVC or other thermoplastic material is required, with thickness and material properties specified.
Separation: Conductors in multiconductor cables must be separated by fillers or jackets to maintain physical and electrical integrity.

2.2 Performance and Testing

All products must pass a suite of mandatory tests:

Test	Standard / Method Reference	Requirement
Dielectric Withstand (Hi‑Pot)	CSA C22.2 No. 0.4 or IEEE 400.2	No breakdown at 1.5 kV for 1 min (600 V rated cables)
Insulation Resistance	CSA C22.2 No. 0.3 (or UL 1581)	≥ 2 MΩ·km at 20 °C
Flame Test (FT1/FT2/FT4)	CSA C22.2 No. 2556	Horizontal or vertical flame propagation limits
Heat Shock (at elevated temp)	CSA C22.2 No. 38 Annex A	No cracks or deformation after 1 h at specified temp
Cold Bend (at −25 °C)	CSA C22.2 No. 38 Sec. 5.9	No cracking after wrapping around mandrel
Oil Resistance (if required)	CSA C22.2 No. 38 Annex B	Maximum swelling and no cracking after immersion

Did you know? CSA C22.2 No. 38-18 now harmonizes many test methods with the UL 83 standard, easing certification for products sold in both Canada and the U.S.

2.3 Marking and Identification

Each product must be permanently marked with:

Manufacturer’s name or trademark.
CSA certification mark and file number.
Cable type designation (e.g., T90, THWN).
Conductor size (AWG or kcmil).
Voltage rating (e.g., 600 V).
Temperature rating (if not evident from type).
“FT4” or other flame‑test rating where applicable.

3. Implementation Guidelines

3.1 Manufacturing Considerations

Producers must establish a quality control program that includes incoming material verification, in‑process checks of insulation thickness and concentricity, and routine batch testing for electrical and physical properties. A recognised third‑party certification body (e.g., CSA Group) conducts initial type testing and periodic factory inspections to maintain listing.

Attention: Changes in thermoplastic compound formulation or conductor supplier can affect certification. Always submit a re-assessment to the certification body before changing any critical component.

3.2 Installation Best Practices

When using cables listed to CSA C22.2 No. 38-18, installers should:

Respect the maximum conductor temperature for the circuit design (ambient + rise).
Avoid pulling cables where insulation may be abraded (use appropriate lubricants).
Ensure that connectors and terminations are rated for the cable’s temperature class.
For wet‑location types (e.g., TW, THWN), verify that the cable is suitable for continuous immersion.

Critical: Exceeding the conductor’s temperature rating can cause insulation failure, short circuits, and fire. Use de‑rating tables in the CEC when ambient temperatures exceed 30 °C.

3.3 Compatibility with Connectors and Panels

Cable types with nylon jackets (e.g., THHN/THWN) have a harder outer surface, which may require connectors with a larger clamping range. Always check manufacturer compatibility tables.

4. Compliance and Certification Notes

4.1 Regulatory Recognition

CSA C22.2 No. 38-18 is adopted by reference in the Canadian Electrical Code (CEC, CSA C22.1) and is mandatory for wiring materials used in electrical installations in Canada. Provincial authorities may also require product certification to this standard as a condition of adoption.

4.2 Third‑Party Certification Process

Application: Manufacturer submits product specifications and construction details.
Testing: Samples are tested at an accredited laboratory per the standard’s test matrix.
Factory Inspection: Certification body audits the production line and quality system.
Listing: Upon successful completion, the product is included in the certification body’s listing directory and may bear the CSA mark.
Surveillance: Annual or biennial unannounced inspections and sample testing continue for the duration of the certificate.

Tip: The CSA mark alone is not sufficient; the product label must also show the specific standard number (C22.2 No. 38) to be accepted by local inspectors.

4.3 Common Non‑Conformities

Typical issues found during certification include insufficient insulation thickness, poor adhesion of nylon jacket, and failure of the dielectric test at the specified voltage. Batch‑to‑batch consistency of thermoplastic compounds is also a frequent challenge.

Frequently Asked Questions

Q: Is CSA C22.2 No. 38-18 harmonized with any U.S. standard?
A: Yes, it is largely harmonized with UL 83 (Thermoplastic-Insulated Wires and Cables) and NEMA WC 70. Many products carrying both CSA and UL marks are accepted in both jurisdictions.

Q: What are the main differences between T90 and THHN types?
A: T90 is a dry‑location cable rated for 90 °C; THHN is also 90 °C dry but includes a nylon jacket and is also rated for 75 °C wet (THWN). THHN is more versatile for mixed environments.

Q: Can aluminum conductors be used with all types covered by this standard?
A: Yes, the standard includes both copper and aluminum. However, aluminum conductors require proper connector compounds and anti‑oxidation treatments as per the CEC.

Q: Does the standard cover cables rated above 600 V?
A: Some types are rated at 1000 V (e.g., R90, RW90). These are also covered by CSA C22.2 No. 38, but always check the product marking for the actual voltage rating.

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