CSA C22.2 No. 124-16: A Comprehensive Guide to Thermoplastic-Insulated Wires and Cables

Scope and Application of CSA C22.2 No. 124-16

CSA C22.2 No. 124-16, titled Thermoplastic-Insulated Wires and Cables, is a foundational safety standard within the Canadian Electrical Code (CE Code), Part II series (category C22.2). This standard applies to single-conductor and multi-conductor wires and cables insulated with a thermoplastic compound, typically polyvinyl chloride (PVC), with or without a nylon jacket. It outlines the construction, performance, testing, and marking requirements for wire types designated as T, TW, THW, THWN, and THHN, rated for 300 V or 600 V.

These wires are primarily intended for general-purpose building wiring in dry, damp, and wet locations as specified by the Canadian Electrical Code, Part I (CSA C22.1). The standard covers copper and aluminum conductors ranging from 18 AWG to 2000 kcmil. It is the direct Canadian counterpart to UL 83 in the United States, though it retains specific requirements tailored to the Canadian regulatory and environmental context.

Excluded from the scope are mineral-insulated cables (covered by C22.2 No. 52), high-temperature cables rated above 125°C, and specialty coaxial or communication cables. The standard focuses exclusively on general-purpose power and lighting circuit wiring widely used in residential, commercial, and industrial construction.

Core Technical Requirements and Construction

Conductor and Insulation Materials

The standard requires conductors to meet the specifications of CSA C22.2 No. 0.3 for specific testing and CSA C22.2 No. 0.10 for conductor material. Conductors are typically solid or stranded copper or aluminum. The insulation must be a thermoplastic PVC compound that meets specific physical and electrical properties after aging, heat shock, and cold bend conditioning tests.

A defining feature of many wires under this standard is the optional nylon jacket (for THHN/THWN types), which provides increased mechanical protection, chemical resistance, and facilitates easier pulling through conduits. The absence or presence of this jacket, combined with the temperature rating, differentiates the wire types.

Voltage Ratings and Temperature Classification

The temperature rating dictates the application environment and ampacity potential. Table 1 summarizes the primary classifications defined in the standard:

Table 1: Temperature and location ratings for thermoplastic