CSA C22.2 No. 5-16 (2019) – Safety Standard for Molded-Case Circuit Breakers, Molded-Case Switches, and Circuit-Breaker Enclosures

Scope and Applicability

CSA C22.2 No. 5-16 (2019) is the third edition of the Canadian national standard for moulded-case circuit breakers, moulded-case switches, and circuit-breaker enclosures, originally published in 2016 and reaffirmed in 2019. The standard prescribes safety requirements for low-voltage power circuit protection devices intended for use in accordance with the Canadian Electrical Code, Part I (CE Code). These devices are designed to interrupt fault currents and provide overcurrent protection in residential, commercial, and industrial installations.

The scope covers circuit breakers rated up to 1000 V AC (50/60 Hz) and 1500 V DC, with continuous current ratings from 15 A up to 6300 A. Acceptable enclosures include general-purpose, weatherproof, dust-tight, and submersible types as classified in CSA C22.2 No. 94.1. The standard also applies to integrated trip units, both thermal‑magnetic and electronic, that are supplied as part of the circuit breaker assembly.

Devices covered by this standard are intended to be used in systems where the prospective symmetrical fault current does not exceed 200 kA RMS symmetrical, provided the circuit breaker is correctly selected for the available fault current at its point of installation.

Technical Requirements

The technical provisions in CSA C22.2 No. 5-16 (2019) are grouped into design, performance, and marking categories. The following subsections highlight the most critical requirements.

Voltage and Current Ratings

Each circuit breaker must be marked with its rated voltage (AC, DC, or both), continuous current rating at 40 °C ambient (unless otherwise specified), and the maximum interrupting capacity at the rated voltage. The standard permits rating at multiple voltages, but the interrupting capacity typically decreases as the voltage increases. For DC ratings, the time constant and the number of poles in series are specified.

Dielectric Voltage-Withstand

All live parts must be insulated from one another and from accessible metal parts to withstand the following test voltages for 60 seconds without breakdown or leakage current exceeding 20 mA:

For DC circuits, the test voltage is increased by 1.414 times the AC value, and the test duration is 60 s. Creepage and clearance distances are also specified in relation to pollution degree (PD2 or PD3) and material group.

Temperature Rise and Thermal Characteristics

Circuit breakers must carry 100 % of their rated current continuously without exceeding the maximum allowable temperature rise limits for connections, handle, and enclosure. Common limits include 65 °C for terminals, 35 °C for the operating handle, and 50 °C for accessible external surfaces, measured at an ambient of 40 °C. The standard also requires thermal-magnetic trip units to meet time‑current characteristics within ±20 % for overload conditions and a defined instantaneous trip current band.

Interrupting Capacity and Calibration

Interrupting capacity (IC) testing is performed at the rated voltage with a specified power factor (e.g., 0.45–0.50 for AC tests). The circuit breaker must clear the fault and reclose safely, with no fire hazard or electrical continuity failure. For IC tests exceeding 10 kA, a capacitor‑switching test may be required. Furthermore, trip units must be calibrated at 40 °C; the manufacturer must declare the calibration temperature and the effect of ambient temperature on trip performance.

Implementation Highlights

Applying CSA C22.2 No. 5-16 (2019) to product design and approval involves several practical considerations.

• Dual Certification with UL 489: Owing to the high alignment between the two standards, many manufacturers obtain a single set of tests that satisfy both UL 489 and CSA C22.2 No. 5-16 (2019). However, the Canadian standard requires additional tests, such as the 125 % continuous current rating test for certain frame sizes and a different marking order.
• Enclosures: All enclosures must be evaluated in accordance with CSA C22.2 No. 94.1 or the applicable enclosure standard. The internal barriers, wiring space, and accessibility of live parts are subject to specific dimensional gauges and tools.
• Marking: Every circuit breaker must display the CSA monogram or a recognized certification mark, the series number, rated voltage, interrupting rating, and the ambient temperature if different from 40 °C. The marking must be indelible and located on a visible surface.

Compliance Notes

Certification to CSA C22.2 No. 5-16 (2019) is a legal requirement in all Canadian provinces and territories under the authority of the CE Code and the provincial electrical safety acts. The following points are essential for compliance:

• Accredited Certification Body: The submittal must be made to a certification body accredited by the Standards Council of Canada (SCC), such as CSA Group, Underwriters Laboratories of Canada (ULC), or Intertek.
• Factory and Witness Testing: All testing must be performed in a lab accredited to ISO/IEC 17025, with witness testing by the certification body. Routine production tests, such as dielectric and calibration checks, must be documented.
• Periodic Audits: The certification body conducts regular follow-up inspections (quarterly or semi‑annually) to verify that production maintains compliance with the certified design.
• Variations: Any deviation from the certified construction or performance requires a new evaluation or a partial re‑qualification depending on the nature of the change.

Frequently Asked Questions

Article prepared for informational purposes. For full text, refer to CSA C22.2 No. 5-16 (2019) available from CSA Group. Compliance guidance should be verified with a qualified certification engineer.

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